RE Wall Design Manual

8/12/2019 RE Wall Design Manual

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DESIGN MANUAL

ForReinforced Earth ® Walls

The Reinforced Earth Com an!"#$% West&ood Center Dri'e( S)ite $$**( +ienna( +A

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5,*** The Reinforced Earth Com an!6 This man)al is the ro ert! of The Reinforced Earth Com an!6An! re rod)ction or distri7)tion &itho)t the e3 ress &ritten consent of RECo is rohi7ited6



TA8LE 4F C4NTENTS

DESIGN MANUAL

$6* INTR4DUCTI4N,6* STANDARD REFERENCES.6* TERMIN4L4G9%6* GENERAL DESIGN

%6$ Descri tion of a Reinforced Earth Wall%6, Desi:n Information Needs%6. Loadin: Conditions

16* MATERIALS16$ 8ac;fill16, Reinforcin: Steel16. Facin:s

16% Connections161 8earin: /ads16# Filter Cloth

#6* STA8ILIT9#6$ E3ternal Sta7ilit!#6$6$ Slidin: and 4'ert)rnin:#6, Internal Sta7ilit!#6. 4'erall <Glo7al= Sta7ilit!

06* F4UNDATI4N C4NSIDERATI4NS06$ 8earin: Ca acit! of the Fo)ndation Soil06, Tr)e A7)tment 8earin: Ca acit!

06. Total Settlement06% Differential Settlement061 Fo)ndation Sta7ili>ation Methods

REFERENCES"6* WALL C4NSTRUCTI4N DRAWINGS AND GENERAL DETAILS

"6$ General Notes"6, Ele'ation"6. T! ical Sections"6% T! ical /anel and Connection Details"61 Reinforcin: Stri s"6# Le'elin: /ad Ste s

?6* T9/ICAL DESIGN DETAILS?6$ Sli @oints?6, 8)tt @oints?6. Corner Elements?6% Co in:?61 Slo e-to /anels?6# Connections?60 Traffic 8arriers




?6" /ara ets ?6? 8rid:e Seats?6$* ori>ontal Incl)sions <Draina:e Str)ct)res( /i elines( etc6=?6$$ +ertical Incl)sions?6$. Ac)te Corners

?6$% C)r'es?6$1 Tiered Walls




1.0 INTRODUCTION

Welcome

Welcome to the Desi:n Man)al for Reinforced Earth®

Walls6 This man)al &ill e3 lain&hat a Reinforced Earth &all is and ho& it &or;s( as &ell as o)tline the man! &a!s !o)r

roBects can 7enefit from this technolo:!6 The Man)al also defines and disc)sses theinformation needed for the desi:n of a Reinforced Earth retainin: &all6 It incl)des ane3tensi'e :lossar! and n)mero)s references to enhance !o)r ;no&led:e of this e3citin:and 'ersatile earth retention s!stem6

What Are Reinforced Earth Walls?

Reinforced Earth retainin: &alls are an economical &a! to meet e'er!-da! earth retention

needs for hi:h&a! and 7rid:e :rade se arations( railroads and mass transit s!stems(&aterfronts( air orts( loadin: doc;s( ind)strial facilities and commercial and residentialde'elo ments6 The! are also )sed in res onse to diffic)lt desi:n conditions s)ch as 'er!hi:h str)ct)res( restricted s ace( )nsta7le slo es and oor fo)ndation conditions6 Theinherent stren:th and fle3i7ilit! of the o'erall &all s!stem :i'es desi:ners a o&erf)l&a! to economicall! sol'e diffic)lt sta7ilit! iss)es for str)ct)res s)7Bect to floodin: orother h!drod!namic forces( or those in seismicall! acti'e areas6

How Do I Obtain a Reinforced Earth Design?

The Reinforced Earth Com an! <RECo= ioneered this technolo:! and de'elo ed it o'erthe last .* !ears to a meet a &ide 'ariet! of roBect re )irements6 Since s ecific roBectinformation is al&a!s re )ired to arri'e at a safe and economical sol)tion( a l!in:Reinforced Earth technolo:! is a collaborative effort in'ol'in: the 4&ner and2or the4&ner s Cons)ltant and The Reinforced Earth Com an! <RECo=6 This Man)al is &rittennot onl! to hel !o) )nderstand Reinforced Earth technolo:! and terminolo:!( 7)t also toidentif! the information that RECo needs from !o) in order to com lete a desi:n6

There is nothin: m!sterio)s a7o)t desi:nin: a Reinforced Earth &all( 7)t the 7est andmost economical desi:ns are al&a!s the res)lt of e3 erience and B)d:ment6 That is &h!RECo ro'ides com lete Reinforced Earth &all desi:ns( ena7lin: !o) to 7enefit from o)r

e3 erience6 Since &e do the desi:n( this Man)al is not intended to train !o) to desi:nReinforced Earth &alls6 Instead( it &ill hel !o) identif! sit)ations on !o)r roBect &herea Reinforced Earth &all is technicall! a ro riate and hel !o) )nderstand the &alldra&in:s !o) recei'e from )s6 It &ill also allo& !o) to do a reliminar! si>in: of thestr)ct)re and ena7le !o) to )nderstand and estimate not onl! the loads that a ReinforcedEarth str)ct)re can carr!( 7)t also the loads the Reinforced Earth str)ct)re &ill a l! tothe site &here it is 7)ilt6

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Organization and Numbering S stem of this !anual

This man)al has nine sections incl)din: this Introd)ction6 The other sections areStandard References( Terminolo:!( General Desi:n( Materials( Sta7ilit!( Fo)ndationConsiderations( Wall Constr)ction Dra&in:s and T! ical Desi:n Details6 The sections

are n)m7ered $ thro):h ?( &ith s)7sections desi:nated 7! decimal oints( i.e6( Section16,( &ith fi:)res at the end of each section for eas! reference6 Follo&in: this format( thefi:)res for Section 16, are n)m7ered Fi:)re 16,6$( Fi:)re 16,6,( etc6 If a section has athree-di:it desi:nation( as does Section #6,6.( then the matchin: fi:)re n)m7er has fo)rdi:its( i.e6( Fi:)re #6,6.6$6 The last di:it of the fi:)re n)m7er is al&a!s that fi:)re sse )ence n)m7er &ithin the section6

Altho):h &e ho e !o) &ill read this man)al com letel!( &e )nderstand !o) ma! referonl! to a artic)lar section to ans&er a )estion a7o)t a roBect6 Therefore( &e ha'e triedto ma;e each section of te3t as nearl! self-contained as ossi7le so !o) can easil! :et theinformation !o) need6 Ine'ita7l!( this leads to some re etition that !o) ma! enco)nter if

!o) read se'eral sections or cha ters at once6 /lease let this re etition s)::est theim ortance of the information and )se the re etition to hel !o) 7etter )nderstand theinformation resented6

A Note about Dimensions

This man)al )ses Metric dimensions( &ith the En:lish <Im erial= con'ersion follo&in: in arentheses6 This con'ention is )sed in 7oth the te3t and the fi:)res6 Altho):h in mostcases the Metric dimension is more recise than the con'erted Im erial dimension( thedimensions )sed are for ill)strati'e )r oses onl! and ma! 'ar! sli:htl! from recisedesi:n or fa7rication dimensions d)e either to con'ersion or to sim lification a ro riateto the :)ideline character of this man)al6 Therefore( &hen re )ired for desi:n( recisedimensions sho)ld al&a!s 7e o7tained from contract lans or directl! from TheReinforced Earth Com an!6 RECo reser'es the ri:ht to chan:e the dimensions offa7ricated materials as needed6

"our #eedbac$ is Welcome

This doc)ment is intended to 7e )ser friendl!( and &e &elcome !o)r feed7ac; a7o)tim ro'ements that &ill ma;e it e'en more so6 We e3 ect to iss)e additions and re'isions

to this man)al as o)r technolo:! ad'ances( as &ell as in res onse to !o)r feed7ac;6Whether !o) )se it as a )ic; reference or as a fre )ent :)ide( &e ho e this Desi:nMan)al for Reinforced Earth Walls hel s !o) reach !o)r desi:n :oals on e'er! roBect6

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2.0 STANDARD REFERENCES

Reference is made thro):ho)t this man)al to the follo&in: re orts( s ecifications(te3t7oo;s and Reinforced Earth Com an! technical 7)lletins <detailed references to

section or a:e n)m7ers are :i'en in the te3t=

Constr)ction and )alit! Control Man)al for Reinforced Earth Str)ct)res( TheReinforced Earth Com an!( $??#( Section D - 8ac;fillin:6

D)ra7ilit!2Corrosion of Soil Reinforcement Str)ct)res( Federal i:h&a! AdministrationRe ort F WA-RD-"?-$"#( $??*6

In Sit) Soil Im ro'ement Techni )es( AAS T4-AGC-ART8A @oint Committee(S)7committee on Ne& i:h&a! Materials( Tas; Force ,0 Re ort( $??*6

Soil Mechanics and En:ineerin: /ractice( Second Edition( Harl Ter>a:hi and Ral h 86/ec;( @ohn Wile! Sons( $?#06

Standard S ecifications for i:h&a! 8rid:es( AAS T4J( $??# <Si3teenth Edition=($??" Interim( Di'ision I - Desi:n( Section 16.6

Standard S ecifications for i:h&a! 8rid:es( AAS T4( $??# <Si3teenth Edition=( $??"Interim( Di'ision I - Desi:n( Section 16"6

Standard S ecifications for i:h&a! 8rid:es( AAS T4( $??# <Si3teenth Edition=( $??"Interim( Di'ision I K Desi:n( Section $*6.,6

Standard S ecifications for i:h&a! 8rid:es( AAS T4( $??# <Si3teenth Edition=( $??"Interim( Di'ision II - Constr)ction( Section 06.6#6.6

S)7s)rface In'esti:ation and Im ro'ements for MSE Str)ct)res Constr)cted on /oorFo)ndation Soils( The Reinforced Earth Com an!( )ndated6

Technical 8)lletin MSE-$( Ser'ice Life( Allo&a7le Reinforcement Stress and Metal LossRates to 7e Used in the Desi:n of /ermanent MSE Str)ct)res( The Reinforced EarthCom an!( $??,( re'ised $??16

Technical 8)lletin MSE-#( A arent Coefficient of Friction( fJ( to 7e Used in the Desi:nof Reinforced Earth Str)ct)res( The Reinforced Earth Com an!( $??1

Technical 8)lletin MSE-0( Minim)m Em7edment Re )irements for MSE Str)ct)res(The Reinforced Earth Com an!( $??16

J American Association of State i:h&a! and Trans ortation 4fficials

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3.0 TERMINOLOGY

The follo&in: terms are defined for )se in this man)al

- S!m7ol for friction an:le6

- S!m7ol for )nit &ei:ht or densit!6

AASHTO K American Association of State i:h&a! and Trans ortation 4fficials6

Acceleratio Coe!!icie t K Coefficient 7ased on seismic acti'it! for a s ecific location6

Acti"e Eart# $re%%&re Coe!!icie t' ( a K Coefficient 7ased on the increase of hori>ontal ress)re( as determined 7! the form)la tan 2 (45 - φ / 2) 6

Acti"e )o e K The re:ion 7ehind the facin: of a Reinforced Earth &all in &hich theshear stress alon: the reinforcin: stri s is directed to&ard the facin:6 In cross section( the&idth of the acti'e >one 'aries from >ero at the toe of the str)ct)re to .* of thestr)ct)re hei:ht from mid-hei:ht of the &all to the to of the &all6

Ac&te Cor er K A corner formed 7! t&o se:ments of a Reinforced Earth &all that meetand form an an:le less than or e )al to ?* o( as meas)red from the fill side of the &all6

Allo*a+le ,eari - $re%%&re - Ultimate 7earin: ca acit! of fo)ndation soil red)ced 7!a l!in: a factor of safet!6

Allo*a+le Te %ile Stre -t# K The ortion of a material s )ltimate tensile stren:th thatma! 7e )sed for desi:n6 Allo&a7le tensile stren:th is determined from the !ield <or)ltimate= stren:th( red)ced 7! a s ecified factor of safet! and 7! a red)ction in crosssectional area to acco)nt for ser'ice life losses6

A K S!m7ol for tri7)tar! &all area6

A lie/ ,eari - $re%%&re K /ress)re a lied to fo)ndation soil 7! the str)ct)re 7ein:s) orted6

A% K S!m7ol for cross-sectional area of steel6

ASTM American Societ! for Testin: and Materials6

At Re%t Eart# $re%%&re Coe!!icie t' ( o - Coefficient 7ased on the hori>ontal ress)resneeded to remain at rest( as determined 7! the form)la 1-sin φ 6

, K S!m7ol for 7earin: &idth <at 7ase of &all( meas)red on the &all cross section=6

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,ac !ill K Soil fill laced 7ehind a str)ct)re or re laced in an e3ca'ation6

,i%#o % Mo/i!ie/ Met#o/ o! Slice% K 4ne of the common methods )sed to determine:lo7al sta7ilit!6

,lac %teel K 8are steel &itho)t :al'ani>ation or other coatin:6

,o&%%i e%4 $re%%&re Di%tri+&tio K Method of distri7)tin: fo)ndation load thro):h asoil mass 7ased on the si>e and sha e of the fo)ndation6

,ri/-e Seat K Reinforced concrete ca that s) orts 7rid:e 7eams and transfers loads tofo)ndation soils or dee fo)ndation elements6

,ro e ,ac Slo e K Slo e clim7in: from the to of a &all and le'elin: o)t at adistance from the front face no :reater than t&ice the hei:ht of the &all6

,eari - Ca acit5 6Ter7a-#i8 K Method of determinin: )ltimate 7earin: ca acit! offo)ndation soil6

,&tt 9oi t - +ertical 7rea; in a &all face &here &all ma! chan:e direction <&all anelsare not connected across the Boint=6

Ca%t I $lace 6CI$8 Co crete K Concrete o)red on-site in the location of intended )se6

C#ee *all K Clos)re &all at the end of a 7rid:e a7)tment6

Cl K Chemical s!m7ol for chlorides6

Coe!!icie t o! Sli/i - 6%oil to %oil8 - Frictional resistance of soil determined 7! the termtan φ ( &here φ is the friction an:le of the soil6

Co#e%io K Stren:th characteristic of soils determined 7! the interce t of the shearstren:th at >ero normal stress on the Mohr Co)lom7 en'elo <see also Frictio A -le =6

Co#e%io le%% Soil% K Soils e3hi7itin: stren:th rimaril! thro):h friction 7et&een soil articles :ran)lar soils6

Co#e%i"e Soil% K Soils e3hi7itin: stren:th rimaril! thro):h cohesion fine-:rained soils6

Co %oli/atio Settle:e t K Settlement occ)rrin: o'er time as 'oid s ace 7et&een soil articles in the soil mass decreases6

Co i - K /recast or cast-in- lace )nits )sed as to treatments for &alls6

Cor er Ele:e t K S eciali>ed recast facin: )nits that chan:e &all ali:nment at a artic)lar oint6

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Corro%io K /rocess of o3idation in metallic reinforcin: stri s that leads to loss ofthic;ness6

Co&lo:+ Met#o/ K More detailed earth ress)re theor! than Ran;ine Method 7ased ondensit! of retained soil( friction an:le of retained soil( hei:ht of &all( friction 7et&een

soil and &all( and an:les of re ose of &all and retained slo e6

Critical Str&ct&re K A str)ct)re &ith a desi:n life of $** !ears( s)ch as a 7rid:ea7)tment or a str)ct)re s) ortin: a railroad a str)ct)re that erforms a critical f)nction&here fail)re &o)ld ha'e )nacce ta7le conse )ences a str)ct)re that has 7eendesi:nated critical 7! the o&ner6

Cr&ci!or: $a el K Cross-sha ed recast anels )sed as one t! e of facin: forReinforced Earth &alls6

De %it5 o! Rei !orci - Stri % K N)m7er of reinforcin: stri s &ithin a :i'en &all face

area <:enerall! an area of ,6,1 sm ,%6, sfO=6

Di!!ere tial Settle:e t - Settlement difference 7et&een t&o oints located a ;no&ndistance a art6

Direct S#ear Te%t K La7orator! test to determine the ,-dimensional shear stren:th of asoil at a artic)lar normal load( there7! also determinin: the friction an:le and cohesion6

D& oi% Coati - K Thermal s ra!ed allo! coatin: com osed of "1 >inc and $1al)min)m6

Ecce tricit5 K 4ffset from the center of mass of the res)ltant force d)e to e3ternalloadin:6

E!!ecti"e Le -t# K The len:th of earth reinforcement that is o)tside the acti'e >one andinto the resisti'e >one6

E:+e/:e t K De th from :ro)nd s)rface to the to of the le'elin: ad of a ReinforcedEarth &all6

E$DM R&++er K Elastomer )sed to man)fact)re 7earin: ads for )se 7et&een anels ofa Reinforced Earth &all6

E;ter al Sta+ilit5 K Sta7ilit! conditions that are e3ternal to the reinforced 'ol)me andaffect the str)ct)re incl)des o'ert)rnin: and slidin:6

!< K PA arent coefficient of frictionP Frictional interaction 7et&een soil t! e andreinforcement in Reinforced Earth &all6

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Factor o! Sa!et5 K In :lo7al sta7ilit! a lications( the s)m of the resistin: forces di'ided 7! the s)m of the dri'in: forces6 In an! sit)ation( the amo)nt 7! &hich resistin: forcese3ceed dri'in: forces( e3 ressed as a ratio in decimal n)m7er format6

Filter Clot# K Geos!nthetic fa7ric )sed to co'er the 7ac;side of the anel Boints of

Reinforced Earth &alls to contain 7ac;fill &hile allo&in: draina:e6

Fi e% K Soil articles assin: a US Standard No6 ,** sie'e <01 µm=6

Fi i%#e/ Gra/e K Final ele'ation of :ro)nd s)rface for a :i'en location of constr)ction6

Fi ite Ele:e t 6Met#o/8 K T&o or three-dimensional modelin: method that e'al)atessoil2str)ct)re interaction 7! di'idin: the soil and2or str)ct)re into discrete elements andidentif!in: and anal!>in: h!sical characteristics of these elements6

Frictio A -le K An:le determined 7! an en'elo e lottin: shear stren:th 'ers)s normal

stress in la7orator! testin:( as determined 7! Mohr-Co)lom7 theor!6

Fro%t Hea"e K E3 ansion of soil d)e to free>in:6

F 5 K S!m7ol for !ield stren:th of steel6

Geo%5 t#etic K The :eneric term for all s!nthetic materials )sed in :eotechnicalen:ineerin: a lications( incl)din: :eote3tiles( :eo:rids( :eonets( :eomem7ranes and:eocom osites6

Geotec# ical 6E -i eeri -8 K Ci'il en:ineerin: disci line de'oted to e'al)ation of

ro erties of soil and roc; and to their interaction &ith en:ineered str)ct)res6

Glo+al Sta+ilit5 K Mass sta7ilit! of entire em7an;ment and fo)ndation e3ternal toReinforced Earth str)ct)re6

Gra"it5 Retai i - Str&ct&re K A retainin: str)ct)re that transfers :ra'itational anda lied loads directl! into the soil or roc; fo)ndation( &itho)t the )se of iles or otherdee fo)ndation elements6

Gra &lar ,ac !ill K 8ac;fill meetin: the h!sico-chemical re )irements s ecified forReinforced Earth &all a lications <also referred to as PSelect 8ac;fillP=6

G&tter Li e - 8ase ele'ation of :)tter located at to of &all6

H K S!m7ol for &all hei:ht <meas)red from to of le'elin: ad to to of &all anels=6

H= K S!m7ol for hei:ht from to of le'elin: ad to to of 7ro;en 7ac; slo e s)rchar:e6

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# K For &alls &ith slo in: fill on to of &all( s!m7ol for hei:ht meas)red to oint &heres)rface of slo in: fill intersects 'ertical line risin: from 7ac; end of reinforcin: stri s6

HA - s!m7ol for P i:h Adherence(P descri7in: the s)rface characteristics of ri77ed orladder reinforcin: stri s6

HA La//er A hi:h adherence < A= reinforcin: element )sed to add tensile stren:th tothe soil in a Reinforced Earth &all6 The A ladder is 1* mm &ide and formed from W$*&ires6

Hair i Co ectio K T! e of connection )sed &ith A stri s or A ladders in &ire-faced &all constr)ction6

Ha /le+ar Co ectio K T! e of connection )sed &ith ladder reinforcements in &ire-faced &all constr)ction6

Hori7o tal I cl&%io K Str)ct)re that e3tends hori>ontall! thro):h <Reinforced Earth= 7ac;fill s)ch as a i eline or a draina:e str)ct)re6

H5/ro%tatic $re%%&re K /ress)re res)ltin: from &ater6 Differential h!drostatic ress)reres)lts from different &ater le'el hei:hts in front of( inside or 7ehind a str)ct)re6

I::e/iate Settle:e t K Settlement of a str)ct)re that coincides in time &ith itsconstr)ction6

I cl&%io 6Hori7o tal8 K See ori>ontal Incl)sion6

I cl&%io 6>ertical8 K See +ertical Incl)sion6

I e;te %i+le K Term a lied to materials s)ch as steel reinforcin: stri s that deformm)ch less readil! than does the 7ac;fill in &hich the! are em7edded6

I ter al Sta+ilit5 K Sta7ilit! conditions affectin: the Reinforced Earth 'ol)me(incl)din: reinforcement )llo)t and tensile resistance6

( a ' Acti"e Eart# $re%%&re Coe!!icie t K Coefficient 7ased on the increase of hori>ontal ress)re( as determined 7! the form)la tan 2 (45 - φ / 2) 6

( o' At Re%t Eart# $re%%&re Coe!!icie t - Coefficient 7ased on the hori>ontal ress)resneeded to remain at rest( as determined 7! the form)la 1-sin φ 6

L K S!m7ol for len:th6

La//er Rei !orce:e t% K Earth reinforcements consistin: of t&o lon:it)dinal &ires&ith cross-&ires at re:)lar inter'als6 T&o t! es are )sed in Reinforced Earth &alls K ALadders and Wide Ladders <see indi'id)al definitions=6

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Lar-e Recta -&lar $a el% K /anels meas)rin: $61 meters hi:h 7! . meters &ide onet! e of facin: for Reinforced Earth &alls6

Le"eli - $a/ K Lean concrete ad )sed as a smooth &or;in: s)rface on &hich to set thefirst le'el of recast anels &hen constr)ctin: a Reinforced Earth &all6

Li"e Loa/ K Load a lied to a str)ct)re( &here the load does not remain stationar! andma! 'ar! in ma:nit)de6

Ma- e%i&: %&l!ate %o& / e%% K La7orator! test )sed to determine d)ra7ilit! of soil6

Mar-i al Soil% K Soils that ma! not readil! s) ort the loads a lied 7! certainstr)ct)res6

MSE K Mechanicall! Sta7ili>ed Earth6

N K N)m7er of reinforcements in a :i'en tri7)tar! area of a Reinforced Earth &all6

Nor:al $ool?Floo/ Le"el K Statisticall! deri'ed standard <normal= &ater le'el andele'ated <flood= &ater le'el for a s ecific location6

O e Gra/e/ A--re-ate K Cr)shed stone or :ra'el &ith a lo& ercenta:e of sand( siltor cla! <)s)all! less than $* 7! &ei:ht=6

O"ert&r i - K 4)t&ard rotation of the to of a :ra'it! str)ct)re6

$ S!m7ol for )llo)t ca acit! of reinforcements6

$ara et /recast or cast-in- lace concrete 7arrier or rail located on to of a ReinforcedEarth &all6

$article %i7e K The diameter of a soil article in 7ac;fill6

$C 6$oi t o! C&r"at&re8 K Geometric startin: oint of a c)r'e6

H - Scale )sed to indicate the acidit! <ran:e * to 0= or al;alinit! <ran:e 0 to $%= of soil6

$#5%ico c#e:ical Re4&ire:e t% K Re )irements for the h!sical( chemical andcond)cti'e characteristics of soil 7ac;fill )sed in Reinforced Earth &all a lications6

$la%ticit5 I /e; K Soil arameter determined in a la7orator! 7! the Atter7er: testtechni )e sho&in: the difference in &ater content for a soil in its li )id limit statecom ared to the same soil in its lastic limit state6

$ore @ater K Water occ) !in: the 'oid s ace 7et&een articles in a soil mass6

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$reca%t Co crete K Concrete cast at a lant in standard sha es( s)ch as anels andco in:( for shi ment and installation at roBect sites6

$T 6$oi t o! Ta -e c58 K Geometric end oint of a c)r'e6

$>C K /ol!'in!l chloride6

Ra/i&% o! C&r"at&re K Geometric distance from center of radi)s to associated c)r'e6

Ra /o: ,ac !ill 8ac;fill located o)tside the reinforced 'ol)me of a Reinforced Earth&all6

Ra i e Met#o/ K Sim lified earth ress)re theor! 7ased on the densit! of the retainedsoil( the hei:ht of the &all and the friction an:le of the retained soil6

RECo K The Reinforced Earth Com an!6

Rei !orce/ Eart# ® @all K Mechanicall! Sta7ili>ed Earth &all s!stem consistin: of recast concrete facin: anels( metallic reinforcin: stri s and :ran)lar 7ac;fill6

Rei !orci - ,ar 6Re+ar8 K Steel 7ar )sed in str)ct)ral concrete to ro'ide tensilestren:th6

Rei !orci - Stri A hi:h adherence < A= reinforcin: element )sed to add tensilestren:th to the soil in a Reinforced Earth &all6 The A reinforcin: stri is 1* mm &ide

7! % mm thic;( &ith . mm hi:h ri7s on 7oth the to and 7ottom s)rfaces6

Re%i%ti"it5 K Resistance of sat)rated soil to assa:e of electrical c)rrent6

Re%i%ti"e )o e K The re:ion 7ehind the acti'e >one in &hich the shear stress alon: thereinforcin: stri s is directed a&a! from the facin:6

Sacri!icial T#ic e%% K /ortion of a reinforcin: stri s thic;ness e3 ected to 7esacrificed to corrosion d)rin: the desi:n life of the str)ct)re6

Sco&r $rotectio K Sta7ili>ation material s)ch as stone or ri ra laced alon: the 7ase ofa &aterfront str)ct)re to re'ent )nderminin: and colla se from tides or c)rrent6

Select ,ac !ill K 8ac;fill meetin: the h!sico-chemical re )irements s ecified forReinforced Earth &all a lications <also referred to as PGran)lar 8ac;fillP=6

Ser"ice Li!e K The n)m7er of !ears a str)ct)re is e3 ected to remain in ser'ice and f)ll!f)nctional6 S ecificall!( the eriod of time d)rin: &hich the str)ct)ral com onents m)stremain in an allo&a7le stress condition <:enerall! 01 or $** !ears=6

S# K S!m7ol for hori>ontal earth ress)re at s ecific le'el &ithin a &all6

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S#ear %tre -t# K The resistance of a soil to shear6

S#o Dra*i -% K Dra&in:s re ared to sho& the dimensions and materials necessar! tofa7ricate the com onents of a Reinforced Earth &all6

Sli 9oi t K Contin)o)s 'ertical Boint laced in a Reinforced Earth &all to allo&differential settlement &itho)t facin: anel distress( to create a transition from a cast-in- lace to a Reinforced Earth str)ct)re( or to accommodate a small-radi)s c)r'e6

SO K Chemical s!m7ol for s)lfates6

Soil Ce:e t K a mi3t)re of soil and cement )sed to sta7ili>e &ea; soils )nder certainconditions6

Soil Dilate c5 K The tendenc! of a :ran)lar soil to e3 erience a 'ol)me increase d)rin:shearin: of the soil6

S lice $late K Steel late )sed to connect t&o reinforcin: stri s &hen the desi:n len:th isin e3cess of man)fact)rin: limits6

STA,L K Soft&are de'elo ed 7! /)rd)e Uni'ersit! to determine :lo7al sta7ilit! inaccordance &ith 8isho s Modified Method of Slices6

Ste e/ K The )se of anels of 'ar!in: hei:hts at either the 7ase or to of a ReinforcedEarth &all to accommodate ele'ation chan:es6

S" K S!m7ol for 'ertical stress d)e to o'er7)rden soil a7o'e a reinforcement inReinforced Earth 'ol)me6

T B0 K In e'al)ation of consolidation( the time it ta;es for ?* of settlement to occ)r in asoil mass6

Terratrel ® - Wire-faced Reinforced Earth &all s!stem de'elo ed 7! RECo6

Ter7a-#i ,eari - Ca acit5 K Method of determinin: )ltimate 7earin: ca acit! offo)ndation soil6

Tie Stri K Steel anchorin: de'ice cast into recast anel so reinforcin: stri ma! 7e

attached for Reinforced Earth &all constr)ction6

Tiere/ @all% K Reinforced Earth &alls stac;ed ato each other and &ith each hi:her &allste ed 7ac; 7ehind the one 7elo& <rather than a sin:le 'ertical &all face=6

Toe o! @all K /oint at the 7ase of the front face of the Reinforced Earth &all anels atthe to of the le'elin: ad6

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Tra!!ic ,arrier K /recast or cast-in- lace 7arrier laced at to of &all for crash rotection6

Tria;ial Te%t K La7orator! test )sed to determine the .-dimensional shear stren:th ofsoil at a artic)lar normal load and confinin: ress)re( there7! findin: the friction an:le

and cohesion6

Tr&e ,ri/-e A+&t:e t K T! e of Reinforced Earth &all &here the 7rid:e fo)ndation isa s read footin: s) orted directl! on to of the Reinforced Earth 'ol)me6

U it @ei-#t K Densit! of soil or other material6

>ertical I cl&%io K Str)ct)re that e3tends 'erticall! thro):h <Reinforced Earth= 7ac;fill( s)ch as a 7rid:e a7)tment ile( a manhole or a lar:e si:n fo)ndation6

@ic Drai K S!nthetic stri &ith o en assa:e&a!s( installed in soil to relie'e ore

&ater ress)re d)rin: s)rchar:e loadin:6

@i/e La//er A reinforcin: element )sed to add tensile stren:th to the soil in certaint! es of Reinforced Earth &alls6 The &ide ladder is $"* mm <0 in= &ide and formedfrom W0 &ires6

7 K S!m7ol for de th6

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.0 GENERAL DESIGN

%&' Descri(tion of a Reinforced Earth Wall

A Reinforced Earth &all is a coherent :ra'it! mass that can 7e en:ineered to meets ecific loadin: re )irements6 It consists of recast concrete facin: anels( metallic<steel= soil reinforcements and :ran)lar 7ac;fill6 Its stren:th and sta7ilit! are deri'edfrom the frictional interaction 7et&een the :ran)lar 7ac;fill and the reinforcements(res)ltin: in a ermanent and redicta7le 7ond that creates a )ni )e com ositeconstr)ction material6

.1.1 Str&ct&ral A licatio %

Reinforced Earth is )sed in )r7an( r)ral and mo)ntaino)s terrain for

• Retainin: Walls • Sea&alls• 8rid:e A7)tments • S)7mer:ed &alls• Rail&a! Str)ct)res • Tr)c; d)m s• Dams • 8)l; stora:e facilities

.1.2 A/"a ta-e%

The ad'anta:es of Reinforced Earth technolo:! incl)de

• #le)ibilit - Reinforced Earth str)ct)res distri7)te loads o'er com ressi7le soilsand )nsta7le slo es( red)cin: the need for dee fo)ndations

• High load*carr ing ca(abilit + both static and d namic - a lied str)ct)ral loadsare distri7)ted thro):h the com acted :ran)lar fill and earth ress)re loads areresisted 7! the :ra'it! mass

• Ease and s(eed of installation - refa7ricated materials and :ran)lar soil sim lif!constr)ction and minimi>e the im act of 7ad &eather

• ,leasing a((earance - anels ma! 7e :i'en a 'ariet! of architect)ral treatments

• Econom - $1-1* sa'in:s o'er cast-in- lace concrete &alls( de endin: on &allhei:ht and loadin: conditions6

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.1.3 Ser"ice Li!e

What is ser-ice life?

The ser'ice life of a Reinforced Earth str)ct)re is the eriod of time d)rin: &hich thestr)ct)re m)st remain in an allo&a7le stress condition <see Section %6,6% for a morecom lete disc)ssion of ser'ice life=6 Information a7o)t the ser'ice life m)st 7e ro'ided

7! the 4&ner or en:ineer in order for The Reinforced Earth Com an! to ro erl! desi:nthe str)ct)re6 If the ser'ice life is not s ecified( the t! ical 'al)e of 01 !ears &ill 7eass)med6

%&. Design Information Needs

.2.1 $ro ect De%cri tio ?Locatio

What information is needed to la out a Reinforced Earth wall?

• /lan 'ie& sho&in: &all location relati'e to road&a! centerline( 7rid:es( iles(e3istin: retainin: &alls( slo es or other o7Bects6 Ideall!( the lan 'ie& sho)ldincl)de offsets from the face of the &all to the centerline( the 7e:innin: andendin: &all stations( and the road&a! :eometr!6

• Location and si>es of inlets( i es( si:ns and li:ht oles( e3istin: or f)t)re( &hich&ill im act the desi:n of the Reinforced Earth str)ct)re6

• T! ical cross section at the &all location &ith all a ro riate dimensions6

• To of &all ele'ations and 7ottom of &all or finished :rade ele'ations <and2orem7edment criteria=6 +ertical c)r'e and s) erele'ation data and cross sections atthe &all location can s)7stit)te for &all ele'ations6

What details should be (ro-ided in the contract documents regarding a Reinforced Earth wall?

Most details needed to constr)ct a Reinforced Earth &all &ill 7e ro'ided in the &all lans re ared 7! RECo6 Details re:ardin: draina:e( ill)mination( si:n s) orts and toof &all a )rtenances sho)ld 7e ro'ided 7! the 4&ner in the contract doc)ments6

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.2.2 Geotec# ical Re ort

What is the im(ortance of a geotechnical re(ort in the design of a Reinforced Earthstructure?

Geotechnical information is critical to e'al)atin: fo)ndation conditions for an! str)ct)re(e'en a fle3i7le one li;e a Reinforced Earth &all6 As al&a!s( the more com lete and

7etter )alit! the :eotechnical data( the less conser'ati'e and more economical thefo)ndation desi:n can 7e( and the str)ct)re itself can reflect this econom! as &ell6 This ises eciall! tr)e in these sit)ations

• When &ea; soils )nderlie the roBect site6 In s)ch sit)ations( a Reinforced Earth&all is often an economical choice s ecificall! 7eca)se it is fle3i7le and can adB)stto the settlement that sometimes occ)rs &ith &ea; soils( eliminatin: the need fordee or massi'e fo)ndations intended to ro'ide ri:idit!6

• When the Reinforced Earth str)ct)re &ill s) ort a deformation-sensiti'e str)ct)res)ch as a 7rid:e a7)tment6 It is often more economical to ma;e <at least the ends an of= a 7rid:e s) erstr)ct)re fle3i7le than it is to ma;e the s)7str)ct)re ri:id6Th)s( ha'in: :ood :eotechnical data is critical to ma;in: informed str)ct)re desi:ndecisions6

These sit)ations and others are disc)ssed in more detail in Section 0( Fo)ndationConsiderations6 The 7ottom line( ho&e'er( is that more <rather than less= :eotechnicalinformation is al&a!s a &ise in'estment6

What t (e of information is needed from a geotechnical re(ort?

A :eotechnical re ort sho)ld ro'ide s ecific information a7o)t the conditions at the roBect site6 T! icall!( 7orin:s sho)ld 7e ta;en to a de th $61 to , times the &all hei:ht(or to 7edroc;( &hiche'er is enco)ntered first6 The! sho)ld 7e located at no :reater than±#* m <,** ft= inter'als and2or near the ends of each str)ct)re6 Closer s acin: or :reaterde th of 7orin:s ma! 7e re )ired 7! field conditions or 4&ner s ecifications6 Ali:nmentof 7orin:s alon: <or sli:htl! 7ehind= the ro osed &all face is referred6

In the case of &ea; fo)ndation soils( shear stren:th and settlement characteristics are ofmaBor im ortance6 If these characteristics are &ell defined in the :eotechnical re ort( theRECo desi:ner &ill not 7e forced to ma;e conser'ati'e ass)m tions6 For more s ecificrecommendations on the s)7s)rface soil e3 loration and la7orator! testin: ro:ram( seeReference 16

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What is the relationshi( between the coefficient of sliding and the friction angle of the foundation soil?

Most :eotechnical re orts ro'ide information a7o)t the coefficient of slidin: 7et&eenthe ro osed footin: concrete and the )nderl!in: soil( to 7e )sed for desi:nin: traditionalreinforced concrete retainin: &alls6 For slidin: of a Reinforced Earth &all to occ)r(ho&e'er( a slidin: lane m)st de'elo either 7et&een the Reinforced Earth 7ac;fill andthe fo)ndation soil( or totall! &ithin the fo)ndation soil itself6 Therefore( the frictionan:les of 7oth the Reinforced Earth 7ac;fill and the fo)ndation soil m)st 7e ;no&n6 Areasona7le estimate of the friction an:le of the s ecified Reinforced Earth 7ac;fill can 7emade 7ased on e3 erience &ith other materials com l!in: &ith the same :ran)lars ecification( 7)t la7orator! testin: is re )ired to determine the friction an:le <shearstren:th= and cohesion of the <site-s ecific= fo)ndation soil6

How is E/ui-alent #luid ,ressure used in the design of Reinforced Earth walls?

E )i'alent fl)id ress)re( a conce t )sed in the desi:n of concrete retainin: &alls( is notapplicable to the design of Reinforced Earth walls 6 Reinforced Earth desi:n roced)resre )ire calc)lation of the act)al 'ertical and hori>ontal earth ress)res to determine theload carried 7! the reinforcin: stri s and the ress)re at the 7ac; face of the &all6

.2.3 Nor:al $ool?Floo/ Le"el%

What is the im(ortance of (ool ele-ation and0or flood le-el information for a

Reinforced Earth structure?

Information a7o)t normal ool and flood le'els is of maBor im ortance6 If the str)ct)re is artiall! or s)7stantiall! s)7mer:ed( 7)o!ant forces m)st 7e acco)nted for in desi:n6Under these circ)mstances( a Reinforced Earth str)ct)re &ill e3ert less ress)re on thes)7soil( there7! red)cin: the factors of safet! a:ainst slidin: and o'ert)rnin:6 Therefore(a s)7mer:ed condition affects the o'erall sta7ilit! of a Reinforced Earth str)ct)re andm)st 7e acco)nted for in desi:n6

What is a 1(eriodicall submerged1 structure?

/eriodicall! s)7mer:ed Reinforced Earth str)ct)res are those s)7Bect to eriodic fresh&ater floodin:( &ith the c)m)lati'e s)7mer:ed time no more than t&o &ee;s er !ear6In this sit)ation( the Reinforced Earth str)ct)re is desi:ned &ith draina:e feat)resa ro riate to the $**-!ear <or other s ecified= flood condition( as disc)ssed in the ne3t

ara:ra h6 Additional information on s)7mer:ence and h!drostatic loadin: is containedin Section %6.6.6

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In a ra id dra&do&n sit)ation < ool ele'ation dro s faster than &ater can flo& o)tthro):h the anel Boints=( &ater tem oraril! tra ed 7ehind the &all anels can create an)n7alanced head condition and red)ce the factor of safet! in relati'el! fine-:rained<sand! to silt!= 7ac;fills6 For s)ch str)ct)res alon: ri'ers and canals( AAS T4 Section16"6$,6. re )ires that a minim)m differential h!drostatic ress)re e )al to $6* m <.6. ft=

of &ater 7e considered in desi:n6

To red)ce ro7lems associated &ith s)7mer:ence( it is recommended to )se com letel!free drainin: <coarse= select 7ac;fill for s)ch Reinforced Earth str)ct)res6 This 7ac;fill

ro'ides the additional ad'anta:e of hi:h shear stren:th( increasin: the desi:n factors ofsafet! for slidin: and reinforcement )llo)t6 Sco)r rotection sho)ld 7e ro'ided in frontof the str)ct)re( 7ased on the 4&ner-determined sco)r de th6

.2. Ser"ice Li!e

What is ser-ice life?

As re'io)sl! defined in Section %6$6.( the ser'ice life of a Reinforced Earth str)ct)re isthe eriod of time d)rin: &hich the str)ct)re m)st remain in an allo&a7le stresscondition6 E'en at the end of the ser'ice life( an allo&a7le stress condition is ass)red forcontin)ed safe f)nctionin: of the str)ct)re <Reference $=6

How is the ser-ice life of a Reinforced Earth wall determined?

The 4&ner <or the 4&ner s en:ineer= determines the ser'ice life re )ired 7ased on thestr)ct)re t! e and a realistic assessment of f)nctional( safet! and economic factors6 Fortrans ortation str)ct)res( the ser'ice life is set 7! AAS T4 s ecifications at 01 or $**!ears <see ne3t ara:ra h=6 Se'ent!-fi'e !ears is also the t! ical ser'ice life forinfrastr)ct)re and commercial roBects and( if not :i'en a ser'ice life re )irement( TheReinforced Earth Com an! )ses 01 !ears6

What is a (ermanent structure? A critical structure?

A per anent Reinforced Earth str)ct)re is defined as one ha'in: a 01-!ear ser'ice life6This definition has e'ol'ed thro):h ractice and is no& re )ired 7! s ecification6 Mostretainin: &alls are considered ermanent str)ct)res( incl)din: not onl! those in marineen'ironments( 7)t also so-called PfalseP 7rid:e a7)tments &here the 7rid:e seat sits on

iles that e3tend do&n thro):h the Reinforced Earth 7ac;fill6

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!ritical Reinforced Earth str)ct)res are those s) ortin: )n)s)all! hea'! loads orstr)ct)res for &hich loss of str)ct)ral f)nction &o)ld ose intolera7le ris; to life and2or

ro ert!6 8! definition( a critical str)ct)re has a ser'ice life of $** !ears6 E3am les ofcritical str)ct)res incl)de s read footin: <tr)e= 7rid:e a7)tments( &here the 7eam seat

7ears directl! on the Reinforced Earth 7ac;fill <no iles are )sed=( and &alls s) ortin:

railroads6 As descri7ed a7o'e( the 4&ner ma;es the final decision &ith res ect to theser'ice life or criticalit! of a Reinforced Earth str)ct)re6

What is a tem(orar Reinforced Earth structure?

A tem orar! Reinforced Earth str)ct)re :enerall! has a ser'ice life of less than $* !earsand often as little as $ to . !ears6 For these str)ct)res( RECo en:ineers )se a ro riatecorrosion models and desi:n arameter 'al)es to ens)re that the str)ct)re &ill remain inan allo&a7le stress condition thro):ho)t the re )ired ser'ice life6

How does the ser-ice life influence the design?

A corrosion model has 7een de'elo ed 7ased on o'er 01 !ears of field and la7orator!data on the erformance of 7)ried :al'ani>ed steel <Reference ,( Reference .=6Reinforced Earth en:ineers ;no& the metal loss rates for 7oth the >inc <:al'ani>ation=and the )nderl!in: car7on steel( and can calc)late the metal thic;ness that &ill 7esacrificed to corrosion d)rin: an! s ecified ser'ice life <the sacrificial thic"ness =6Therefore( the desi:n thic;ness of the reinforcin: stri is the nominal thic;ness min)s thesacrificial thic;ness <Reference %=6

%&2 3oading 4onditions

What loads need to be considered for design of RE walls? Who (ro-ides this data?

Reinforced Earth &alls are considered to act as :ra'it! retainin: str)ct)res( &ith theadded 7enefit of accommodatin: s)7stantial total and differential settlement <see alsoSection 0 for a disc)ssion of settlement=6 As :ra'it! retainin: str)ct)res( ReinforcedEarth &alls ma! 7e desi:ned for most of the same loadin: conditions as are t! icall!associated &ith con'entional cast-in- lace str)ct)res6 The distri7)tion of the 'ario)sloads de ends on the :eometr! of each &all and the t! e of load( as disc)ssed in thefollo&in: s)7sections6

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.3.1 Static Loa/%

As is the case &ith an! :ra'it! retainin: &all( the lateral earth ress)re ind)ced 7! theretained non-reinforced earth mass m)st 7e resisted 7! the mass of the Reinforced Earth

'ol)me <Reference 0=6 Similarl!( the fo)ndation soils 7eneath the &all m)st 7e a7le tos) ort the 'ertical loads im osed 7! the reinforced mass( incl)din: an! s)rchar:e loadss)ch as from traffic or 7rid:e a7)tment footin:s s) orted on the Reinforced Earth'ol)me6 The :eometr! of the slo e a7o'e the &all &ill also infl)ence the static loadcondition to 7e e'al)ated <Fi:)re %6.6$6$=6 In :eneral( the 4&ner or Cons)ltant sho)ldha'e the information a'aila7le to assess static load conditions &ith res ect to theReinforced Earth &all( incl)din: 7asic &all :eometr!( s)rchar:e loads( and 7ac;filldensit!6 Some of this information ma! 7e a'aila7le from State De artment ofTrans ortation s ecifications or desi:n :)idelines for Mechanicall! Sta7ili>ed Earth<MSE= str)ct)res6

.3.2 Sei%:ic Loa/%

The seismic ha>ard in the United States 'aries from lo& to hi:h de endin: on the art ofthe co)ntr! 7ein: considered6 Fo)r seismic erformance cate:ories <A thro):h D= aredefined in the AAS T4 s ecifications <Reference "=( 7ased on an accelerationcoefficient for the site and an im ortance classification related to the intended )se of thestr)ct)re6

The acceleration coefficient is o7tained from a ma in the AAS T4 s ecifications

<re rod)ced here as Fi:)re %6.6,6$=( )nless other&ise s ecified 7! the 4&ner6 Anim ortance classification is also defined in AAS T4 for roBect t! es &ith anacceleration coefficient :reater than *6,?6 Reinforced Earth &alls are desi:ned to resisthori>ontal dis lacement )nder seismic loadin: conditions as sho&n in Fi:)re %6.6,6,6

.3.3 S ecial Loa/i - Co /itio %

Reinforced Earth &alls alon: ri'ers and canals need to 7e e'al)ated for the additionalload im osed 7! h!drostatic ress)re6 This additional load is d)e to the head differential

across the Reinforced Earth facin:( that is( the difference in ele'ation 7et&een the &atero)tside the &all and the &ater inside the :ran)lar 7ac;fill of the str)ct)re6 A minim)mdifferential h!drostatic ress)re e )al to . ft of &ater is recommended for desi:n6 Theload is t! icall! a lied at the hi:h-&ater le'el <this information s) lied 7! the 4&ner=(as sho&n in Fi:)re %6.6.6$6 See Section %6,6. for f)rther information on normal andflood conditions6

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Traffic 7arriers installed on a Reinforced Earth &all m)st 7e desi:ned for 'ehic)larim act loadin:6 The force deli'ered to the traffic 7arrier m)st 7e transferred to thereinforcin: stri s as sho&n in Fi:)re %6.6.6,6 Im act loads are :enerall! dictated 7! StateDe artment of Trans ortation re )irements6

No s ecial considerations are necessar! &ith lo&-le'el 'i7rator! loads( s)ch as from'ehic)lar traffic or railroads6 Constr)ction loads are controlled 7! ;ee in: hea'!e )i ment at least $ m <. ft= from the &all face and allo&in: onl! li:ht&ei:ht e )i ment&ithin this >one for com action of 7ac;fill <Reference ?=6 Ideall!( ile dri'in: or othershoc;2'i7ration loadin: sho)ld 7e cond)cted at least .* m <$** ft= from a ReinforcedEarth &all6 Where ile dri'in: m)st 7e closer than .* m( the &all sho)ld 7e monitoredfor 'i7ration-ind)ced dist)r7ance6 /ile installation sho)ld not 7e allo&ed &ithin thereinforced 'ol)me e3ce t )nder redetermined and caref)ll! controlled conditions6

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REFERENCES

$6 Technical 8)lletin MSE-$( Ser'ice Life( Allo&a7le Reinforcement Stress and MetalLoss Rates to 7e Used in the Desi:n of /ermanent MSE Str)ct)res( The Reinforced

Earth Com an!( $??,( re'ised $??16

,6 In Sit) Soil Im ro'ement Techni )es ( AAS T4-AGC-ART8A @oint Committee(S)7committee on Ne& i:h&a! Materials( Tas; Force ,0 Re ort( $??* 6 $%-$16

.6 D)ra7ilit!2Corrosion of Soil Reinforcement Str)ct)res ( Federal i:h&a!Administration Re ort F WA-RD-"?-$"#( $??*6

%6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials $??# <Si3teenth Edition=( $??" Interim(

Di'ision I K Desi:n( Section 16"6#6$6$6

16 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16.6

#6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials $??# <Si3teenth Edition=( $??" Interim(

Di'ision II - Constr)ction( Section 06.6#6.6

06 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16"6,6

"6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16"6?6

?6 Constr)ction and )alit! Control Man)al for Reinforced Earth Str)ct)res ( TheReinforced Earth Com an!( $??#( Section D - 8ac;fillin:( a:es $.-$%6

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.0 MATERIALS

5&' 6ac$fill

A Reinforced Earth str)ct)re consists of com acted :ran)lar 7ac;fill interla!ered &ithreinforcin: stri s that are connected to facin: elements6 This com osite mass retainscom acted random 7ac;fill as sho&n in Fi:)re 16$6$( and the ro erties of 7oth the selectand the random 7ac;fills ha'e a si:nificant im act on the desi:n of the Reinforced Earthstr)ct)re6 Desi:n ro erties of the select and random 7ac;fills are )s)all! determined 7!local en:ineers 7ased on their e3 erience &ith similar materials( 7)t in some sit)ations(RECo s e3 erienced en:ineerin: rofessionals ha'e assisted 4&ners and theirCons)ltants in the e'al)ation of these material ro erties6

The h!sico-chemical re )irements for select 7ac;fill &ere de'elo ed 7ased on:eotechnical rinci les and e3tensi'e research on the 7eha'ior of 7ac;fill materials( &ith

fine-t)nin: 7! caref)l monitorin: of the erformance of n)mero)s in-ser'ice str)ct)resaro)nd the &orld6 Therefore( &e )nderstand that redicta7le 7eha'ior 7! the constr)ctedReinforced Earth str)ct)re can 7e ass)red if the ro erties of the Reinforced Earth select

7ac;fill fall &ithin certain &ell-defined limits6 4f co)rse( the ro erties of the random 7ac;fill &ill 'ar! from roBect to roBect( de endin: on local conditions( 7)t &ith;no&led:e of these ro erties( the forces e3erted 7! the random 7ac;fill can easil! 7eincor orated into the Reinforced Earth desi:n6

.1.1 Select ,ac !ill

What are the general (erformance re/uirements for select bac$fill?

S ecifications for Reinforced Earth select 7ac;fill are t! icall! re ared 7! the 4&ner(the Cons)ltant( or 7! RECo en:ineers( 7ased on roBect-s ecific re )irements6 8ac;fillselection also re )ires consideration of the relati'e economies of im orted 'ers)s locall!a'aila7le materials( re'io)s e3 erience &ith similar materials( and local constr)ction

ractice6 Reinforced Earth select 7ac;fill ma! 7e a nat)ral soil and roc; material( arec!cled material( or an ind)strial 7!- rod)ct6

All select 7ac;fill material( no matter &hat its ori:in( m)st meet the follo&in: :eneral

erformance re )irements

• The material m)st 7e &ell drained(

• The material m)st not 7e rone to ost-constr)ction mo'ement d)e to cree (

• The material m)st 7e d)ra7le and not 7rea; do&n or chan:e its ro erties d)rin:constr)ction( and

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• The material m)st not 7e a::ressi'e to :al'ani>ed steel6

What are the minimum (h sico*chemical re/uirements for select bac$fill?

8ased on statistical anal!sis of roBects thro):ho)t the &orld( RECo has fo)nd thata ro3imatel! ?1 of the 7ac;fill materials that meet the h!sical re )irements forReinforced Earth str)ct)res also meet the Reinforced Earth electrochemical re )irements6The electrochemical ro erties of ind)strial 7!- rod)ct 7ac;fills m)st 7e caref)ll!e'al)ated in e'er! instance( ho&e'er( since the ro erties of these materials de end ondetails of the man)fact)rin: rocess and ma! 'ar! si:nificantl! from material to materialand from re:ion to re:ion6

In :eneral( select 7ac;fill materials sho)ld meet the re )irements and conform to thes ecifications sho&n in Ta7le 16$6$6 In 'er! s ecial circ)mstances( e3ce tions ma! 7emade to these re )irements after caref)l re'ie& 7! a RECo en:ineer6

How does the beha-ior of a Reinforced Earth structure change if the amount of finesin the select bac$fill increases?

Altho):h the standard s ecification for Reinforced Earth select 7ac;fill re )ires less thanor e )al to $1 assin: the *6*01 mm <No6 ,**= sie'e( materials &ith ) to %* assin:

a# be considered $nder li ited circ$ stances and after caref$l testing 6 The 4&ner2Cons)ltant m)st &ei:h the otential cost ad'anta:e of )sin: s)ch fine-:rained 7ac;filla:ainst the ossi7l! si:nificant increase in the n)m7er and len:th of steel reinforcementsre )ired( as &ell as the res)ltin: increase in the Reinforced Earth 7ac;fill 'ol)me6 Inorder to B)stif! )sin: a soil &ith :reater than $1 fines as select 7ac;fill( the desi:nerm)st e'al)ate short term sta7ilit! factors( incl)din: sat)ration2draina:e 7eha'ior( andde'elo constr)ction roced)res a ro riate to that material6 %nder no circ$ stances

sho$ld a bac"fill with greater than 15& fines be $sed in a periodicall# s$b erged str$ct$re <see Section %6,6.=6

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TA8LE 16$6$

SELECT 8ACHFILL RE UIREMENTS AND TEST MET 4DS

Select 8ac;fill Re )irements<AAS T4 S ecification - Reference $=

Test Method<AAS T4=

Test Method<ASTM=

'eotechnical /article si>e ≤ $1* mm <# in= T ,0 D %,,Amo)nt assin: the *6*01 mm <No6 ,**= sie'e ≤ $1 T ,0 D %,,/lasticit! inde3 ≤ # T ?* D %.$"An:le of internal friction φ ≥ .%Q T ,.# J D .*"*The material shall 7e essentiall! free of or:anic andother deleterio)s materials

None D ,?0%

The material shall 7e essentiall! free of oord)ra7ilit! articles( and the ma:nesi)m s)lfateso)ndness loss shall 7e less than .* after fo)r c!cles

T $*% none

Electroche ical 7et&een 1 and $* T ,"?-?$ I G1$Resisti'it! <at $** sat)ration= > .*** ohm-cm T ,""-?$ I G10Water sol)7le chloride content < $** m T ,?$-?$ I D1$,Water sol)7le s)lfate content < ,** m T ,?*-?$ I D1$#

J Test to 7e erformed on the ortion finer than the , mm <No6 $*= sie'e( )tili>in: a sam leof the material com acted to ?1 of AAS T4 T ??( Methods C or D <&ith o'ersi>ecorrection as o)tlined in note 0= at o tim)m moist)re content6

.1.2 Ra /o: ,ac !ill

What is random bac$fill?

As sho&n in Fi:)re 16$6$( random 7ac;fill is the soil retained 7! the Reinforced Earthstr)ct)re <the soil behind the Reinforced Earth 'ol)me=6 Random 7ac;fill ma! 7e:ran)lar or cohesi'e soil( cr)shed roc;( ind)strial 7!- rod)cts or rec!cled materials6

How are design (arameters and earth (ressure coefficients determined for randombac$fill?

The shear stren:th ro erties <friction an:le and cohesion= and the )nit &ei:ht of therandom 7ac;fill are )sed to e'al)ate the ress)re e3erted at the 7ac; of the ReinforcedEarth 'ol)me6 Shear stren:th ro erties of random 7ac;fills are :enerall! ro'ided 7!

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the roBect Geotechnical Cons)ltant 7ased on familiarit! &ith local :eolo:! and similarmaterials6 When these arameters m)st 7e de'elo ed in the la7orator!( tests s)ch as thedirect shear test <ASTM D .*"*= and2or the )nconsolidated )ndrained tria3ial test &ith

ore ress)re meas)rements <ASTM D %0#0= are cond)cted as art of the roBect:eotechnical e3 loration6

How are strength (arameters determined if the random bac$fill is a stiff cohesi-e soil?

Finite element st)dies and meas)rements on f)ll-scale Reinforced Earth str)ct)res ha'esho&n that the ress)re e3erted at the 7ac; of the str)ct)re corres onds closel! to theacti'e state6 Therefore the ress)re at the 7ac; of the str)ct)re can 7e calc)lated 7asedon the coefficient of acti'e earth ress)re( H a( the )nit &ei:ht of the random 7ac;fill( andthe ma:nit)de of an! s)rchar:e loads6

In the case of Reinforced Earth str)ct)res constr)cted a:ainst stee c)ts into 'er!cohesi'e soils( the lon: term shear stren:th ro erties of those soils sho)ld 7e )sed toe'al)ate the earth ress)re forces6 Altho):h the short term stren:th of a stiff cohesi'esoil is )s)all! hi:h eno):h that the material can stand 7! itself d)rin: constr)ction(desi:n arameters &hich consider the :eolo:ic ori:in of s)ch materials &ill ro'ide a

7etter indication of the earth ress)re e3 ected d)rin: the life of the str)ct)re6

.1.3 Ra /o: ,ac !ill $lace/ A-ai %t a C&t Slo e

When the random 7ac;fill &ed:e is 'er! narro& near the lo&er ortion of the ReinforcedEarth 'ol)me( it ma! 7e more cost-effecti'e to lace select 7ac;fill 7e!ond the end of thereinforcin: stri s and all the &a! 7ac; to the face of the e3ca'ated slo e( rather thantr!in: to lace and com act random 7ac;fill in this narro& area6 /lacement of the t&o

7ac;fill t! es in their res ecti'e >ones ma! commence once the str)ct)re is hi:h eno):h(and the random 7ac;fill &ed:e &ide eno):h( to ermit economical lacement o erationsfor each material6

Man! contractors reco:ni>e the increased cost of lacin: and com actin: a narro&&ed:e of random 7ac;fill( 'ie&in: the easier lacement of select 7ac;fill as aneconomical trade-off a:ainst the select material s hi:her cost6 This ractice is t! icall! atthe contractor s discretion( 7)t the 4&ner or en:ineer is also free to s ecif! this

7ac;fillin: method( in &hich case the additional select 7ac;fill sho)ld 7e incl)ded in the 7id )antit!6

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5&. Reinforcing Steel

What t (e of reinforcement is used in the Reinforced Earth -olume? What is meant bthe term 1ine)tensible1?

Reinforced Earth &alls )se ine3tensi7le steel reinforcements in the reinforced 'ol)me6The term Pine3tensi7leP refers to a t! e of MSE reinforcement( t! icall! :al'ani>ed steel(&hich deforms m)ch less readil! than the 7ac;fill that en'elo s the reinforcement6RECo c)rrentl! )ses t&o main reinforcement t! es

• Stri s - 1* mm &ide hi:h adherence < A= ri77ed stri s <Fi:)re 16,6$= and

• Ladders - $** mm &ide A ladders <Fi:)re 16,6,=( and $"* mm &ide ladders<Fi:)re 16,6.=6

These reinforcements 'ar! in their tensile ca acit! and )llo)t ca acit!6 The follo&in:s)7sections disc)ss the characteristics of the steel reinforcin: s!stems )sed in ReinforcedEarth &alls6

.2.1 Te %ile Ca acit5

What is the ca(acit of the reinforcement?

Ri77ed reinforcin: stri s are hot rolled from 7ars to the re )ired sha e and dimensions6The steel )sed in the reinforcin: stri s conforms to ASTM A-10, Grade #1 <AAS T4M-,,.=6 Allo&a7le tensile ca acit! of the ri77ed stri s can 7e determined in a 'ariet! of&a!s de endin: ) on &hether AAS T4 <Reference ,=( indi'id)al State De artment ofTrans ortation or other codes are follo&ed6 The allo&a7le ca acit! is t! icall! 7ased onthe :ross area of the ri77ed stri ( the s ecified factor of safet!( and the net area of thestri after red)ction for corrosion losses6

Reinforcin: ladders <7oth A ladders and &ide ladders= are man)fact)red from colddra&n steel &ire conformin: to ASTM A-", Grade #1 and &elded in accordance &ithASTM A-$"16 Allo&a7le tensile ca acit! for ladders is determined in the same manneras for ri77ed reinforcin: stri s( i.e. ( calc)lations are made 7! e'al)atin: the stress in thelon:it)dinal &ires after red)cin: the cross section to acco)nt for corrosion losses6

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.2.2 $&llo&t Ca acit5

/)llo)t ca acit! <Reference .= de ends on the frictional interaction 7et&een thereinforcements and the 7ac;fill &ithin the reinforced 'ol)me6 It is calc)lated as follo&s

/ fJ γ >As

&here

/ )llo)t ca acit!fJ friction factor γ 7ac;fill densit!> de th of reinforcementA s cross-sectional area of reinforcement

<net( after acco)ntin: for corrosion loss=

+al)es for fJ 'ar! de endin: on the t! e of 7ac;fill )sed in the reinforced 'ol)me( asdisc)ssed in Section 16$6 For ri77ed stri s and A ladders( friction factor 'al)es are

7ased ) on e3tensi'e la7orator! )llo)t testin: cond)cted 7! RECo6 A ladders e3hi7it )llo)t 7eha'ior similar to that of ri77ed stri s 7eca)se the ladder s cross 7ars are closel!and )niforml! s aced <e'er! $1* mm <# in==6 8! com arison( cross 7ar s acin: on &ideladders 'aries from $1* to #** mm <# to ,% in=( ma;in: &ide ladders 7eha'e as &ire matreinforcement rather than as stri reinforcement6

.2.3 D&ra+ilit5

How durable are the reinforcements?

The d)ra7ilit! of :al'ani>ed steel earth reinforcements de ends on the electrochemical ro erties of 7oth the reinforcements and the reinforced 7ac;fill6 Corrosion of:al'ani>ed steel has 7een st)died e3tensi'el! for more than #* !ears in a 'ariet! ofen'ironments( !ieldin: a lar:e 7od! of data from &hich ha'e 7een de'elo edconser'ati'e metal loss rates )sed for desi:n of Reinforced Earth &alls <Reference %=6

Gal'ani>ation is a sacrificial coatin: of >inc( acti'el! rotectin: the )nderl!in: steel as it<the >inc= is cons)med( then ro'idin: resid)al assi'e rotection d)e to corrosion

7! rod)cts left on the steel and in the immediatel! s)rro)ndin: soil6 We ;no& the rate at&hich the :al'ani>ation is cons)med and the rate at &hich the )nderl!in: steel corrodesonce the >inc is :one( so it is a sim le calc)lation to determine a str)ct)re s e3 ected life6Con'ersel!( :i'en a ser'ice life re )irement <t! icall! 01 !ears for ermanent str)ct)res($** !ears for critical str)ct)res( see Section %6$6.=( the amo)nt of steel re )ired toachie'e that ser'ice life can also 7e calc)lated6

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/racticall! s ea;in:( reinforcin: stri s are man)fact)red in a sin:le( standard crosssection and desi:n re )irements are met 7! 'ar!in: the n$ ber rather than the si e of thereinforcements6 The desi:n rocess ta;es into acco)nt the ma3im)m stress eachreinforcement can carr! :i'en the roBect s ser'ice life re )irement and the metal lossrates disc)ssed a7o'e6

The 7ac;fill characteristics that affect the ser'ice life of 7)ried :al'ani>ed steel are (soil resisti'it! at $** sat)ration( and the le'els of dissol'ed s)lfate and chloride ions6S)7mer:ence in fresh or salt &ater increases the otential for corrosion loss( 7)ts)7mer:ed 7eha'ior is &ell )nderstood and desi:n adB)stments can 7e made to rod)cesafe and d)ra7le str)ct)res6 For normal dr!-land constr)ction( the acce ta7le ran:es for

( resisti'it!( chlorides and s)lfates are <re eated here from Ta7le 16$6$=

• 1 - $*• Resisti'it! > .*** ohm-cm• Chlorides < $** m

• S)lfates < ,** m6

Tem orar! Reinforced Earth &alls :enerall! consist of &ire facin: and 7lac;<)n:al'ani>ed= steel reinforcements6 Corrosion ser'ice life calc)lations( &hen re )iredfor tem orar! str)ct)res( are erformed on a case-s ecific 7asis6

Corrosion-resistant coatin:s other than :al'ani>ation ma! 7e considered( artic)larl! for)se in a::ressi'e 7ac;fills and marine en'ironments &here :al'ani>ed steel ma! not 7ethe 7est choice6 Resin-7onded e o3! is one s)ch material( a lied to a minim)mthic;ness of *6% mm <$# mils= in accordance &ith AAS T4 M,"%6 This coatin: is not$** relia7le( ho&e'er( d)e to the ris; of constr)ction dama:e &hen )sin: :ran)lar<es eciall! coarse= 7ac;fills6 E'en small enetrations of an e o3! coatin: in &idel!s aced areas of the reinforcement can create a ro7lem( since corrosion tends toconcentrate more a::ressi'el! at these locations &here moist)re and o3!:en can :et tothe )nderl!in: metal( &ith the corrosion s readin: )ndetected 7eneath the coatin:6

A ne& coatin: de'elo ed 7! RECo )nder the name PD)noisP com7ines >inc andal)min)m and offers s) erior d)ra7ilit! in a::ressi'e 7ac;fill and marine en'ironments6The D)nois coatin: has )nder:one ,* !ears of testin: 7! RECo and is c)rrentl! 7ein:)sed in demonstration roBects in the United States6 D)nois is a thermal s ra!ed coatin:&hich( &hen a lied( forms a microsco ic matri3 of al)min)m in &hich the s aces&ithin the matri3 are filled &ith >inc6 The matri3 str)ct)re ro'ides s) erior resistance

to constr)ction dama:e6 Test res)lts sho& that this interloc;ed >inc2al)min)m coatin:does not a recia7l! de lete o'er time( ro'idin: a rotecti'e coatin: in almost all &allen'ironments &ith the e3ce tion of those &hich are hi:hl! al;aline <a::ressi'e toal)min)m=6 Thermal s ra!ed coatin:s are onl! economical for stri -t! e reinforcements(ho&e'er( since m)ch of the s ra! is lost &hile 7ein: a lied to the &ires of A and &ideladder reinforcements6

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5&2 #acings

What t (es of facings are a-ailable for Reinforced Earth walls?

Reinforced Earth &alls can 7e constr)cted &ith an! of three maBor facin: t! es reca%ta el%( *ire !aci -% and co crete :a%o r5 +loc % 6 Since the facin: is the onl! 'isi7le

feat)re of a Reinforced Earth &all( selection of the ri:ht facin: t! e( incl)din: si>e(sha e( color and te3t)re( is an im ortant desi:n decision6

$reca%t co crete a el% are the most common facin: elements )sed for ermanentstr)ct)res6 The! are installed 'erticall!( altho):h a 7atter of 1Q-$*Q ma! 7e ermitted inli ited and caref$ll# considered sit$ations 6 The anels ma! 7e cast in cr)ciform <Fi:)re16.6$=( rectan:)lar <Fi:)re 16.6,= or s )are <Fi:)re 16.6.= sha es to meet roBecten:ineerin: and aesthetic re )irements6

When ) to $ differential settlement is e3 ected alon: the len:th of the &all <Section06%=( the cr)ciform anel is the 7est choice 7eca)se of its Boint desi:n and anel ed:e li 6Where more than $ differential settlement m)st 7e accommodated( 'ertical sli Bointsare ro'ided( t! icall! located e'er! $* to ,* anels alon: the &all len:th <Section ?6$=6

,loc !aci - <Fi:)re 16.6%= ma! 7e a ro riate in certain ermanent &all a lications(es eciall! &here 7atter of as m)ch as $1Q is re )ired6 o&e'er( 7loc;s ha'e a smaller)nit area and re )ire more effort not onl! to constr)ct( 7)t also to ali:n and ;ee ali:nedd)rin: constr)ction <as com ared to the si:nificantl! lar:er recast anels=6 In addition(

7loc; facin:s do not ha'e o en Boints 7et&een 7loc;s( res)ltin: in direct 7loc;-to-7loc;contact and( therefore( 'irt)all! no tolerance for differential settlement6 8loc; facin:s

sho)ld not 7e )sed &here differential settlement is e3 ected6

For tem orar! &alls( si:nificant econom! ma! 7e reali>ed thro):h the )se of fle3i7le&ire facin: <Fi:)re 16.61=6 The fle3i7ilit! of the &ire mesh allo&s the facin: to deformand effecti'el! accommodate lar:e settlements6 In addition( the &ire facin: ma! 7econ'erted to a ermanent facin: after rimar! settlement and deflections ha'e occ)rred(either 7! )sin: cast-in- lace concrete or 7! attachin: recast concrete anels6 Altho):hless economical than a Reinforced Earth &all 7)ilt onl! )sin: recast anels( thetem orar!-to- ermanent &ire face s!stem ma! 7e B)stified &here si:nificant total anddifferential settlement is antici ated6

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5&% 4onnections

How are the Reinforced Earth wall facings attached to the reinforcing stri(s in thereinforced -olume?

Each facin: t! e )ses a different method for attachin: the reinforcements6 /recast anelsha'e a tie stri cast into the 7ac; face and )se a sin:le A.,1 7olt actin: in do)7le shear6The reinforcin: stri or A ladder is held 7et&een the to and 7ottom lates of the tiestri <Fi:)res 16%6$( 16%6,=( and the connection is made &ith the 7olt6

In the case of 7loc; facin:( 'ertical holes are formed in the to and 7ottom of each 7loc;d)rin: recastin: o erations6 Gal'ani>ed steel ins are inserted in the holes and the endloo s of a &ide ladder reinforcement are laced o'er the ins to ma;e a ositi'econnection <Fi:)re 16%6.=6

Wire facin:s )se either a handle7ar connector <Fi:)re 16%6%= to accommodate re:)larladder reinforcements( or a hair in connector <slotted 'ersion( Fi:)re 16%61= for Aladder or ri77ed stri reinforcements6 The handle7ar is &o'en thro):h the &ire facin:d)rin: constr)ction and the t&o free ends en:a:e the loo s of the re:)lar ladder B)st asthe :al'ani>ed ins do in the 7loc; facin: disc)ssed a7o'e6 The hair in <&ith a slot( assho&n in Fi:)re 16%61=( &ra s aro)nd the do)7le hori>ontal &ire of the &ire facin: aneland connects to the ri77ed stri or A ladder 7! a 7olt inserted thro):h holes in thehair in6

The slotted 'ersion of the hair in also allo&s an additional connection from the front faceof the &ire-facin: anel for attachin: a recast anel <Fi:)re 16%6#=6 The s ace 7et&een

anels is :enerall! filled &ith o en-:raded ,* - ,1 mm < - $ in= a::re:ate6 This slotma! also ser'e as the anchora:e oint for con'entional reinforcin: 7ars in a cast-in- laceconcrete facin: <Section 16.=6

5&5 6earing ,ads

How is s(alling or damage to the concrete (re-ented at 7oints between (recast concrete (anels?

Earl! Reinforced Earth constr)ction )tili>ed stri s of resin-7onded cor; to ro'ide ahori>ontal 7earin: c)shion 7et&een the to of one anel and the 7ottom of the anela7o'e6 This material ro'ed to 7e s)7Bect to )ndesira7le com ression( ho&e'er(occasionall! allo&in: clos)re of the hori>ontal Boints 7et&een anels6 Altho):h this

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7eha'ior &as :enerall! limited to 'er! hi:h or hea'il! loaded str)ct)res( si:nificantsettlement of the 7ac;fill sometimes res)lted in the same Boint clos)re6 It &as thereforenecessar! to select an alternati'e ad material6

The ne& ad is fa7ricated from an E/DM r)77er that is hi:hl! resistant to o>oneo3idation6 Most im ortant( it retains its resilienc! and does not crac;6 The ad desi:nconsists of a $* mm thic; solid la!er to ed 7! fo)r $* mm hi:h ri7s( for a total hei:ht of,* mm <.2% in=( Fi:)re 1616$ <there is also a ,1 mm <$ in= thic; ad )sed in &alls o'er #m <,* ft= hi:h=6 This desi:n demonstrates a t&o- hase stress-strain 7eha'ior6 Lo&loadin: rod)ces a relati'el! lar:e 'al)e of strain( corres ondin: in the field to aflattenin: of the ri7s6 As the load increases( corres ondin: to an increasin: hei:ht of

anels a7o'e the 7earin: ad ele'ation( the strain rate diminishes as the 7earin: load isdistri7)ted into the f)ll thic;ness of the ad6 Testin: indicates onl! $* to $1 thic;nessloss for ads at the 7ottom of a &all $*61 m <.%61 ft= hi:h6 This ad ro'ides the needed

7alance 7et&een com ressi7ilit! )nder increased load and the a7ilit! to maintain the

anel Boint in an o en condition6 For the fe& hi:her &alls or hi:her load-to-com ressionneeds( the ,1 mm <$ in= thic; ad ma! 7e )sed6

5&8 #ilter 4loth

How is bac$fill (re-ented from flowing through the 7oints between the facing (anels?

Reinforced Earth recast anels ha'e shi la ed:es and hori>ontal li s to allo& &ater todrain from the 7ac;fill and flo& do&n thro):h the anel Boints6 Mi:ration of 7ac;fill

fines into the Boints is re'ented 7! *61 m <$61 ft= &ide stri s of filter cloth :l)ed o'er the Boints on the 7ac; face of the &all <Fi:)re 16#6$=6 The filter cloth( s) lied 7! RECo( is anon-&o'en( needle )nched :eote3tile ha'in: the a ro riate h!sical ro erties tocontrol mi:ration of fines from the t! es of 7ac;fill t! icall! s ecified for ReinforcedEarth str)ct)res( &hile ermittin: draina:e to re'ent 7)ild) of h!drostatic ress)re6The filter cloth m)st ha'e the ro erties sho&n in Ta7le 16#6$ <ne3t a:e=6

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REFERENCES

$6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(

Di'ision II - Constr)ction( Section 06.6#6.6

,6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(

Di'ision I K Desi:n( Section $*6.,6

.6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16"616

%6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials $??# <Si3teenth Edition=( $??" Interim(

Di'ision I K Desi:n( Section 16"6#6$6$6

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.0 STA,ILITY

Sta7ilit! of Reinforced Earth str)ct)res is de endent ) on man! factors6 The n)m7er andlen:th of the reinforcin: stri s is determined 7! considerin: the com7ined effects of the

select and random 7ac;fills( the fo)ndation and 7ac;slo e materials( s)rchar:e loads(ser'ice life re )irements and( if a lica7le( s)7mer:ence conditions and seismicacceleration6 Constr)ction methods m)st also 7e considered( alon: &ith 7oth site ands)7soil draina:e and sco)r rotection6 Ultimatel!( sta7ilit! is ass)red 7! ro'idin: areinforced :ran)lar mass of s)fficient dimensions and str)ct)ral ca acit!( 7earin: onade )ate fo)ndation material( ha'in: a d)ra7le facin: material( &ell-chosen draina:es!stems( and ro er em7edment of the toe of the &all6

Reinforced Earth str)ct)res are e'al)ated for e ternal stabilit# and internal stabilit# 6E3ternal sta7ilit! considers the 7eha'ior of the site )nder the loadin: im osed 7! theReinforced Earth str)ct)re( and is rimaril! infl)enced 7! site :eotechnical and h!dra)lic

conditions6 Internal sta7ilit! refers to the 7eha'ior of and interrelationshi amon: thecom onents of the Reinforced Earth str)ct)re itself - the facin:( the reinforcin: stri s andthe select 7ac;fill6 Each t! e of sta7ilit! &ill 7e disc)ssed se aratel!6

8&' E)ternal Stabilit

A Reinforced Earth &all is a fle3i7le :ra'it! str)ct)re that resists slidin: and o'ert)rnin:d)e to its mass6 The slidin: and o'ert)rnin: calc)lations also consider the effect ofh!drostatic and seismic forces that are antici ated to 7e a lied d)rin: the life of the

str)ct)re6 Reinforced Earth &alls are :enerall! em7edded a minim)m de th 7elo&finished :rade( &ith the de th de endin: on the &all hei:ht and the slo e of the finished:rade in front of the &all6 Act)al em7edment ma! e3ceed the minim)m d)e to :rade'ariations alon: the &all face6

8&'&' Sliding and O-erturning

What are the assum(tions used in the sliding and o-erturning calculations?

Altho):h a Reinforced Earth str)ct)re is act)all! a fle3i7le mass( the slidin: ando'ert)rnin: calc)lations ass)me it 7eha'es as a ri:id 7od! <Reference $=6 This is areasona7le ass)m tion in the t! ical desi:n case &here the reinforcement len:th e )alsor e3ceeds a ro3imatel! 0* ercent of the &all hei:ht6 The hori>ontal forces andmoments d)e to 7oth the random 7ac;fill <7ehind the reinforced 'ol)me= and thes)rchar:e loads <a7o'e it= are calc)lated 7ased on the acti'e earth ress)re coefficient(H a( of the random 7ac;fill( &hile assi'e ress)re e3erted 7! the soil in front of the &all

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is ne:lected in the sta7ilit! calc)lations6 The coefficient of slidin: friction at the 7ase ofthe str)ct)re is the tan:ent of the friction an:le of either the Reinforced Earth 7ac;fill orthe fo)ndation material( &hiche'er is less6

What are the factors of safet against sliding and o-erturning?

A Reinforced Earth str)ct)re is dimensioned to ens)re sta7ilit! a:ainst slidin: ando'ert)rnin: 7! satisf!in: the factors of safet! ro'ided in Ta7le #6$6$6 Fi:)res #6$6$6$and #6$6$6, resent the e )ations for calc)latin: the factors of safet! a:ainst slidin: ando'ert)rnin: for Reinforced Earth str)ct)res &ith hori>ontal and slo in: 7ac;slo es(res ecti'el!6 If a 7rea; in the slo e 7ehind the &all facin: is located at a hori>ontaldistance from the &all face less than or e )al to t&ice the hei:ht of the &all( a 7ro;en

7ac; desi:n method is )sed <Fi:)re #6$6$6.=6

TA8LE #6$6$MINIMUM RE UIRED FACT4RS 4F SAFET9

Fail)re Mode Load Com7inationStatic 4nl! Static Seismic Static Dra&do&n

Slidin: $61 $6$ $6,4'ert)rnin: ,6* $61 $61

.1.2 E:+e/:e t

What is embedment? Wh do we (ro-ide embedment for Reinforced Earth structures?

The em7edment of a Reinforced Earth str)ct)re is defined as the distance from the 7aseof the Reinforced Earth mass <this is the ele'ation at the to of the le'elin: ad= to thefinished :rade in front of the &all6 Em7edment is re )ired to

• rotect a:ainst locali>ed erosion(

• maintain sta7ilit! at the toe of the &all( es eciall! if the finished :rade slo esa&a! from the &all( and

• ro'ide sco)r rotection for &alls alon: ri'ers and &aterfronts6

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What are the minimum embedment re/uirements recommended b RE4o?

The recommended minim)m em7edment for a Reinforced Earth str)ct)re 'ariesde endin: on str)ct)re t! e( hei:ht < =( and slo e in front of the str)ct)re <Reference ,=6The minim)m em7edment recommended 7! The Reinforced Earth Com an! ma! 7e

determined from Ta7le #6$6,6

TA8LE #6$6,

MINIMUM EM8EDMENT REC4MMENDATI4N

Str)ct)re T! e Slo e in Front of Wall Em7edment <Minim)m=JWalls and False ori>ontal 2,* <*6. m 2 $ ft=A7)tments <&ith iles= . $+ sl o e 2$, <*6%1 m 2 $61 ft=

, $+ slo e 20 <*6# m 2 ,6* ft=Tr)e a7)tments <no iles= ori>ontal 21 <*6? m 2 . ft=

J For a Reinforced Earth &all &ith finished :rade slo in: do&n and a&a! from the facin:(there sho)ld 7e a minim)m $ m <. ft= &ide le'el s)rface <7ench= 7et&een the &all face and the

7e:innin: of the slo e6 The minim)m em7edment re )ired for a Reinforced Earth tr)ea7)tment &ith a slo e in front is determined for each str)ct)re 7ased on a detailed :eotechnicale'al)ation6 For &alls constr)cted alon: 7odies of flo&in: &ater( fo)ndation ele'ation m)st 7ea minim)m of *6# m <, ft= 7elo& otential sco)r de th as determined 7! site-s ecific h!dra)licst)dies6

Is embedment below frost (enetration re/uired for a Reinforced Earth structure?

There are no ;no&n instances of dama:e to a Reinforced Earth str)ct)re d)e to frosthea'e6 This is 7eca)se

• the reinforced :ran)lar 7ac;fill is &ell drained and not s)sce ti7le to frost hea'e(

• the facin: anels are free to mo'e relati'e to each other( and

• the le'elin: ad is too narro& for si:nificant frost forces to de'elo in thefo)ndation soil6

There is no more threat of frost hea'e )nder a Reinforced Earth str)ct)re than there is)nder an ordinar! soil em7an;ment6

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8&. Internal Stabilit

Internal sta7ilit! desi:n of a Reinforced Earth str)ct)re consists of the determination ofsoil reinforcement t! e( si>e and )antit!6 Reinforced Earth str)ct)res are t! icall!

desi:ned )tili>in: standard reinforcin: stri s attached to recast concrete facin: anels&ith tie stri connections6 Th)s( the essence of the internal sta7ilit! desi:n rocess is thedetermination of the re )ired n)m7er <densit!= and len:ths of the reinforcin: stri s6

In s ecial cases( alternati'e soil reinforcement t! es ma! 7e )sed <see Section 16,6.=6 Ins)ch sit)ations( the t! e of soil reinforcement m)st 7e selected 7ased on roBect-s ecificconsiderations( 7)t the :eneral roced)re for internal sta7ilit! desi:n remains the same6

.2.1 Rei !orce:e t T5 e

What is the material and sha(e of the HA reinforcing stri(s and HA ladders?

Standard Reinforced Earth hi:h adherence reinforcin: stri s are fa7ricated of hot rolledsteel conformin: to the h!sical and mechanical ro erties of ASTM A-10, Grade #1 ore )i'alent6 The A stri s are 1* mm &ide 7! % mm thic;( &ith . mm hi:h ri7s oriented

er endic)lar to the lon: a3is and arran:ed in airs on 7oth the to and 7ottom of thestri ( as sho&n in Fi:)re #6,6$6$6 After fa7rication( the reinforcin: stri s are hot di:al'ani>ed in accordance &ith ASTM A-$,.( &hich ro'ides a minim)m of *6#$ ;:2s m<,6* o>2s ft= of >inc <*6"#µm minim)m thic;ness la!er=6

A ladders are fa7ricated from cold dra&n steel &ire conformin: to ASTM A-", Grade#16 The ladders consist of t&o lon:it)dinal 7ars s aced 1* mm <, in= on center &ith $**mm <% in= lon: trans'erse 7ars s aced $1* mm <# in= on center6 The trans'erse 7ars are&elded in accordance &ith ASTM A-$"16 Li;e the A stri s( the A ladders are hot di:al'ani>ed accordin: to ASTM A-$,. <*6#$ ;:2s m ,6* o>2s ftO of >inc=6

How do the ribs on the HA reinforcing stri( 9cross bars on the HA ladder: enhance thesoil*reinforcement interaction?

The hi:h adherence reinforcin: stri <ladder= is an efficient soil load transfer de'ice 7eca)se the soil articles are com acted 7et&een and a:ainst the faces of the ri7s<trans'erse 7ars=6 ori>ontal soil stresses are transferred to the steel 7! direct 7earin: ofsoil a:ainst the ri7 <7ar= faces( and mo'ement of the stri <ladder= is resisted 7! soil-to-soil friction across the to s of the ri7s <7et&een and across the 7ars=( rather than sim l!

7! soil-to-steel friction alon: the s)rfaces of the stri <ladder=6 In addition( soil dilatanc!

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leads to apparent friction ( fJ( that is :reater than the soil shear stren:th <fJ V tan φ=6 Theim ortance of the ri7s <7ars= can 7e seen 7! com arin: the t&o coefficients of friction fora t! ical Reinforced Earth 7ac;fill ha'in: an internal friction an:le φ .%°

• For lane friction 7ased onl! on soil shear stren:th( fJ tan φ *6#016

• For A stri s < A ladders=( fJ ,6* at the to of the str)ct)re( decreasin:linearl! to tan φ at a de th of #6* m <,* ft= and remainin: constant at tan φ forde ths :reater than #6* m6

This means that( d)e to dilatanc! and fJ( more frictional stren:th is a'aila7le in the ) er art of the str)ct)re e'en tho):h there is less confinin: ress)re6 Therefore( it is notnecessar! to ha'e more reinforcements near the to of the anel to com ensate for thelo&er confinin: ress)re6 In addition( since the A ladder is t&ice as &ide as the Astri ( it offers t&ice the )llo)t resistance and is more efficient near the to of the &all&here )llo)t controls the desi:n6

.2.2 Rei !orce:e t Le -t#

What is the length of the reinforcing stri(s? How is it determined?

The first ste in determinin: reinforcement len:th is to satisf! the re )irements fore3ternal sta7ilit! <slidin: and o'ert)rnin:( see Section #6$=6 In :eneral( the reinforcementlen:th res)ltin: from the e3ternal sta7ilit! anal!sis &ill ro'e to 7e the minim)mreinforcement len:th for the str)ct)re6 Satisf!in: internal sta7ilit! re )irements is the

ne3t ste 6

For internal sta7ilit!( the soil reinforcement len:th m)st 7e s)fficient to ro'ide theminim)m re )ired factor of safet! a:ainst )llo)t6 AAS T4 <Reference .= re )ires thatthe len:th of reinforcin: stri s for Reinforced Earth str)ct)res 7e at least 0* ercent ofthe &all hei:ht( &ith a minim)m len:th of ,6% m <" ft=6 These limits are rimaril! toens)re a sta7le ratio of 7ase &idth to &all hei:ht( there7! 'alidatin: the :ra'it! sta7ilit!calc)lation ass)m tions( and to satisf! constr)cti7ilit! considerations6

The ri77ed s)rfaces of the reinforcin: stri ro'ide an adherence characteristic :reaterthan that of a smooth stri <as disc)ssed a7o'e in Section #6,6$=6 E3tensi'e testin: of

Reinforced Earth hi:h adherence reinforcin: stri s sho&s that the adherence can 7eacc)ratel! estimated 7! the frictional arameter ;no&n as the a arent coefficient offriction( fJ <Reference %=6 The 'al)e of fJ 'aries 7! soil t! e and o'er7)rden ress)re(and AAS T4 <Reference 1= s ecifies a ma3im)m fJ 'al)e of ,6* at the :ro)nd s)rface(decreasin: linearl! to tan φ at a de th of # m <,* ft= and remainin: constant at tan φ for

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:reater de ths6 Since hi:h adherence stri s e3hi7it :reater a arent friction in &ell:raded soils than in fine sands( the fJ 'al)e )sed for desi:n of an! roBect m)st 7ederi'ed from the t! e of 7ac;fill material to 7e )sed <or s ecified= for that roBect6

For internal sta7ilit! desi:n( the n)m7er and len:th of the reinforcements m)st 7e

s)fficient to ro'ide an ade )ate factor of safet! a:ainst )llo)t at e'er! reinforcementle'el6 Testin: of Reinforced Earth str)ct)res sho&s that a fail)re lane de'elo s &ithinthe reinforced mass( di'idin: the mass into an acti'e >one and a resisti'e >one <Fi:)re#6,6,6$=6 The acti'e >one is &here earth ress)re is mo7ili>ed and its force transferred tothe reinforcements thro):h friction <si:nificant earth ress)re is also a lied to the facin:

anels=6 The resisti'e >one is &here the soil2stri adherence characteristics are mo7ili>edto resist )llo)t of the stri s6 The len:th of the stri &ithin the resisti'e >one is called theeffective length 6

Earth ress)re on the 7ac; of a Reinforced Earth str)ct)re <at the 7ac; of the reinforcedsoil mass= is calc)lated 7! the Ran;ine method6 The effect of a li'e load traffic s)rchar:e

on the calc)lation of stri )llo)t factor of safet! is determined as sho&n in Fi:)re#6$6$6$( &hile earth ress)re for slo in: s)rchar:es is determined as sho&n in Fi:)res#6$6$6, and #6$6$6.6 At each le'el of soil reinforcement( the 'ertical stress is determined

7! e'al)atin: all forces actin: at and a7o'e that le'el6 The s)mmation of forces isconsidered to 7e distri7)ted )niforml! o'er an effecti'e &idth 8 L K ,e( as defined inAAS T4 <Reference #= and sho&n in Fi:)re #6,6,6,6 The hori>ontal stress is thendetermined 7! m)lti l!in: the 'ertical stress 7! an earth ress)re coefficient( H<Reference 0=6 The earth ress)re coefficient is H H o <at-rest ress)re= at the to of thestr)ct)re( decreasin: linearl! to H H a <acti'e ress)re= at a de th of # m <,* ft=6 Hremains constant and e )al to H a 7elo& # m <ri:ht side of Fi:)re #6,6,6$=6

Resisti'e forces are de'elo ed alon: the effecti'e len:th of the stri and are calc)lated asthe rod)ct of the a arent coefficient of friction( fJ( the o'er7)rden soil ress)re and thes)rface area of stri in the resisti'e >one <Reference 1=6 The factor of safet! a:ainst stri

)llo)t at each le'el is calc)lated 7! the e )ation

FSf S A N

S A )llo)t' s

h

=

J

&here

fJ a arent coefficient of friction

S ' 'ertical stress d)e to o'er7)rden soil a7o'e stri <)nit &ei:ht 3 fill hei:ht=A s s)rface area of a reinforcin: stri &ithin the resisti'e >one

N n)m7er of reinforcin: stri s er tri7)tar! &all areaSh hori>ontal earth ress)re at le'elA tri7)tar! &all area6

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.2.3 S aci - o! Rei !orce:e t

How man stri(s are there in a wall?

For internal sta7ilit! considerations( the c)m)lati'e cross sectional area of the steelreinforcin: stri s m)st 7e s)fficient to carr! the soil loads6 After s)7tractin: thethic;ness of steel &hich &ill 7e sacrificed to corrosion d)rin: the life of the str)ct)re( thereinforcement cross sectional area re aining at the end of the service life is desi:ned to

7e :reater than that re )ired to carr! the allo&a7le tensile stress( *611F ! <Reference "=6

As disc)ssed in the re'io)s section( the earth ress)re on the 7ac; of a Reinforced Earthstr)ct)re is determined 7! the Ran;ine method6 For the stri stress calc)lation( the effectof an! li'e load s)rchar:e is determined as sho&n in Fi:)re #6$6$6$( &hile the earth

ress)re for slo in: s)rchar:es is determined in accordance &ith Fi:)res #6$6$6, and#6$6$6.6

The roced)re for determinin: earth ress)res at each le'el of reinforcement &ithin thestr)ct)re is the same as the roced)re o)tlined for reinforcin: stri )llo)t safet! inSection #6,6,( e3ce t that the li'e load s)rchar:e is a lied directl! o'er the reinforced>one6 This res)lts in hi:her 'ertical and hori>ontal stresses &ithin the Reinforced Earthstr)ct)re and( therefore( hi:her stresses in the reinforcement6 The res)lt is a moreconser'ati'e reinforcement desi:n6

How is the number of stri(s (er (anel determined?

4nce the hori>ontal stress transfer at a reinforcement le'el is determined( the n)m7er ofstri s re )ired at that le'el is calc)lated 7! the follo&in: e )ation

NS A

A Fh

s !

=

< =

< 6 =* 11

&here

N n)m7er of stri s er tri7)tar! &all area <ro)nded ) to the nearest inte:er=Sh hori>ontal earth ress)re at that le'elA tri7)tar! &all areaA s cross sectional area of reinforcin: stri <at end of ser'ice life=F! !ield stren:th of steel reinforcin: stri s6

The tri7)tar! &all area )sed in the calc)lation a7o'e is t! icall! ,6,1 s m <,%6, s ft= forReinforced Earth str)ct)res )sin: standard cr)ciform anels6 This corres onds to half a

anel hi:h <*601 m ,6%# ftO=( 7! t&o anels &ide <.6* m ?6"% ftO=6 The n)m7er of stri s

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re )ired er tri7)tar! area is then ro'ided across that anel area6 Th)s( as sho&n inFi:)re #6,6.6$( a re )ired n)m7er of stri s N 1 res)lts in anels A1 and 8, across the

7ottom of a Reinforced Earth str)ct)re6 The three 7ottom-most reinforcin: stri s of theA1( alon: &ith the t&o reinforcin: stri s of the 8,( total 1 stri s for the ,6,1 s mtri7)tar! area <the shaded area in Fi:)re #6,6.6$=6 For other anel t! es( the n)m7er of

stri s ro'ided er anel is determined as the ratio of the act)al anel area to the ,6,1s m tri7)tar! area6

First consideration is al&a!s :i'en to the )se of standard recast facin: anels and theefficient )se of steel stri s &hen desi:nin: a Reinforced Earth str)ct)re6 The selection oftri7)tar! &all area to 7e )sed for desi:n and the determination of the distri7)tion of stri sattached to the anels ma3imi>es the efficienc! of the s!stem6 The Reinforced Earthdesi:n methodolo:! ro'ides for the )niform distri7)tion of soil reinforcementsthro):ho)t the reinforced mass( the o timal )se of steel reinforcin: stri s( and the )se ofstandard facin: anels6

8&2 O-erall 9;lobal: Stabilit

What is the difference between e)ternal stabilit and o-erall stabilit ?What is the definition of 1slo(e stabilit 1 with res(ect to o-erall stabilit of a

Reinforced Earth structure?

As &as disc)ssed re'io)sl! <Section #6$=( consideration of the e3ternal sta7ilit! of aReinforced Earth str)ct)re is reall! consideration of the interaction 7et&een theReinforced Earth 'ol)me and the fo)ndation soils and random 7ac;fill6 S ecificall!( thee3ternal sta7ilit! calc)lations determine the factors of safet! for slidin: and o'ert)rnin:<Fi:)re #6.6$( arts aO and 7O( res ecti'el!=6 A chec; of overall sta7ilit!( on the otherhand( loo;s not onl! at the Reinforced Earth 'ol)me and its relationshi to the adBacentsoils( 7)t also at the characteristics of the dee er strata that &ill affect the sta7ilit! of the&hole str)ct)re( em7an;ment and2or hillside <Fi:)re #6.6$( art cO=6 De endin: on thes ecific site conditions( a :lo7al fail)re lane or sli circle mi:ht ass com letel! o)tsideof the reinforced >one6 Since it is eas! to ro'ide s)fficient reinforcin: stri s to re'entmo7ili>ation of a fail)re lane or sli circle that does ass thro):h the reinforced soilmass( the resence of the Reinforced Earth str)ct)re ma! act)all! im ro'e :lo7alsta7ilit! of the entire em7an;ment <Fi:)re #6.6,=6

What is the definition of 1#actor of Safet 1 with res(ect to a global stabilit anal sis?

In a sta7le slo e( onl! a ortion of the total a'aila7le resistance alon: a otential shear<sli = s)rface &ill 7e re )ired to 7alance the dri'in: force6 Therefore( the factor of safet#a:ainst shear fail)re is sim l! the ratio6

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ForceDri'in:ResistanceShearA'aila7le

= *+

In desi:nin: for :lo7al sta7ilit!( it is c)stomar! to ha'e a redetermined acce tance 'al)efor the factor of safet! and to adB)st the desi:n )ntil the factor of safet! calc)lated for thedesi:n e )als or e3ceeds the redetermined 'al)e6 A 'al)e of $6. is c)stomar! for most

a lications( 7)t a 'al)e of $61 ma! 7e re )ired for a lications s)ch as 7rid:e a7)tmentsor str)ct)res s) ortin: rail&a!s <critical str)ct)res=6

What are the methods to determine the #actor of Safet against a global failure?

8isho s Modified Method of Slices is the most &idel! )sed method for determinin: the:lo7al factor of safet! alon: a otential sli circle6 In s ecial cases( s)ch as &hen there isan inclined fa)lt la!er or a &ea; >one 7eneath the Reinforced Earth 'ol)me( a non-circ)lar anal!sis ma! 7e re )ired to in'esti:ate other ossi7le fail)re modes6 RECo )sesa modified 'ersion of the com )ter ro:ram STA8L to erform :lo7al sta7ilit! anal!sis6

Usin: this ro:ram( a non-circ)lar anal!sis can 7e erformed and sta7ilit! res)ltin: fromthe tensile and adherence ro erties of the reinforcements can 7e ta;en into acco)nt6

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REFERENCES

$6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16"6,6

,6 Technical 8)lletin MSE-0( Minim)m Em7edment Re )irements for MSE Str)ct)res (The Reinforced Earth Com an!( $??16


Di'ision I - Desi:n( Section 16"6$6

%6 Technical 8)lletin MSE-#( A arent Coefficient of Friction( fJ( to 7e Used in theDesi:n of Reinforced Earth Str)ct)res( The Reinforced Earth Com an!( $??1

16 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(Di'ision I - Desi:n( Section 16"61 and Fi:)re 16"616,A6

#6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16"6.6

06 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16"6%6$ and Fi:)re 16"6%6$C6

"6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( $??" Interim(

Di'ision I - Desi:n( Section 16"6#6$6

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.0 FOUNDATION CONSIDERATIONS

This section disc)sses Reinforced Earth str)ct)re fo)ndation iss)es ertainin: to 7earin:ca acit!( settlement and differential settlement6 The 7earin: ca acit! of tr)e a7)tments is

disc)ssed in a se arate s)7section <Section 06,= to em hasi>e its im ortance and the needfor roBect-s ecific desi:n information on this to ic6

<&' 6earing 4a(acit of the #oundation Soil

What is the difference between a((lied bearing (ressure and allowable bearing (ressure?

The a lied 7earin: ress)re is the ress)re e3erted on the fo)ndation soil 7! a str)ct)res)ch as a Reinforced Earth &all6 For a t! ical Reinforced Earth str)ct)re not ha'in: a

sloping s)rchar:e( the a lied 7earin: ress)re can 7e appro i ated as $.1 of thecom7ined dead &ei:ht of the reinforced 'ol)me and the s)rchar:e <Reference $=6 Theallo&a7le 7earin: ress)re( on the other hand( is the 'al)e o7tained 7! a l!in: a factorof safet! to the )ltimate 7earin: ca acit! of the fo)ndation soil( &here the )ltimate

7earin: ca acit! has 7een calc)lated )sin: the Ter>a:hi 7earin: ca acit! e )ation<Reference ,= or 7! a similar method6 8earin: ca acit! rimaril! de ends on the shearstren:th of the fo)ndation soil( the em7edment de th of the str)ct)re( and the effect ofs)7mer:ed conditions( if resent6 Desi:nin: a Reinforced Earth str)ct)re 7ased on a

ro erl! determined )ltimate 7earin: ca acit!( &ith a factor of safet! a lied( is the referred desi:n method to a'oid fo)ndation shear fail)re6

How can bearing ca(acit theories be a((lied to a Reinforced Earth Structure? Arethere differences in the method of a((lication?

8earin: ca acit! theories are 7est a lied to ri:id str)ct)res6 For semi-fle3i7le str)ct)ress)ch as those constr)cted of Reinforced Earth( one m)st )se en:ineerin: B)d:ment ininter retin: the res)lts of the 7earin: ca acit! e )ation( since the str)ct)re s fle3i7ilit!

7oth ermits and B)stifies a hi:her allo&a7le 7earin: ress)re than the calc)lationss)::est6

8ased on the 7earin: ress)re distri7)tion )nder the reinforced 'ol)me( an e )i'alentfootin: &idth can 7e assi:ned to the str)ct)re6 As ill)strated in Fi:)re 06$6$( Me!erhofhas sho&n that this footin: &idth is e )al to the reinforcement len:th min)s t&o timesthe eccentricit! of the str)ct)re6 For a cohesionless 7earin: soil( this &idth is )sed in thedetermination of the )ltimate 7earin: ca acit! )sin: con'entional 7earin: ca acit!theor!6 In the case of cohesi'e 7earin: soil( the &idth of the footin: la!s a lesser role indeterminin: the 7earin: ca acit!6

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D)e to the )ncertainties inherent in an! calc)lation of soil stren:th <since soil ro ertiescan 'ar! si:nificantl! e'en a fe& meters a&a! from &here a sam le &as ta;en=( theallo&a7le 7earin: ress)re for footin:s s) ortin: ri:id str)ct)res is commonl!determined 7! a l!in: a factor of safet! of .6* to the )ltimate 7earin: ca acit!6 Thecom arati'e fle3i7ilit! of a Reinforced Earth str)ct)re( ho&e'er( B)stifies the )se of a

lo&er factor of safet! a:ainst 7earin: fail)re <Reference $( Reference .=( as follo&s• a factor of safet! of ,6* for roBects &ith detailed :eotechnical information( and

• a factor of safet! ,61 for roBects &ith :eneral :eotechnical information6

4an longer reinforcements be used to reduce the bearing (ressure?

When ins)fficient 7earin: ca acit! is a'aila7le( 4&ners and Cons)ltants sometimes as;a7o)t )sin: lon:er reinforcements in an effort to red)ce the a lied 7earin: ress)re)nder the str)ct)re6 Since the 7earin: ress)re calc)lation de ends( in art( on the 7ase&idth of the str)ct)re( the! reason that lon:er reinforcements <a lar:er 7ase &idth= &illred)ce the calc)lated 7earin: ress)re6 The relationshi 7et&een the Reinforced Earth'ol)me and retained lateral loads( ho&e'er( res)lts in eccentricit! <Fi:)re 06$6,= thatre )ires the 7earin: &idth <introd)ced in Section #6,6,= to 7e calc)lated as follo&s

8 L K ,e

&here

8 E )i'alent 8earin: Width e Eccentricit! <Fi:)re 06$6$=L Reinforcement Len:th Wall ei:ht

As the reinforcement len:th <L= increases( there is a decrease in eccentricit! <e=( s)ch that 7earin: ress)re &idth <8= a roaches L6 The res)ltin: 7earin: ress)re( therefore(cannot 7e red)ced to less than the load of the soil mass( irres ecti'e of the reinforcementlen:th <see fi:)re 06$6,=6

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<&. =rue Abutment 6earing 4a(acit

What is a 1true abutment?1 What is the allowable bearing (ressure?

A tr)e a7)tment is a Reinforced Earth str)ct)re &ith a 7rid:e a7)tment s read footin: 7earin: directl! on to of the reinforced soil <Fi:)re 06,6$=6 The footin: 7ears onl# on thereinforced soil and is not s) orted 7! iles or other str)ct)ral mem7ers6 A7)tment

7earin: ress)re is transferred directl! into the reinforced soil and( de endin: on thehei:ht of the Reinforced Earth str)ct)re( either is f)ll! dissi ated &ithin the reinforcedsoil or is distri7)ted thro):h it to the site fo)ndation soil 7elo&6

The follo&in: m)st 7e considered &hen desi:nin: a Reinforced Earth tr)e a7)tment

• The 7earin: ca acit! of the site fo)ndation soil( as disc)ssed in Section 06$6

• The allo&a7le 7earin: ress)re of the 7eam seat ato the Reinforced Earth select 7ac;fill6 The allo&a7le 7earin: ress)re is set at $?* ;/a <%*** sf=( consistent&ith :ood en:ineerin: ractice for footin:s on com acted :ran)lar fill6

The ress)re )nder the a7)tment footin: is dissi ated &ith de th thro):h the ReinforcedEarth 'ol)me accordin: to the 8o)ssines ress)re distri7)tion <Reference ,=6 Forcom )tational sim licit!( and 7eca)se it is conser'ati'e <it en'elo es the 8o)ssinesdistri7)tion=( a $ , < ori>ontal to +ertical= linear ress)re distri7)tion is )sed instead<Fi:)re 06,6,=6 In order to limit the ress)re a lied directl! to the &all facin: anels( thea7)tment s centerline of 7earin: m)st 7e at least $ m <. ft= 7ehind the facin:6 Where the$ , distri7)tion intersects the face of the Reinforced Earth &all( the load from thea7)tment is transferred thro):h the reinforcin: stri s 7ac; to the reinforced soil mass ashori>ontal stress6 This increased hori>ontal stress in a Reinforced Earth tr)e a7)tmentma! re )ire additional reinforcin: stri s as com ared to a retainin: &all desi:n6

What is the affect of the abutment footing on the a((lied bearing (ressure beneath the Reinforced Earth structure?

When the Reinforced Earth &all hei:ht e3ceeds three times the &idth of the a7)tmentfootin:( the 7earin: ress)re from the a7)tment is almost com letel! dissi ated &ithinthe Reinforced Earth 'ol)me accordin: to the $ , ress)re distri7)tion disc)ssed a7o'e6

Therefore( the fo)ndation soil does not recei'e si:nificant additional 7earin: ress)re d)eto the resence of the a7)tment6 This is an im ortant ad'anta:e in the case of mar:inalfo)ndation soils that can acce t the distri7)ted load of a Reinforced Earth &all 7)t not theadditional concentrated load of an a7)tment footin:6 This 7earin: ress)re ad'anta:eoffered 7! a Reinforced Earth a7)tment ma! allo& the a7)tment to 7e 7)ilt &itho)t iles6

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For a7)tment &alls of lesser hei:ht <those less than t&ice as hi:h as the a7)tment footin:is &ide=( the total 7earin: ress)re at the fo)ndation &ill 7e the s)m of the )ndissi ated

ortion of the $ , ress)re distri7)tion <the ortion &hich e3tends 7elo& the 7ase of thereinforced 'ol)me= and the 7earin: ress)re determined 7! con'entional ReinforcedEarth desi:n calc)lations6 Therefore( the allo&a7le 7earin: ress)re for the site m)st 7e

s)fficient to s) ort this increased load6

<&2 =otal Settlement

What is the 1total settlement1 of a Reinforced Earth structure and what beha-iorcontributes to this settlement?

The total settlement of a Reinforced Earth str)ct)re is the s)m of

• the settlement of the fo)ndation soil d)e to o'er7)rden ress)re <in this case theReinforced Earth str)ct)re is the o'er7)rden=( and

• the internal com ression of the reinforced fill d)e to the com action effort )sedand the 'ertical forces a lied to the str)ct)re6

D)e to the interaction 7et&een the reinforcin: stri s and the select 7ac;fill( the internal 7eha'ior of a Reinforced Earth str)ct)re is different from that of an )nreinforcedem7an;ment of the same 7ac;fill material6 As la!er after la!er is added to a ReinforcedEarth str)ct)re( the reinforced 'ol)me 7eha'es as a 7loc; and the reinforcements re'ent

ost-com action lateral strain and the res)ltin: shortenin: of the str)ct)re in the 'erticaldirection <internal settlement=6 Therefore( the internal settlement of a Reinforced Earthstr)ct)re is limited to the ne:li:i7le com ression of the select 7ac;fill6 4n the otherhand( settlement of the fo)ndation <in-sit)= soil ca)sed 7! constr)ction of a ReinforcedEarth str)ct)re ma! 7e estimated )sin: classical soil mechanics theor!6

Since the settlement of a Reinforced Earth str)ct)re d)rin: constr)ction is adB)sted forincrementall! in the &all constr)ction rocess( the str)ct)re s allo&a7le ost-constr)ctionsettlement is t! icall! limited onl! 7! the deforma7ilit! of the facin:6 In some cases(

ost-constr)ction settlement ma! also affect str)ct)res adBacent to or s) orted 7! theReinforced Earth mass( s)ch as tr)e 7rid:e a7)tments or maBor si:n str)ct)res6 If ost-constr)ction settlement is antici ated to e3ceed 01 mm <. in=( an a ro riate &aitin:

eriod <t! icall! at least , months= ma! 7e recommended 7efore installin: the adBacent ors) orted str)ct)re and 7efore adB)stin: the final desi:n ele'ations alon: the to of theReinforced Earth facin:6 Settlement e3 ected to 7e in e3cess of .** mm <$, in= ma!re )ire a &aitin: eriod too lon: for the roBect timeline( in &hich case t&o-sta:econstr)ction or fo)ndation sta7ili>ation techni )es sho)ld 7e in'esti:ated6

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What is the tolerable total settlement for a Reinforced Earth structure?

There is no formal definition of the tolera7le total settlement for a Reinforced Earthstr)ct)re6 Some Reinforced Earth &alls ha'e e3 erienced as m)ch as *6# m <, ft= of totalsettlement6 While this ight 7e acce ta7le for a retainin: &all not ha'in: a road&a! or

other ele'ation-sensiti'e str)ct)re on to ( it &o)ld 7e totall# $nacceptable for ana7)tment or a &all connectin: to another str)ct)re <)nless the settlement co)ld 7ecom ensated for in some manner=6 In :eneral( settlement is not m)ch of a concern if it isnot accom anied 7! an )nacce ta7le amo)nt of differential settlement <see Section 06%=(since it is e3cessi'e differential settlement that can lead to &all dama:e6

What are the effects of 1immediate settlement1 and 1consolidation settlement1 on Reinforced Earth structures?

Immediate settlement is settlement that occ)rs <and ends= d)rin: or 'er! soon after &allconstr)ction( )s)all! &ithin the time d)rin: &hich the o'erall roBect is still )nderconstr)ction6 This timin: often ermits the &all com onents( the roBect :radin:( or 7othto 7e adB)sted to ma;e ) for the ele'ation PlostP d)e to settlement( allo&in: the roBectto 7e com leted to the ori:inall! s ecified :rades6 If it occ)rs )niforml! )nder the &holestr)ct)re and is ro erl! corrected( immediate settlement sho)ld ha'e no effect on thelon:-term 7eha'ior or erformance of a Reinforced Earth str)ct)re6

Consolidation settlement( on the other hand( is lon:-term settlement d)e to consolidationof the fo)ndation soils )nder the load im osed 7! the Reinforced Earth mass <and 7!other roBect com onents=6 Consolidation settlement can :o on for months or e'en !ears(

7)t the rate of settlement :enerall! decreases &ith time6 For this reason( a :eotechnicalre ort that redicts consolidation settlement sho)ld incl)de an estimate of T ?*( the timefor ?* of the e3 ected settlement to occ)r6 The roBect 4&ner sho)ld )nderstand that(ideall!( remedial meas)res to com ensate for this settlement sho)ld not 7e attem ted atleast )ntil T ?* has 7een reached( altho):h earlier remediation ma! 7e acce ta7le orre )ired de endin: on roBect conditions6

Note that immediate and consolidation settlement are not necessaril# har f$l to thestr)ct)ral inte:rit! and erformance of a Reinforced Earth &all( as lon: as the! occ)re'enl! )nder the &hole str)ct)re6 If the ma:nit)de of settlement 'aries alon: the len:thof a &all( ho&e'er( this differential settlement co)ld( )nder certain circ)mstances( ose a

ro7lem6 This iss)e is addressed f)ll! in Section 06%6

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<&% Differential Settlement

What is the definition of 1differential1 settlement?

Differential settlement is the difference 7et&een the amo)nts of settlement o7ser'ed att&o different oints on a str)ct)re( e3 ressed as a ercenta:e of the distance se aratin:those oints <Fi:)re 06%6$=6 For e3am le( if the! are se arated 7! $** m and one ointsettles $ m more than the other does( then the differential settlement is $ 6 Differentialsettlement is al&a!s determined relative to the initial and final positions of the two

points ( so if one oint settles $ m and the other settles , m( the differential settlement isstill $ m < $ if the! are $** m a art as in the e3am le a7o'e=6 The t&o oints do notha'e to 7e at the same ele'ation initiall! in order to calc)late differential settlement6

What is the tolerable differential settlement for a Reinforced earth structure?

The erformance of a Reinforced Earth str)ct)re d)rin: settlement de ends rimaril! onthe characteristics of its facin: s!stem6 A Reinforced Earth &all constr)cted of recastconcrete anels can tolerate ) to $ differential settlement &itho)t an! distress( so theeffect of 'ar!in: fo)ndation soil ro erties is rarel! a ro7lem <Reference $=6 o&e'er(if the :eotechnical in'esti:ation s)::ests that :reater than $ differential settlement ma!occ)r( sli Boints <Section ?6$= ma! 7e )sed( t#picall# located e'er! $*-,* anels <$1-.*m 1*-$** ftO= alon: the &all6 In the case of a 'er! hi:h &all( tiers <Section ?6$.= ma! 7e)sed to rod)ce a stac; of , or more &alls( each of lesser hei:ht and set 7ac; 7ehind theone 7elo&( red)cin: the effect of settlement on each &all as com ared to the effect on asin:le &all of the com7ined hei:ht6

What are the causes of differential settlement?

There are fo)r rinci al ca)ses of differential settlement of Reinforced Earth &alls

• Si:nificant 'ariation in the stren:th characteristics of the fo)ndation soils alon: thelen:th of the &all(

• A s)dden chan:e in &all hei:ht or str)ct)re :eometr! s)ch that there is a s)ddenchan:e in the load im osed on the fo)ndation(

• The resence of a lar:e( ri:id str)ct)re adBacent to the Reinforced Earth &all( and

• An ac)te corner )na'oida7l! located &here fo)ndation soils are less com etent<altho):h an ac)te corner ma! 7e li:hter than the adBacent PnormalP &all( 7earin:

ress)re is more concentrated( leadin: to increased 7earin: stress=6 See alsoSections ?6. and ?6$.6

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<&5 #oundation Stabilization !ethods

In marginal soil conditions+ how can bearing ca(acit be im(ro-ed and how can totaland0or differential settlement be minimized?

In some cases( the 7earin: soils located 7eneath lanned Reinforced Earth str)ct)res arein s)ch a mar:inal state that im ro'ement is necessar! to ro'ide ade )ate 7earin:ca acit! and2or to red)ce 7oth immediate and consolidation settlement <see Sections 06.and 06% for disc)ssions of settlement=6 Se'eral fo)ndation soil im ro'ement methods thatha'e 7een s)ccessf)ll! )sed to increase 7earin: ca acit! and red)ce lar:e-scalesettlements 7eneath Reinforced Earth str)ct)res are disc)ssed 7elo&6

• Underc)t and Re lace 6 The sim lest <and most fre )entl! )sed= method is to)nderc)t the &ea; soil and re lace it &ith select :ran)lar material <Fi:)re 0616$=6 Ifthe re )ired de th of )nderc)t e3ceeds , - ,61 m <#61 - " ft= or if :ro)nd&ater isnear the s)rface( ho&e'er( )nderc)ttin: ma! 7e im ractical and2or )neconomical6

• /reloadin:6 Traditionall!( reloadin: is the constr)ction of a tem orar!em7an;ment for the )r ose of forcin: 7oth immediate and <at least some=consolidation settlement of the fo)ndation soil rior to erection of the finalstr)ct)re <Fi:)re 0616,=6 Where a ro riate( de endin: on the rate and amo)nt ofsettlement e3 ected( a artic)larl! time- and cost-efficient 'ersion of reloadin: iserection of the Reinforced Earth str)ct)re in sta:es( allo&in: it to act as the reloads)rchar:e6 This method ro'ides o ort)nities to modif! the str)ct)re desi:n ifneeded as settlement occ)rs6

• A 'ariation of the P7)ild-the-&all-in-sta:esP techni )e is the sta:ed constr)ction ofa ,erratrel ® &ire-faced Reinforced Earth str)ct)re6 Terratrel s &ire facin: has farmore fle3i7ilit! and differential settlement tolerance than does a recast facin:( sothe Terratrel &all can accommodate si:nificant ost-constr)ction settlement6/recast anels or a cast-in- lace facin: can 7e erected after settlement has sto ed6

• Clearl!( a caref)l :eotechnical e'al)ation sho)ld accom an! an! reloadin:scheme to re'ent o'erloadin: and shearin: of the 7earin: soils6 In addition(installation of ⁣ drains d)rin: reloadin: can 7e considered to f)rther increasethe rate of settlement 7! dissi atin: ore &ater &ithin the 7earin: soils6

•

• Fo)ndation Sta7ili>ation 6 Soil sta7ili>ation meas)res ma! 7e )sed to create as)rface la!er of select( reinforced soil 7elo& the Reinforced Earth str)ct)re6 Thesta7ili>ation la!er can 7e created either <a= 7! installin: o'er the mar:inal soils a$ - $61 m <. K #61 ft= thic; la!er of select :ran)lar fill reinforced 7! se'eral la!ersof :eos!nthetic or steel stri reinforcement or <7= 7! erformin: in-sit) soil cementmi3in: in the ) er $ - $61 m of the mar:inal soil la!er <Fi:)re 0616.=6

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• Controlled Mod)l)s Col)mns <CMC= or D!namic Re lacement Col)mns6 Thesetechnolo:ies are a'aila7le from Menard LLC( Soil Im ro'ement S ecialists( a&holl! o&ned s)7sidiar! of The Reinforced Earth Com an!6 More information onMenard technolo:ies can 7e o7tained thro):h an! RECo office6

• Col)mn Incl)sions 6 Stone col)mns( Bet :ro)ted col)mns( 'i7ro-re lacementcol)mns( and other incl)sion installations ha'e 7een )sed to transfer loads fromReinforced Earth str)ct)res thro):h mar:inal ) er soils and into a dee er( moresta7le soil or 7edroc; la!er6 Added 7enefits of col)mn incl)sions ma! incl)deim ro'ements to 7ase lateral sta7ilit! and red)ced &aitin: time com ared to

reloadin: schemes <Fi:)re 0616%=6

• /roBect Modifications 6 Altho):h the! are not s ecificall! fo)ndation sta7ili>ationmeas)res( there are certain modifications to the roBect :eometr! or to theReinforced Earth materials that ma! hel ro'ide a sta7le str)ct)re6 4ne s)chmodification is the lacement of a 7erm in front of the Reinforced Earth mass to

create a co)nter&ei:ht to resist ossi7le sli s)rface mo'ement <Fi:)re 06161a=6Another is the )se of li:ht&ei:ht fill materials( s)ch as nat)ral or rocessed lo&densit! a::re:ate( to red)ce the load transferred from the Reinforced Earthstr)ct)re to the fo)ndation soil <Fi:)re 061617=6

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REFERENCES

$6 S)7s)rface In'esti:ation and Im ro'ements for MSE Str)ct)res Constr)cted on /oorFo)ndation Soils( The Reinforced Earth Com an!( )ndated6

,6 Soil Mechanics and En:ineerin: /ractice ( Second Edition( Harl Ter>a:hi and Ral h86 /ec;( @ohn Wile! Sons( $?#06


Di'ision I - Desi:n( Section 16"6.6

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.0 @ALL CONSTRUCTION DRA@INGS AND GENERALDETAILS

The Reinforced Earth Com an! <RECo= ro'ides 4&ners &ith t&o t! es of dra&in: setsfor a ro'al and )se d)rin: constr)ction

• Wall Constr)ction Dra&in:s <sometimes called PSho Dra&in:sP= and

• /anel Castin: Dra&in:s6

This section descri7es the &all constr)ction dra&in:s and identifies the informationneeded 7! RECo to rod)ce them6

For com leteness and clarit!( Reinforced Earth dra&in:s t! icall! incl)de RECo notesand details necessar! to acc)ratel!( com letel! and clearl! sho& ho& to constr)ct the

Reinforced Earth &alls6 In order for the &all constr)ction dra&in:s to ro'ide thisacc)rac!( com leteness and clarit!( it is cr)cial that the 4&ner or Cons)ltant ro'idecom ara7l! acc)rate( com lete and clear information in the contract doc)ments or other

re-7id comm)nications6 4ften the contract doc)ments contain a section de'otede3cl)si'el! to &all control data this arran:ement ma;es for efficient comm)nication ofthe necessar! information6

The &all constr)ction dra&in:s incl)de a com lete ele'ation 'ie& of the &all( as &ell asone or more cross sections and all necessar! details6 RECo s &all constr)ction dra&in:s&ill onl! incl)de a com lete lan 'ie& of the &all if one of the follo&in: is tr)e

• RECo has had to modif! the lan 'ie& ro'ided in the contract doc)ments6• The Reinforced Earth 'ol)me m)st 7e sho&n in relation to the location of s ecific

loads <s)ch as 7)ildin: fo)ndations=6

• A &all lan 'ie& is re )ired 7! the 4&ner s s ecifications6

8id )antities are ro'ided rior to 7id6 o&e'er( &all constr)ction dra&in:s are not ro'ided rior to 7id if the 4&ner s lans incl)de &all location( :eometr! anddimensions( )nless there are )n)s)al or com le3 iss)es that m)st 7e clarified 7! RECo orif s)7mission of &all constr)ction dra&in:s is re )ired 7! the 4&ner6

Since there is a &ide ran:e of &all desi:n details( an! of &hich ma! or ma! not 7e )sedin a artic)lar set of &all constr)ction dra&in:s( these details are itemi>ed and disc)ssedse aratel! in Section ?6*6

The Reinforced Earth Com an! does not re are re7ar 7endin: dia:rams or materialslists for cast-in- lace concrete str)ct)res6

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>&' ;eneral Notes

What to(ics are co-ered in the ;eneral Notes?In addition to the roBect title( the co'er sheet ro'ides :eneral notes co'erin: the

follo&in: to ics

• Ass)m tions re:ardin: soil materials( constr)ction methods and )alit! ofmaterials6

• Desi:n criteria for soils and s) lied materials( incl)din: &ho has res onsi7ilit!for determination of allo&a7le 7earin: ress)re( desi:nation of )ns)ita7lefo)ndation materials and methods for handlin: those fo)ndation materials6

• Wall la!o)t information6

• Constr)ction re )irements for 7ac;fill com action and storm &ater control( and

res onsi7ilit! for cast-in- lace concrete re7ar detailin:6• Conflictin: str)ct)res &ithin the Reinforced Earth 'ol)me( s)ch as manholes(

draina:e i es( iles( :)ardrail osts( a'ements and other str)ct)res6

• Materials s) lied 7! others( 7ac;fill )antities( nominal reinforcin: stri len:thsand recast anel finishes6

In addition( Bo7-s ecific notes are added as necessar! for comm)nication of roBectre )irements6

>&. Ele-ation

What information should the Owner or Owner s 4onsultant (ro-ide?

The follo&in: information is re )ired in order for The Reinforced Earth Com an! to rod)ce a com lete ele'ation dra&in: for constr)ction )se

A6 Wall Control Dra&in:s <4&ner s Contract /lans=

• Site lan - 7e:innin: and endin: stations for &all( centerline of road&a!( ali:nment

of front face of &all( offsets to front face of &all( c)r'e data </T( /C( radi)s ofc)r'at)re=6

• Ele'ation - to of &all ele'ations <:)tter line( to of 7arrier or co in:=( finished:rade ele'ations in front of &all <not le'elin: ad ele'ations - see Section "6# fore3 lanation=6

• T! ical section thro):h &all - the t! ical section ermits a more detailed loo; at

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the s!stem 7ein: desi:ned and sho)ld clearl! indicate the minim)m de th <notele'ations - see Section "6# for e3 lanation= of to of le'elin: ad 7elo& finished:rade( the oint on the str)ct)re &here to of &all ele'ations are :i'en( and the

oints to &hich offsets are referenced < e.g. ( front face of anels or face of 7arrieror co in:=6

86 4ther Contract /lans - 4nl! re )ired 7! RECo if this information is not ro'ided inWall Control Dra&in:s <see a7o'e=

• 8rid:e lans - a7)tment2&all interface( ile locations2interferin: iles( 7rid:e loads6

• Draina:e lans - locations of inlets( o)tlets( i es etc6

• Li:htin: lans - locations and t! es of oles to 7e installed adBacent to the &all ormo)nted on the &all 7arrier6

• Utilit! lans - t! e( si>e and location of an! )tilities r)nnin: )nder( thro):h or

adBacent to the &all or &hich are to 7e mo)nted on the &all 7arrier6• Si:n lans - t! e( si>e and location of an! si:ns that ma! interfere &ith an! art of

the &all( es eciall! the reinforcin: stri s6

• 4ther details - s)ch as co in: or 7arrier mo)nted on the Reinforced Earth &all6

What is shown on a finished ele-ation drawing?

After recei'in: the information o)tlined in the t&o lists a7o'e( The Reinforced EarthCom an! is a7le to rod)ce &all ele'ation dra&in:s6 The sam le &all ele'ation dra&in:in Fi:)re "6,6$ ill)strates &hat is t! icall! ro'ided

• Contractor s constr)ction len:ths and ele'ations for each section of le'elin: ad6

• /recast anel confi:)ration <7oth standard anels and s ecial c)t anels=( incl)din:n)m7er of tie stri s er anel6

• To of &all ele'ations <ma! 7e :i'en at :)tter( to of 7arrier or to of co in:=6

• T! e of str)ct)re to 7e constr)cted on to of the &all6

• Location of draina:e str)ct)res6

• Len:th and location of the reinforcin: stri s <see Section "61 for more informationconcernin: reinforcin: stri s=6

• Ma3im)m a lied 7earin: ress)re )nder the &all for each reinforcin: stri len:th<to aid the re'ie&er of the desi:n calc)lations=6

• /anel col)mns n)m7ers - an es eciall! )sef)l tool &hen disc)ssin: the &all o'erthe tele hone or trac;in: constr)ction ro:ress in the field6

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>&2 = (ical Sections

What information is (resented on the Reinforced Earth wall t (ical section?

It is 'er! hel f)l to RECo &hen the 4&ner or Cons)ltant ro'ides a t! ical cross sectionthro):h the &all<s= sho&in: the information listed 7elo&6 If a cross section is not

ro'ided( ho&e'er( it is essential that the listed information 7e ro'ided in &ritin:6

In :eneral( the Reinforced Earth t! ical section &ill incl)de the follo&in: information<see Fi:)res "6.6$ thro):h "6.6%=

Information /ro'ided Sho)ld 8e /ro'ided 8!

• Location of front face of &all • 4&ner

• /ro osed finished :rade in front of &all • 4&ner

• To -of-&all treatment < e.g. ( )nfinished(co in:( 7arrier( a7)tment( other=

• 4&ner

• Reinforcement len:th • RECo

• Le'elin: ad ele'ation • RECo

• Limits of select 7ac;fill <sometimes

called P:ran)lar materialP=

• RECo

• Em7edment de th • RECo( )nless s ecified 7! 4&ner

• Limits of e3ca'ation and random 7ac;fill <ma! or ma! not 7e sho&n(de endin: on roBectcirc)mstances2re )irements=6

• 4&ner

Details to s) lement the cross section &ill 7e added as needed6 T! ical details fo)nd in

&all constr)ction dra&in:s are disc)ssed in Section ?6*6

>&% = (ical ,anel and 4onnection Details

What is the configuration of a t (ical (anel?

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/recast concrete facin: anels for Reinforced Earth &alls are rod)ced in a 'ariet! ofsi>es and sha es so that some com7ination of them &ill conform to nearl! an! &allconfi:)ration or dimensions6 With the e3ce tion of the s ecial confi:)ration S )are orLar:e Rectan:)lar /anels( Reinforced Earth anels can 7e reco:ni>ed 7! their

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characteristic cr)ciform sha e6 The anels ha'e earsX rotr)din: from each side( so thecenterline of the anel Boint is the centerline of the o'erla in: ears of adBacent anels<Fi:)re "6%6$=6 This sha e allo&s anels to interloc; in the lane of the &all &itho)tcom romisin: facin: fle3i7ilit!6

How is facing fle)ibilit achie-ed?

Fle3i7ilit! of the facin: is achie'ed 7! )sin: relati'el! small anels ha'in: shi la Boints 7)t no other anel-to- anel connections6 This fle3i7ilit! is maintained 7! s eciall!fa7ricated elastomeric 7earin: ads that s) ort the anel a7o'e &hile re'entin: anel-to- anel contact6 There is no other connection 7et&een anels6 The fle3i7ilit! of this

Boint s!stem allo&s the anels to 7e adB)sted hori>ontall! d)rin: installation as &ell asmo'e 'erticall! in case of settlement <note that &alls )sin: lar:er anels are less fle3i7leand are( therefore( some&hat less tolerant of differential settlement=6 The dimensionaltolerance desi:ned into the Boints also ermits anel rotation a7o)t the Boint centerline(

allo&in: a &all to follo& a c)r'ed ali:nment made ) of a series of short chords oflen:th e )al to a anel s nominal &idth6

In addition to creatin: facin: fle3i7ilit!( the anel Boints are an im ortant art of the &alldraina:e s!stem6 To re'ent soil articles from clo::in: them( the Boints are rotected 7!stri s of filter cloth( *6%1m <$" in= &ide( a lied as the anels are erected6 The filtercloth cannot 7e seen from the front of the &all d)e to the shi la desi:n of the anel

Boints6

Three t! es of facin: anels ma;e ) the maBorit! of the anels in an! &all - center( 7ottom and to anels6 Each is descri7ed 7elo& and sho&n in Fi:)res "6%6,a and "6%6,76

• Center /anels

• The maBorit! of the anels in most &alls are center anels( desi:nated t! e A6 AnA anel is $61 m <%6?, ft= hi:h and meas)res $61 m &ide 7et&een the centerlines ofthe anel ears6 A anels :enerall! co'er the internal &all area( a&a! from the

eri her!( and are t! icall! sho&n as s )ares on the ele'ation 'ie& in the &allconstr)ction dra&in:s6

• 8ottom /anels

• A anels can also 7e 7ottom anels( in &hich case t! e , anels are )sed atalternate anel locations alon: the le'elin: ad <7et&een the As=6 The , anel ise3actl! the to half of an A anel and( 7eca)se it sits in the same orientation as theA anels( it fills the :a s 7et&een them6 When dictated 7! &all hei:ht andfo)ndation ele'ation re )irements( anel t! es $ and <a $ is $6,1 times thehei:ht of an A( &hile a is $61 times the hei:ht of a , = ma! 7e )sed instead - or incom7ination &ith - A and , anels6 When )sed in com7ination &ith A and ,

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• anels( $ and anels also allo& the le'elin: ad to ste ) or do&n in incrementsof *6.01 m <$6,. ft= instead of a half anel ste hei:ht of *601 m <,6%# ft= <Fi:)re"6%6,=6 All 7ottom anels are sho&n in Fi:)re "6%6.6

• To /anels

• /anel t! es C ( D( E ( F ( G ( H ( ( and L are al&a!s )sed at the to of the &all(ens)rin: a hori>ontal to line &here that is re )ired6 A stepped &all to can 7eachie'ed 7! the airin: of a C anel &ith a G anel( a D &ith an H ( an E &ith a ( (and an F &ith an L ( rod)cin: a series of *6$"0 m <*6#$1 ft= ste s <these ste s arees eciall! )sef)l for follo&in: a :rade 7eneath a cast-in- lace co in: or 7arrier=6/anels HN and HM are )sed &hen a s ecific , $ slo e is re )ired6 All to anelsare sho&n in Fi:)re "6%6.6

The anels descri7ed a7o'e are those )sed most fre )entl!6 Non-t! ical anel t! es(s)ch as corner elements( sli Boints and other slo e-to anels( are disc)ssed in Section ?6

How are reinforcing stri(s connected to (anels?

Reinforcin: stri s are connected to anels )sin: :al'ani>ed steel tie stri s <Fi:)re "6%6%6=6A tie stri s trian:)lar head and the adBacent ortion of its t&in connection ta7s are castinto the concrete( &ith the 7alance of the ta7s rotr)din: from the 7ac; of the anel6 Theta7s( se arated 7! B)st eno):h s ace for insertion of a reinforcin: stri ( ha'e re )nchedholes thro):h &hich the stri is 7olted6 The n)m7er of tie stri s cast into a anel isindicated in the anel nomenclat)re 7! a n)merical s)ffi3 to the anel desi:nation <a

anel desi:nated PA% is a t! e A anel &ith % tie stri s=6

How is a (anel reinforced internall ?

All Reinforced Earth &all anels contain re7ar6 The )antit! of re7ar is determined fromthe reinforcement desi:nation( PR3(P &here P3P is the n)m7er of 'ertical 7ars in the

anel6 R% is the minim)m confi:)ration <Fi:)re "6%61=( &hile R# reinforcement adds a air of 'ertical 7ars flan;in: the center tie stri s6 Reinforcement t! es R% and R# are themost common( &ith other confi:)rations )sed for hea'ier loadin: conditions6 Therefore(a com lete anel nomenclat)re &o)ld 7e A%R%( and this information is sho&n on the

anel castin: dra&in:s and )sed as the iece mar; for man)fact)rin: and fieldidentification6

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>&5 Reinforcing Stri(s

Reinforced Earth hi:h adherence < A= reinforcin: stri s are fa7ricated of str)ct)ral steelconformin: to ASTM A10,( Grade #1( and are :al'ani>ed accordin: to ASTM A$,.6

The cross section is constant at 1* 3 % mm <$6?#? 3 *6$10 in=6 The stri s are called Phi:hadherenceP d)e to the hi:h stri -to-soil shear resistance created 7! the ri7s on the to and 7ottom s)rfaces <Fi:)re "616$=6 The stri len:ths 'ar! accordin: to the str)ct)re s desi:n6The s) lied len:th is ne'er shorter than the nominal len:th sho&n on the dra&in:s( 7)tma! e3ceed it 7! as m)ch as *6$1m <# in=6

Reinforcin: stri s are attached to the tie stri s 7! ASTM A.,1 7olts( $,61 mm diameter 7! ., mm lon: <*61 in 7! $6,1 in=6 For desi:n( the controllin: cross section of the stri isthe f)ll cross section( not the red)ced section at the 7olt hole <7eca)se the red)ced sectionis rotected a:ainst corrosion on 7oth the to and 7ottom 7! the tie stri =6 Fi:)re "616,ill)strates the connection of the reinforcin: stri to the tie stri 6

>&8 3e-eling ,ad Ste(s

What determines the configuration of the le-eling (ad? What information is needed tochoose the location of the (ad ste(s?

The $1* m thic; 7! .** m &ide <# in 7! $, in= )nreinforced concrete le'elin: ad isdesi:ned &ith ste s ositioned to minimi>e the amo)nt of &all material 7elo& the4&ner-s ecified minim)m em7edment line <Fi:)re "6#6$=6 To :i'e &all desi:ners thefle3i7ilit! to achie'e this :oal( The Reinforced Earth Com an! recommends that the4&ner or Cons)ltant not s ecif! le'elin: ad len:ths and ele'ations 7)t sim l! definethe finished :rade in front of the &all and the minim)m re )ired em7edment de th6RECo en:ineers can then select the most cost-efficient com7ination of anels and ste sconsistent &ith the 4&ner s re )irements6

What is the relationshi( between the le-eling (ad ste( and the (anel 7oint centerline?

The le'elin: ad len:ths sho&n on the ele'ation dra&in: are not h!sical len:ths of thele'elin: ad( 7)t rather nominal distances from the centerline of the anel Boint to the endof that artic)lar ad section6 The relationshi 7et&een the act)al end of ad andcenterline of anel Boint is sho&n on the standard desi:n dra&in:s in the PT! icalLe'elin: /ad Ste DetailP <Fi:)re "6#6,=6

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B.0 TY$ICAL DESIGN DETAILS

The econom!( safet! and aesthetics of a Reinforced Earth str)ct)re can 7e :reatl!enhanced 7! ositi'e and consistent interaction amon: the 4&ner( the Cons)ltant and

The Reinforced Earth Com an!6 This interaction sho)ld start at the earliest sta:e of the roBect and contin)e thro):h the desi:n and constr)ction hases6 S)ch comm)nicationnot onl! ma3imi>es the 4&ner s2Cons)ltant s )nderstandin: of the Reinforced Earths!stem s ossi7ilities and 7enefits for the roBect( 7)t it also ena7les the Reinforced Earthdesi:ners to s)::est a roaches &hich &ill enhance the 'al)e and f)nctionalit! of thefinished rod)ct6

8ased on the a7o'e idea of ma3imi>in: )nderstandin: of the Reinforced Earth s!stem(this section re'ie&s the 'ario)s desi:n details that ena7le a Reinforced Earth str)ct)re to

7est meet the desi:n and f)nctionalit! needs of a roBect6 Section ? is 7ro;en do&n intofo)r :eneral cate:ories of details( as follo&s

S!stem Accessories Related Str)ct)res Draina:e Details

?6$ Sli @oints ?60 Traffic 8arriersJ ?6$, Draina:e DetailsJ?6, 8)tt @oints ?6" /ara etsJ?6. Corner Elements ?6? 8rid:e SeatsJ Geometric Details?6% Co in: ?6$* ori>ontal Incl)sions?61 Slo e-to /anels ?6$$ +ertical Incl)sions ?6$. Ac)te Corners?6# Connections ?6$% C)r'es

?6$1 Tiered Walls

JThese str)ct)res and details are desi:ned 7! the 4&ner or 4&ner s Cons)ltant6 The!are sho&n on RECo s dra&in:s for com leteness6

S5%te: Acce%%orie%

@&' Sli( oints

What are sli( 7oints? Where are the used?

Sli Boints are contin)o)s 'ertical Boints ro'ided at selected locations alon: a ReinforcedEarth str)ct)re6 A sli Boint re laces the normal 'ertical Boint s!stem( s)7stit)tin: a'ertical se aration 7et&een adBacent anels that e3tends the f)ll hei:ht of the &all6 Thesections of &all on either side of the sli Boint are( therefore( a7le to 7eha'einde endentl! of each other6 The sli Boint desi:n )ses either an e3 osed sli Boint anelha'in: its o&n reinforcin: stri s <Fi:)re ?6$6$= or a hidden P7ac;) P anel in the 7ac;fill

7ehind the facin: anels <Fi:)re ?6$6,=6 8oth anel t! es re'ent loss of 7ac;fill thro):hthe Boint6

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There are fo)r rimar! reasons to )se sli Boints

• To ro'ide additional facin: fle3i7ilit! for se'ere differential settlement d)e tofo)ndation conditions6 Normal facin: fle3i7ilit! can accommodate ) to $differential settlement <$ m settlement alon: $** m of &all len:th=( &hile ro erl!

s aced sli Boints can si:nificantl! increase a Reinforced Earth &all s differentialsettlement tolerance <Fi:)re ?6$6.=6 See Section 06% for a more detailed disc)ssionof differential settlement6

• To address the s ecial case of differential settlement &here &all fo)ndationconditions chan:e a7r) tl! <Fi:)re ?6$6%=( or &hen a Reinforced Earth 7rid:e&in:&all Pste s offP the ri:id concrete fo)ndation of the heel of the a7)tment ontothe relati'el! more fle3i7le soil fo)ndation 7e!ond the heel6 A sli Boint at thistransition re'ents )nsi:htl! and otentiall! dama:in: facin: distress6

• To co'er and add fle3i7ilit! to the transition from a Reinforced Earth str)ct)re to acast-in- lace concrete str)ct)re( as &hen a retainin: &all a7)ts the head&all of a

c)l'ert <Fi:)re ?6$61= or the concrete &in:&all of a 7rid:e6• To accommodate a c)r'e ha'in: a radi)s less than 061 m <,1 ft= <Fi:)re ?6$6#=6

Altho):h not necessaril! a sit)ation re )irin: additional facin: fle3i7ilit! as in thethree sit)ations disc)ssed a7o'e( sli Boints are )sed in a small radi)s c)r'e to

re'ent the PearsP of the cr)ciform anels from interferin: &ith each other <seeSection "6%=6 C)r'in: the &all to a small radi)s re )ires more Boint rotation than is

ermitted 7! the clearance 7et&een the concrete s)rfaces of the adBacent anel ears6See Section ?6$% for f)rther disc)ssion of c)r'ed Reinforced Earth &alls6

@&. 6utt oints

What are 6utt oints? Where are the used?

A 7)tt Boint is a 'ertical 7rea; in the &all face &here a &all a7r) tl! chan:es direction <acorner or an:le=( or &here a &all ends adBacent to another str)ct)re6 8)tt Boints res)ltin:from direction chan:e are not co'ered <&hereas most sli Boints are co'ered - see Section?6$=6 8)tt Boints :enerall! consist of a ,* mm <.2% in= o en Boint 7et&een t&o col)mns of

recast anels( or 7et&een the recast anels and the adBacent str)ct)re6 Geote3tile fa7ricis adhered to the fill side of the Boint to re'ent loss of 7ac;fill6 While 7)tt Boints are

t! icall! )sed for chan:es in &all ali:nment in e3cess of $"* °( the! ma! also 7e )sed for?* ° 7ends on lo& &alls &here aesthetics is not a concern6

Se'eral t! ical 7)tt Boint confi:)rations are descri7ed 7elo&6

• Wall &ith a ,0* ° 7end <Fi:)re ?6,6$=6 Note that this confi:)ration allo&s the )se ofstandard cr)ciform anels in one col)mn and anels c)t to fit a 'ertical lane in the

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adBacent col)mn( red)cin: the n)m7er of s ecial anel t! es and sim lif!in: the&all erection rocess6

• Wall &ith an o7t)se 7end <Fi:)re ?6,6,=6 This confi:)ration also allo&s for the )seof one col)mn of standard anels and one col)mn of c)t anels( 7)t the c)t anels

for an o7t)se 7end m)st 7e mitered to ens)re ro er &all ali:nment6

• Wall &ith a ?* ° 7)tt Boint <Fi:)re ?6,6.=6 This detail &or;s &ell for lo& &alls( 7)tre )ires that anels on 7oth sides of the Boint 7e c)t anels6 When aestheticsco)nts( a corner element <see section ?6$1= :i'es a more finished loo;6 A ?* ° 7)tt

Boint ma! also 7e )sed for medi)m hei:ht &alls( 7)t certain modifications to thedetail are re )ired and m)st 7e determined on a Bo7-s ecific 7asis6

• At the interface 7et&een a Reinforced Earth &all and a cast-in- lace str)ct)re<Fi:)re ?6,6%=6 Note the $** 3 $** mm <% 3 % in= cast-in- lace li in front of the

recast anel or the $** 3 $1* mm <% 3 # in= notch in the cast-in- lace str)ct)re torecei'e the Reinforced Earth anels6 The li or notch hides or mas;s an!mo'ement of the more fle3i7le Reinforced Earth str)ct)re relati'e to the ri:id cast-in- lace str)ct)re6 It also hides or minimi>es the 'isi7ilit! of the remolded Bointfiller 7et&een the cast-in- lace and Reinforced Earth str)ct)res6

• At the interface 7et&een a Reinforced Earth &all and an e3istin: str)ct)re <Fi:)re?6,61=( &here no li is a'aila7le <as descri7ed immediatel! a7o'e= and &here thefront face ali:nments m)st 7e offset( re'entin: )se of a sli Boint anel <seeSection ?6$=6

@&2 4orner Elements

What are corner elements and where are the used?

Corner elements are s eciali>ed facin: anels that chan:e the &all ali:nment at a artic)lar oint <Fi:)re ?6.6$=6 Their sha e is similar to that of sli Boints <see Section?6$= e3ce t the! are folded a7o)t their 'ertical centerlines6 The adBacent re:)lar facin:

anels are c)t off 'erticall!( B)st li;e the anels flan;in: a re:)lar sli Boint6 An:les lessthan $#, ° are handled &ell 7! corner elements( &hile an:les 7et&een $#, ° and $"* ° are

7est handled as c)r'es <see Section ?6$%=6 F)ll si>e corner elements are the same hei:htas re:)lar facin: anels and ha'e t&o tie stri s at ele'ations matchin: those on there:)lar anels6 Therefore( corner elements are held in lace 7! their o&n reinforcin:stri s6

An! corner element t)rnin: an an:le of less than ?*Q is( 7! :eometric definition( ac)te<Fi:)re ?6.6$=6 Since some ac)te corners re )ire s ecial desi:n treatment( de endin: on

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the relationshi 7et&een the an:le t)rned and the hei:ht of the &all( the reader is referredto Section ?6$.( Ac)te Corners( to determine if this s ecial desi:n treatment is re )iredon a artic)lar roBect6

Altho):h almost an! an:le can 7e achie'ed )sin: a 7)tt Boint <Fi:)res ?6,6$( ?6,6, and

?6,6.=( a more finished a earance res)lts from )sin: a corner element as sho&n inFi:)res ?6.6$( ?6.6,( and ?6.6.6

@&% 4o(ing

What is a co(ing and what is its (ur(ose?

A co in: is a cast-in- lace or recast architect)ral treatment that creates smooth( cleanlines at the to of a Reinforced Earth &all <Fi:)re ?6%6$=6 Whether the to anels all end

at the same ele'ation or the! ste to follo& a slo in: :rade( the co in: o'erhan:s thefront of the &all 7! a minim)m of 1* mm <, in=( hidin: an! anel-to- anel ele'ationchan:es <Fi:)re ?6%6,=6 As sho&n in Fi:)re ?6%6.( cast-in- lace co in: ma! 7e laced'erticall! to finish off anel ed:es aro)nd a 7rid:e a7)tment seat <also see Section ?6?=6

In section( the recast co in: )nit is an in'erted letter U <Fi:)re ?6%61=( &ith liftin:anchors for lacement <Fi:)re ?6%6#=6 /recast co in: )nits are t! icall! cast in .6* m <$*ft nominal( ?6"% ft act)al= sections ha'in: s )are ends <Fi:)re ?6%6%=6 The .6* m len:the3actl! matches the s acin: of e'er! second 'ertical Boint alon: the to of the &all6

8efore installin: recast co in:( the to of the &all m)st 7e smooth and free of ste s or

irre:)larities6 To accom lish this( le'el-) concrete fill is cast on to of the anels6 Thesmooth finished :rade of this concrete fill m)st follo& a line *6,. m <? in= 7elo& the toof co in: ele'ation6 To anels that are to recei'e recast co in: are man)fact)red &ithdo&els rotr)din: from their to s to tie in the le'el-) concrete <these do&els ma! ha'eto 7e field-c)t to fit=6 4nce the le'el-) concrete is set( the recast co in: )nits are

laced on the to of &all( se arated 7! the $. mm <*61 in= o en Boints disc)ssed a7o'e6

When is cast*in*(lace co(ing recommended in (lace of (recast co(ing?

Cast in lace co in: is recommended in sit)ations &here the &all follo&s a si:nificanthori>ontal or 'ertical c)r'e6 Since recast co in: sections are cast &ith s )are ends(

Boints 7et&een co in: sections <as seen from the front of the &all= ma! 7ecome too ti:htor too &ide( de endin: on &hether the radi)s oint is in front or 7ehind the &all face(res ecti'el!6 Cast-in- lace co in: sho)ld 7e )sed at sli Boints so the in- lacecharacteristics and meas)rements of the sli Boint can 7e accommodated <Fi:)re ?6%60=6Refer to Fi:)res ?6%6$ and ?6%6, for cast-in- lace co in: details6 Cast-in- lace co in:sho)ld also 7e )sed &here a &all has a hori>ontal or 'ertical 7end6

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Fi:)re ?6%6" sho&s cast-in- lace co in: that s) orts fence osts( &hile Fi:)re ?6%6?sho&s ho& co in: &or;s &ith a draina:e ditch6 A cast-in- lace co in: enclos)re is often)sed at the ends of slo in: &alls <Fi:)re ?6%6$*=6 This co in: enclos)re act)all! retainsthe lo&est :rade differential and e3tends the architect)ral lines of the co in: to theintersection of the front-of-&all and 7ac;-of-&all :ro)nd lines6

@&5 Slo(e*to( ,anels

What are the standard slo(ing to(*of*wall treatments for Reinforced Earth walls?

Si:nificant to -of-&all slo es are re )ired at the ends of man! &alls6 Reinforced Earthfacin: anels are man)fact)red in standard slo es of , $( % $ and " $ <Fi:)res ?616$( ?616,and ?616.( res ecti'el!=6 It is hi:hl! recommended that( &hene'er ossi7le( &alls 7edesi:ned &ith one of these slo es for 7est aesthetics and ease of constr)ction6 Altho):h a

co in: is often recommended as the to -of-&all treatment( &alls &hich )se an! of thesethree slo es ma! 7e acce ta7le &itho)t a co in: since the to s of the anels are all inline6

@&8 4onnections

How are reinforcing stri(s connected to (recast (anels?

The anchora:e de'ice to &hich reinforcin: stri s are 7olted is the tie stri 6 Each tie striis cast into the facin: anel &ith its air of connection ta7s rotr)din: ?* mm <.61 in=from the 7ac; face of the anel <Fi:)re ?6#6$=6 Attachment of a reinforcin: stri sim l!re )ires insertin: the reinforcement 7et&een the connection ta7s so the 7olt holes ali:n(

lacin: a 7olt ) from the 7ottom( installin: a &asher and n)t and ti:htenin: the n)t6 Theres)lt is a ositi'e( do)7le shear connection6

When are other $inds of connections are necessar ?

When the reinforcin: stri desi:n len:th e3ceeds the man)fact)rin: len:th limit( ?601 m<., ft=( t&o reinforcin: stri s m)st 7e connected to:ether in the field to achie'e thedesi:n len:th6 These reinforcin: stri s can 7e connected in either of t&o &a!s(de endin: on the finished len:th re )ired and the load to 7e carried6 Fi:)re ?6#6, sho&sa s lice created 7! la in: one reinforcin: stri o'er the other and connectin: them &ithone 7olt <a sin:le shear connection=6 The s lice in Fi:)re ?6#6. re )ires the t&oreinforcin: stri s to 7e laced nearl! end-to-end( sand&iches them 7et&een t&o s lice

lates and )ses t&o 7olts in do)7le shear( each assin: thro):h 7oth s lice lates and onereinforcin: stri 6

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Another t! e of connection is )sed &hen reinforcin: stri s m)st 7e shifted in the field toa'oid o7stacles s)ch as draina:e inlets or i es in the 7ac;fill6 In these sit)ations( alen:th of :al'ani>ed an:le iron is 7olted to t&o or more hori>ontall! adBacent tie stri s ont&o adBacent anels6 A reinforcin: stri can then 7e 7olted an!&here alon: the len:th of

the an:le sim l! 7! drillin: or )nchin: a 7olt hole at that location6 Fi:)res ?6#6%a and?6#6%7 sho& ho& the an:le is 7olted to the tie stri ( ho& a reinforcin: stri -to-tie striconnection can incl)de an an:le( and ho& a reinforcin: stri is attached directl! to anan:le a&a! from the tie stri 6

Relate/ Str&ct&re%

@&< =raffic 6arriers

What t (es of traffic barriers are used with Reinforced Earth structures? Are therean s(ecial design considerations?

AAS T4 Section ,606$( +ehic)lar Railin:s <Reference $=( ro'ides a detaileddescri tion of the a ro'ed t! es of traffic 7arriers( incl)din: their :eometr! and thestandard loadin: conditions to 7e desi:ned for6 This section deals &ith traffic 7arriersthat are installed 7oth 'erticall! and hori>ontall! close to the to of the anels of aReinforced Earth &all( in s)ch a manner that the &all ma! ha'e to resist 7arrier im actloadin: <Reference ,( Reference .=6 ot disc$ssed are 7arriers fo)nded entirel! on non-reinforced soil a7o'e and 7ac; from the to of the &all < i.e. ( on a fill slo e risin: from theto of the &all= or those located so far 7ac; from the &all face that loads from the 7arrierdo not infl)ence the &all desi:n6

T&o t! es of traffic 7arriers are t! icall! )sed on to of Reinforced Earth &alls6 Eachm)st meet artic)lar desi:n re )irements and re )ires that certain desi:n modifications

7e made to the &all as &ell6

• A concrete 7arrier s!stem consistin: of a concrete 7arrier or rail str)ct)rall!connected to a concrete moment sla7 cast directl! on the Reinforced Earth 7ac;fill<7)t isolated from the Reinforced Earth &all anels=6 The 7arrier is t! icall! aP@erse!P sha e or a state D4T s artic)lar 'ersion thereof <Fi:)re ?606$a( cast-in-

lace and Fi:)re ?606$7( recast=( 7)t rail-t! e 7arriers ma! 7e mo)nted on themoment sla7 as &ell6 In all cases( the moment sla7 m)st 7e si>ed to re'ento'ert)rnin: and slidin: of the 7arrier s!stem d)rin: im act6 Since the cast-in- lacemoment sla7 <or the 7ase of the recast 7arrier )nit= e3tends o'er the to s of the

anels to form a co in:( a recess into &hich the anels fit m)st 7e desi:ned in the)nderside of the sla7 or the recast 7arrier( and a ositi'e 7ond 7rea;er m)st 7e

ro'ided to ass)re isolation of the 7arrier from the anels6 Walls s) ortin: this

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t! e of 7arrier m)st 7e desi:ned for an additional load of ,? ;N2m <,*** l72ln ft= of&all( &ith the additional load carried entirel! 7! the to la!er of reinforcin: stri s<Reference .=6

8efore installin: a recast 7arrier( the to of the &all m)st 7e smooth and free of

ste s or irre:)larities6 To accom lish this( le'el-) concrete fill is cast on to of the anels <B)st as is done &ith recast co in: K see Fi:)res ?6%6% and ?6%61=6

• A fle3i7le ost and 7eam 7arrier s!stem <Fi:)re ?606,=( &ith osts dri'en directl!into the Reinforced Earth 7ac;fill or installed in concrete-filled forms laced d)rin:

7ac;fill lacement and com action6 The osts sho)ld 7e no closer than $ m <. ft=to the 7ac; face of the anels6 Walls s) ortin: this t! e of 7arrier m)st 7edesi:ned for an additional load of %6." ;N2m <.** l72ft= of &all( &ith the additionalload carried entirel! 7! the to t&o la!ers of reinforcin: stri s <Reference .=6

@&> ,ara(ets

What are ,ara(ets? Where are ,ara(ets used? What is the difference between a ,ara(et and a =raffic 6arrier?

A ara et is a cast-in- lace or recast concrete rail located directl! or nearl! on to of aReinforced Earth &all6 Altho):h ara ets resem7le traffic 7arriers( the! are :enerall!desi:ned onl! for edestrian or 7ic!cle loads <Reference $=( not for 'ehic)lar loadin:6

Ne'ertheless( ara ets )se a moment sla7 for sta7ilit! <as do traffic 7arriers - see Section

?60=6 This cast-in- lace sla7 ma! also ser'e as a side&al;( as ill)strated in Fi:)re ?6"6$6/ara ets are :enerall! rotected from 'ehic)lar im act 7! a standard traffic 7arrier ornon-mo)nta7le c)r7 at the ed:e of the road&a!6

@&@ 6ridge Seats

How does a Reinforced Earth wall fit around a bridge seat?

The easiest &a! to detail a Reinforced Earth &all aro)nd a 7rid:e seat is to )se hori>ontal

and 'ertical co in:6 As sho&n in Fi: ?6?6$( co in: co'ers the e3 osed ed:es of theReinforced Earth anels and art of the end of the 7rid:e seat6 With this treatment( theco in: is contin)o)s aro)nd the entire end 7ent <do&n the end of the 7ac;&all and acrossthe end of the seat( across the front face( then across the other end of the seat and 7ac; )the 7ac;&all=6 Usin: this method :i'es 7oth the desi:ner and the contractor somefle3i7ilit! since &all anels a7)t the o)ter ed:es of the 7ac;&all and 7rid:e seat(

ermittin: 'ertical adB)stments in the field if re )ired6

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Another &a! to detail a Reinforced Earth &all at a 7rid:e seat is to )se a chee;&all6 Inthis desi:n( the c)t ed:es of the Reinforced Earth anels 7)tt ) a:ainst the 7ac; face ofthe 7rid:e seat6 The chee;&all is cast er endic)lar to and as an e3tension of the 7rid:eseat( &ith a li &hich hides the 7)tt Boints 7et&een the chee;&all and the adBacentReinforced Earth anels <Fi:)re ?6?6, and Fi:)re ?6?6.=6 The co in: ends at the front

ed:e of the 7rid:e seat <&hich is also the front ed:e of the chee;&all= and the front faceof the chee;&all is fl)sh &ith the o)tside face of the co in:6

What should be the clearance between a Reinforced Earth wall and bridge (iles withinthe reinforced bac$fill?

When a 7rid:e seat is s) orted on iles( it is necessar! to ro'ide clearance 7et&een the iles and the 7ac; face of the Reinforced Earth &all anels <Fi:)re ?6?6%=6 To re'entinterference 7et&een the reinforcin: stri s and the iles( the anel-to- ile clearancesho)ld 7e a ini $ of *61 m <$61 ft=( 7)t more clearance ma! 7e re )ired de endin: onthe ile t! e and si>e6

4an reinforcing stri(s be added to the bridge seat to resist earth (ressures andhorizontal loads im(osed b the bridge?

Tie stri s cast into the 7ac; of a 7rid:e seat <Fi:)re ?6?61= ermit installation ofreinforcin: stri s to resist lateral forces <7oth earth ress)re and 7rid:e loads= a lied tothe seat6 In order for The Reinforced Earth Com an! to desi:n this detail( ho&e'er( the4&ner2Cons)ltant m)st ro'ide information a7o)t the loads comin: from the 7rid:e

s) erstr)ct)re6

@&'B Horizontal Inclusions 9Drainage Structures+ ,i(elines+ etc&:

What are Horizontal Inclusions? How are the dealt with?

ori>ontal incl)sions are str)ct)res &hich sit in or e3tend hori>ontall! thro):h the 7ac;fill of a Reinforced Earth str)ct)re and &hich ma! interfere &ith the normal lacement <either hori>ontal or 'ertical= of the reinforcin: stri s6 Fi:)re ?6$*6$ sho&s themost common hori>ontal incl)sion enco)ntered in Reinforced Earth &all desi:n( thedraina:e str)ct)re6

Draina:e str)ct)res )s)all! are located close to the 7ac; face of the recast &all anels6In this sit)ation( :al'ani>ed an:les are )sed not onl! to str)ct)rall! connect adBacent

recast facin: anels( 7)t also to re osition the reinforcin: stri s so the! can :o aro)ndthe draina:e str)ct)re <see also Section ?6# and Fi:)res ?6#6%a and ?6#6%7=6 The ideal

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location for a draina:e str)ct)re( as sho&n in Fi:)re ?6$*6,( is far eno):h 7ehind the &all anels to allo& the reinforcin: stri s to 7e s;e&ed to clear the o7stacle &itho)t re )irin:an:les to re osition the stri s6

/i elines are often enco)ntered in com7ination &ith draina:e str)ct)res located 7ehind

Reinforced Earth &alls6 In these sit)ations( the clear distance 7et&een the i e and the 7ac; face of the Reinforced Earth &all anels is critical in determinin: the lacement ofthe reinforcin: stri s6 If at all ossi7le( the location of the i e sho)ld 7e as sho&n inFi:)re ?6$*6.6

Fi:)re ?6$*6% sho&s a method that allo&s a draina:e str)ct)re to remain at a standardlocation &hile mo'in: the hori>ontal i eline f)rther 7ac; into the Reinforced Earth'ol)me to minimi>e reinforcin: stri -to- i eline interference6

Fi:)re ?6$*61 sho&s the detail for a i e assin: thro):h a &all6

@&'' Certical Inclusions

What are -ertical inclusions? How are the dealt with?

+ertical incl)sions are str)ct)res that sit in or e3tend 'erticall! thro):h the 7ac;fill of aReinforced Earth str)ct)re and otentiall! interfere &ith se'eral la!ers of reinforcin:stri s6 Some e3am les of 'ertical incl)sions are manholes and dee inlets( iles( or otherdee fo)ndations s) ortin: roadside a )rtenances6

In some sit)ations( 'ertical incl)sions can 7e laced in a Reinforced Earth str)ct)re&itho)t necessitatin: chan:es to the desi:n of the &all6 Manholes and i es often can 7eshifted arallel to the &all to a'oid interference &ith reinforcin: stri s6 /iles( on theother hand( are ositioned accordin: to 7rid:e desi:n re )irements and )s)all! cannot 7emo'ed or ha'e their ile-to- ile s acin: adB)sted to a'oid reinforcin: stri interference6For sit)ations in'ol'in: iles( the 7est &a! to minimi>e ile-stri interference is to ha'eade )ate clearance 7et&een the iles and the 7ac; of the &all6

When interference 7et&een 'ertical incl)sions and reinforcin: stri s cannot 7e a'oided(the lacement of the reinforcin: stri s can 7e adB)sted6 Fre )entl! this can 7e donesim l! 7! rotatin: the stri s aro)nd the 7olt( ) to a ma3im)m s;e& of $1Q <Fi:)re

?6$$6$=6 If reinforcin: stri s need to 7e s;e&ed more than $1 de:rees( calc)lations m)st 7e erformed to determine if additional stri s m)st 7e added near the 'ertical incl)sion toma;e ) for the red)ced stress-carr!in: and )llo)t ca a7ilities of the s;e&ed stri s6The ositions of the reinforcin: stri s ma! also 7e adB)sted 7! shiftin: the tie stri shori>ontall! rior to castin: the anels6 This method is recommended onl! if locations of'ertical incl)sions are ;no&n in ad'ance6 Alternati'el!( to allo& more fle3i7ilit! d)rin:constr)ction( anels to 7e located at 'ertical incl)sions can 7e cast &ith e3tra tie stri s6 A

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anel re )irin: onl! fo)r tie stri s 7! desi:n <t&o er le'el= co)ld 7e cast &ith si3 instead<Fi:)re ?6$$6,=6 In the field( reinforcin: stri s co)ld 7e attached to an! t&o of the threetie stri s per level ( de endin: on the recise location of the 'ertical incl)sion6

The final o tion for adB)stin: reinforcin: stri locations is to )se an an:le attached to the

tie stri s( as disc)ssed in Section ?6# and sho&n in Fi:)res ?6#6%a and ?6#6%76 Field-drilled holes in the an:le create reinforcin: stri attachment locations that are free ofinterference from the 'ertical incl)sion6

As sho&n in Fi:)re ?6$$6.( &alls &ith 'ertical incl)sions( es eciall! those at corners( can 7ecome 'er! com le3 7oth to desi:n and to 7)ild6 For this reason it is im ortant that theRECo desi:ner and the 4&ner2Cons)ltant 7e in close comm)nication d)rin: the desi:n

rocess6 This &ill lead to constr)ction dra&in:s that clearl! sho& the contractor ho& tocoordinate lacement of the incl)sions &ith erection of the &all &hile a'oidin: fieldchan:es that mi:ht red)ce desi:n safet! or increase costs6

Drai a-e Detail%

B.12 Drai a-e Detail%

What drainage details are associated with Reinforced Earth walls?

Good draina:e is critical to the ro er f)nctionin: of Reinforced Earth &alls6 E3ternal<to the &all= site draina:e desi:n de ends on the str)ct)re s location and localh!drolo:ical factors6 T! ical e3ternal draina:e feat)res incl)de s&ales 7ehind the

Reinforced Earth &all and2or catch 7asins and i elines6 See Section ?6$* for t! icalmethods of inte:ratin: draina:e str)ct)res &ith Reinforced Earth &alls6

The internal draina:e of Reinforced Earth &alls de ends on the characteristics of the 7ac;fill )sed in the str)ct)re6 For &alls 7)ilt in fill( the resence of the n)mero)shori>ontal and 'ertical o en Boints in the &all facin:( in com7ination &ith the freedrainin: nat)re of the :ran)lar 7ac;fill( ro'ides ade )ate draina:e6 To re'ent finer

7ac;fill articles from mi:ratin: into and clo::in: the Boints( the 7ac;fill side of each Boint is co'ered &ith a :eote3tile filter cloth6 <Fi:)re ?6$,6$=

For a Reinforced Earth &all 7)ilt in a c)t or in an area &here the :ro)nd &ater le'el is <or

ma! 7e= hi:her than the fo)ndation ele'ation of the &all( a erforated draina:e i e ma! 7e installed immediatel! 7ehind the facin: anels at the 7ase of the &all <Fi:)re ?6$,6,=6In addition( if recommended 7! the roBect :eotechnical en:ineer( a :ra'el chimne! drainor other s ecial draina:e de'ice ma! 7e re )ired on the 7ac; slo e of the e3ca'ation tointerce t :ro)nd &ater and channel it do&n 7ehind and thro):h or )nder the ReinforcedEarth &all <Fi:)re ?6$,6.=6

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Geo:etric Detail%

@&'2 Acute 4orners

How are acute corners designed?

When t&o Reinforced Earth &all se:ments are Boined 7! a corner element to form anac)te an:le <Fi:)re ?6$.6$=( the standard desi:n a roach ma! 7e acce ta7le or a s ecialdesi:n ma! 7e re )ired( de endin: on the ma:nit)de of the incl)ded an:le and the hei:htof the &alls <&hich determines the len:th of the reinforcin: stri s=6 Standard desi:nre )ires reinforcin: stri s to 7e er endic)lar to the 7ac; face of the str)ct)re 7)t allo&sfor ) to $1Q s;e&in:6 o&e'er( if the incl)ded an:le is small or the &all is hi:h<re )irin: lon: reinforcin: stri s=( the er endic)lar or ) -to-$1Q-s;e&ed stri s ma! notfit &ithin the confines of the corner6 Th)s( a Reinforced earth ac$te corner is a s ecialdesi:n in &hich the reinforcin: stri s close to the corner element are 7olted to the anelson both le:s of the an:le and the cross-7olted ortion is isolated from adBacent anels 7!sli Boints <Fi:)re ?6$.6,=6 A modified 'ersion of the standard ac)te corner desi:n( &iths;e&ed and ossi7l! e3tra reinforcin: stri s( is )sed &here &alls form ac)te corners &ith

7rid:e a7)tments or other s;e&ed o7str)ctions6

The ortion of the ac)te corner se arated 7! sli Boints is called the Pnose6P Since thecross 7oltin: of the reinforcin: stri s ma;es the nose m)ch stiffer than the rest of the&all( it is act)all! desi:ned as a 7in&all6 The nose is attached to the rest of theReinforced Earth mass 7! reinforcin: stri s 7olted to anels in the nose section ande3tendin: ast the sli Boints into the 7ac;fill of the standard desi:n ortion of the &all6The sli Boints are located after the last col)mn of anels re )irin: cross-7olted

reinforcin: stri s( and the sli Boints stri s themsel'es are desi:ned 7! the standarddesi:n method <stri s er endic)lar or s;e&ed ) to $1Q=6

@&'% 4ur-es

How are cur-es accommodated using flat (recast (anels?

A Reinforced Earth &all a ro3imates a c)r'e )sin: a series of $61 m <%6?, ft= lon:chords <$61 m is the nominal &idth of the anels and is the act)al distance 7et&een thecenterlines of the anel Boints=6 This roced)re chan:es the &all len:th sli:htl!( d)e tothe difference 7et&een the act)al len:th of the c)r'e and the s)m of the len:ths of thechords( 7)t this difference is minimal6 For e3am le( for a radi)s of .* m <$** feet=( thelen:th difference &o)ld 7e $6# mm <$2$# in= er anel6 Since anel Boints area ro3imatel! ,* mm <.2% in= &ide( this difference )s)all! can 7e accommodated 7!adB)stin: the Boint &idths as the &all is 7ein: 7)ilt6 When a recise fit is re )ired( s)chas for a c)r'ed &all that m)st fit e3actl! 7et&een t&o 7rid:e a7)tments or other fi3edo7Bects( s ecial c)t-to-fit anels are re )ired at the ends of the &all6

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What cur-ature limits should be considered?

A Reinforced Earth &all can 7e 7)ilt on a c)r'e &ith a radi)s as small as $1 m <1* ft=&itho)t an! s ecial adB)stments6 In addition( if the front face of the &all faces the centerof the c)r'e( e'en smaller radii can 7e achie'ed &ith a minor fa7rication chan:e in the

anel Boints or 7! )sin: 7ac;-) anels <Fi:)re ?6$%6$=6 Since c)r'es are so easil! 7)ilt&ith Reinforced Earth anels( an:les in &all ali:nment are often re laced &ith c)r'es<Fi:)re ?6$%6,=6

@&'5 =iered Walls

What are tiered walls and where are the used?

4ccasionall! the distance 7et&een the 7ac; face of a &all and the ri:ht-of-&a! limitlea'es ins)fficient room for the normal Reinforced Earth cross sectional dimension<reinforcin: stri len:th=6 In other locations( :eotechnical conditions ma;e e3ca'ationfor the re )ired Reinforced Earth cross section diffic)lt( ris;! and2or costl!( or 7earin:

ress)re or rotational sta7ilit! concerns ar:)e a:ainst a sin:le( 'er! hi:h &all6Sometimes sim l! architect)ral considerations recl)de )sin: a sin:le( hi:h &all face6

In s)ch circ)mstances( &alls ma! 7e stac;ed or tiered to reach the re )ired hei:ht6De endin: on the set7ac; distance 7et&een the tiers( the reinforcement len:ths for eachtier can 7e less than for a sin:le &all of the same total hei:ht( red)cin: e3ca'ation andselect 7ac;fill costs6 A f)rther cost red)ction res)lts from the shorter reinforcementlen:ths re )ired for certain tiered &alls as com ared to a sin:le &all of the same totalhei:ht6 Since str)ct)ral loadin: ma! 7e less se'ere for the indi'id)al tiers than for asin:le &all( the reinforcin: stri densit! ma! also 7e red)ced( ro'idin: an additionaleconomic 7enefit6

When the demand for tiered &alls arises from architect)ral2landsca in: considerations(Reinforced Earth is an ideal choice 7eca)se of the n)mero)s architect)ral o tionsa'aila7le to the desi:ner thro):h the 'ario)s facin: anel t! es and finishes6 4nee3am le of this t! e of tiered &all is the lanter &all sho&n in Fi:)re ?6$16$6

There are three :eneral desi:n cases for tiered &alls

• Minim)m offset of the tiers( &here the offset distance is less than $2,*th of the totalhei:ht of the str)ct)re6 In this case( each tier is desi:ned as if it &ere art of asin:le &all as hi:h as the total hei:ht of the tiers6 The reinforcin: stri s are as lon:as the! &o)ld 7e in a sin:le( f)ll-hei:ht &all( and there is no red)ction ine3ca'ation and 7ac;fill )antities6

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• F)ll offset of the tiers( in &hich each ) er tier is located f)ll! 7ehind the Ran;ineacti'e >one of the tier 7elo&6 In this case( each &all is desi:ned inde endentl!

7ased on the loads a lied 7! an! &alls or other s)rchar:es a7o'e it6

• /artial offset of the tiers( a sit)ation 7et&een minim)m and f)ll offset6 Desi:n forthis case is com le3 and an attem t is made to sim lif! s)ch &alls to either aminim)m or f)ll offset condition6

All tiered &all cases re )ire s eciali>ed consideration 7! Reinforced Earth Com an!en:ineers and sho)ld al&a!s 7e 7ro):ht to the attention of The Reinforced EarthCom an! for f)rther disc)ssion6

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Re!ere ce%

$6 Standard S ecifications for i:h&a! 8rid:es ( American Association of Statei:h&a! and Trans ortation 4fficials( $??# <Si3teenth Edition=( Di'ision I - Desi:n(

Section ,606$6

,6 Technical 8)lletin MSE -"( Crash Testin: of a /recast Traffic 8arrier Ato aReinforced Earth Wall( The Reinforced Earth Com an!( $??16


Di'ision I - Desi:n( Section 16"6$,6,6

RE Wall Design Manual

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