Anchored Retaining Walls
Transcript of Anchored Retaining Walls
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Foundation Engineering
Foundation Engineering
Prof. Mesut Pervizpour
Earth Retaining StructuresFlexible Retaining Walls:
Anchored sheet pile wallsBraced excavationsSlurr wallsStability of open cuts
For NAVFAC and other online manuals
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(including Army Corps of Eng, & FHWA)http://www.vulcanhammer.net/download/
Anchored sheetpile (H > 3m)
Anchored Sheet Pile Wall Design:
Additional support by tieback anchors (horizontal or inclined)
H Anchor e uc on n exura s resses an a era movemen o e wa
Walls can be constructed to larger heights
Reduction in required depth of embedment D
Design principles: free-end method, fixed end method, beam on elastic foundation method
Assumptions: rigid sheet pile, rotation of the wall about tie rod level, bottom
embedment ust sufficient for stabilit takin moment b tie rod location
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Anchored Sheet Pile Wall Design Free Earth Support Method:
Simplified Earth Pressure Distribution for Sands
The embedment is calculated by takingmoment about O
Simplified Earth PressureDistribution
The required anchorage resistance is:
= -
aapfpo
H
FzfO
z a p
a
Pa
PzcCz
p = (Kp Ka) (D zc)
D
For desi n increase calculated D b 20-50%.
Zfoften ~ H/4
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Find force in the tie rod.Find bending moment and pile section.
Anchored Sheet Pile Wall Design Free Earth Support Method:
Simplified Earth Pressure Distribution for Granular Backfill and
The embedment is calculated by takingmoment about O
D
Simplified Earth PressureDistribution
The required anchorage resistance is:
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aafpo zz
FzfO Sand
= a - p
a
a
Pa
eH eH: is the
weight of backfill
p = 4c - eH
PpD and surcharge
For desi n increase calculated D b 20-50%.
Clay ( = 0)
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Find force in the tie rod.Find bending moment and pile section.
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Anchored Sheet Pile Wall Moment Reduction
Rowes moment reduction method:
For walls in sand with.
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Anchored Sheet Pile Wall Moment Reduction
Rowes moment reduction method:
For anchored sheet pilewalls penetrating in tocohesive soils in terms ofstability number andflexibility number.
Stability number, obtain theration of Md/Mmax for
various log values (fromthe three plots).
Generate a plot of Md/Mmax
same steps as in granularsoils (described earlier).
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Example Anchored Sheet Pile Wall in Sand:Total embedment depth of the sheet pileForce in the tie rod er meter of wallSuitable piling section
about O (tie level):
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Example Anchored Sheet Pile Wall in Sand:
Mmax = (4.1 + 1) 167.9
Total length L of the sheet pile:
L = 10 + 6.2 = 16.2m
(4.1 + 4/3) 47.1
(4.1)(4.1/2) 23.5
(4.1)2 (4.1/3) 1.45
= 369.56 KNm/m
= 997 kip in/ft
H 265.01.53'44
Forces on the wall and the location of Mmax, x belowthe water level is shown in the figure, Equilibrium, Fx = 0:
Select the pile appropriate pilesection from the following tables
IIEI 1030
10 x = 4.1m (below water)
1.45x2 + 23.54x + 47.1 167.9 = 0X2 + 16.23x 83.31 = 0
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Example Anchored Sheet Pile Wall in Sand (Cont.):
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Momentof
SectionModulus
Area
Example Anchored Sheet Pile Wall in Sand (Cont.):
inertia
Example: 25ksi*46.8/12=97.5
97.5/(997/12)=1.17 0.96 0.76
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Example Anchored Sheet Pile Wall in Sand (Cont.):
Rowes moment reduction method:
observed < Mmax calculated via. Free-earthsupport method.Rowe reduce the moment, factorsconsidered in this method:1. Dr2. Relative flexibility of pile:
Flexibility no. = H4
/ EI(H is H+D)
3. Stabilit no. for cohesive soils:
Any section plotting above the
. .S = 1.25 c /eh
4. Relative height of piling , (H/ D+H)97.5/(997/12)=1.17 0.96 0.76
dense curve would besufficient for stress. PZ27 isadequate (allowable design
Dense Curve
, .
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From Rowes Moment Reduction Curve
Details of a Typical Anchor wall
Anchored Sheet Pile Wall:
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(Foundation Handbook-Winterkorn/Fang)
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Details of a Typical Anchor wallAnchored Sheet Pile Wall:
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(Foundation Handbook-Winterkorn/Fang)
Sheet Pile Anchorage:
Tie-back can be supported by deadman anchor, braced piles, cast-in-place tie rod,an e ca anc ors
Wales placed horizontally in front of
sheet piling.
Deadman Anchor
Cast-in-place
Braced Piles
ea man
16Cast-in-placeanchored tie-rod Helical Anchors
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Continuous Anchor Wall
Anchored Sheet Pile Wall:
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Resistance of Discontinuous Anchor (deadman)
Anchored Sheet Pile Wall:
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Grouted Anchors
Anchored Sheet Pile Wall:
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Sheet Pile Anchorage:
Load Capacity of Deadman Anchor:
Tu = Rp - Ra
pprox ma e a owa ecapacity of a givendeadman anchor inranular soil er unit
length of deadman:
21 dKAFS
Tpa
LF = (Pp Pa) L / FS
where FS = 1.25 1.5
A = 0.6d = depth of bottom
of deadman
Or:
Pp
Pa
Sheet Pile Anchorage:
=Auger hole
ressure grou anc or nsoil or rock
a
Ca = (0.7 0.9) c
K = Ko if grout is placed
z1
d
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under pressure or KaotherwiseL
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Sheet Pile Anchorage:Location of Anchor Plates
: anc or orce e erm ne rom x =Reduce it by a FSa = 2Determine dz to bottom of plate by F = 0at the deadman:
1aapz
2
az
FSFd
'
2
ap
The anchor plate must be located outside of the active slip plane (avoiding theinteraction of wall active zone and plate passive zone):
2
452
45 tantan ozo
oa ddHL
Calculate spacing of anchors s: longitudinal spacing, ha height of anchor plate.= x
ap
a
az KK
FSF
Lds
2
'2
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,required section modulus of the wall.
Proof testing setup andinstrumentation for threadbar
Sheet Pile Anchorage:
ground anchor
z1
Auger holeF = cadL + dz1LK tan
d
L
a = . . c
K = Ko if grout is placed
Under pressure or Ka
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Dunnicliff(1988)
o erw se
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Typical Steel Work Design
Anchored Sheet Pile Wall:
23(Foundation Handbook-Winterkorn/Fang)
Typical Steel Work Design
Anchored Sheet Pile Wall:
24(Foundation Handbook-Winterkorn/Fang)
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Typical Steel Work Design
Anchored Sheet Pile Wall:
25(Foundation Handbook-Winterkorn/Fang)