CIVE.4850 2018 Capstone Geotechnical...

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Slide 1 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

2018 F.E. EXAM

Slide 2 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

2018 F.E. EXAM

8-13%

CIVE.3300 & CIVE.3330

CIVE.4310

GEOL.3250

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

2018 FUNDAMENTALS OF ENGINEERING (FE) EXAM CALCULATOR POLICY (as of 02/20/18)

http://ncees.org/exams/calculator

Casio: All fx-115 models and fx-991 models (Any Casio calculator must have “fx-115” or “fx-991” in its model name.)

Hewlett Packard: The HP 33s and HP 35s models, but no others.

Texas Instruments: All TI-30X and TI-36X models (Any Texas Instruments calculator must have “TI-30X” or “TI-36X” in its model name.)

CasioFX-115MSPlus

HPHP 33s

TITI-36X SOLAR

Slide 4 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

• Soil Borings.

• Geotechnical Report (not covered).

• Bearing Pressure Calculations.

• Settlement Calculations.

• Lateral Earth Pressure Calculations.

• Retaining Wall Design Review.

OVERVIEWREVIEW OF CIVE.4310 FOUNDATION & SOILS ENG.

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

OVERVIEW: BORINGS

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

OVERVIEW: BORINGS

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

OVERVIEW: BORINGSShows the following:• Soil Profile (determined

from sampling and boring information) with respect to depth and/or elevation.

• Groundwater Table (GWT).

• SPT N Values.• Laboratory Test Results (if

available).

ASTM D5434-12 Standard Guide for Field Logging of Subsurface Explorations of Soil and Rock

Slide 8 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

• Very common test worldwide• 1902 – Col. Gow of Raymond Pile Co.• Split-barrel sample driven in

borehole.• Conducted on 2½ to 5 ft intervals• ASTM D1586 guidelines• Drop Hammer (140 lbs falling 30 in.)• 3 or 4 increments of 6 inches each

– Three (3) Increments: Sum of last two increments = “SPT N value" (blows/ft)

– Four (4) Increments: Sum of middle two increments = “SPT N value" (blows/ft)

• Correlations available with all types of soil engineering properties

• Disturbed Soil Samples Collected

STANDARD PENETRATION TEST (SPT) (ASTM D1586-11)

Text modified from FHWA NHI Course 132031 Subsurface Investigations

Marking of 6 inch Increments for SPT Test

Photograph courtesy of physics.uwstout.edu

Slide 9 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Figures courtesy of J. David Rogers, Ph.D., P.E., University of Missouri-Rolla & FHWA NHI Course 132031

Typical Setup

Split Spoon Dimensions (after ASTM D1586)

STANDARD PENETRATION TEST (SPT) (ASTM D1586-11)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Figure courtesy of FHWA NHI Course 132031 Subsurface Investigations

STANDARD PENETRATION TEST (SPT) (ASTM D1586-11)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Figure courtesy of http://www.civil.ubc.ca

STANDARD PENETRATION TEST (SPT) (ASTM D1586-11)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

STANDARD PENETRATION TEST (SPT)Factors Affecting SPT (after Kulhawy & Mayne, 1990 & Table 8. FHWA IF-02-034 )

Cause EffectsInfluence

on N Value

Inadequate Cleaning of BoreholeSPT not made in insitu soil, soil

trapped, recovery reducedIncreases

Failure to Maintain Adequate Head in Borehole Bottom of borehole may become quick Decreases

Careless Measure of Drop Hammer Energy varies Increases

Hammer Weight Inaccurate Hammer Energy varies Inc. or Dec.

Hammer Strikes Drill Rod Collar Eccentrically Hammer Energy reduced Increases

Lack of Hammer Free (ungreased sleeves, stiff rope, more than 2 turns on cathead, incomplete release of drop, etc.)

Hammer Energy reduced Increases

Sampler Driven Above Bottom of Casing Sampler driven in disturbed soil Inc. Greatly

Careless Blow Count Recording Inaccurate Results Inc. or Dec.

Use of Non-Standard Sampler Correlations with Std. Sampler Invalid Inc. or Dec.

Coarse Gravel or Cobbles in soil Sampler becomes clogged or impeded Increases

Use of Bent Drill Rods Inhibited transfer of energy to sampler Increases

Slide 13 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

CARE & PRESERVATION OF SOIL SAMPLES

• Mark and Log samples upon retrieval (ID, type, number, depth, recovery, soil, moisture).

• Place jar samples in wood or cardboard box.

• Should be protected from extreme conditions (heat, freezing, drying).

• Sealed to minimize moisture loss.

• Packed and protected against excessive vibrations and shock.

Text and Figures courtesy of FHWA NHI Course 132031 Subsurface Investigations

Slide 14 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

N

DR = relative densitygT = unit weightLI = liquefaction index' = friction anglec' = cohesion intercepteo = void ratioqa = bearing capacityp' = preconsolidationVs = shear waveE' = Young's modulus = dilatancy angleqb = pile end bearingfs = pile skin frictionSAND

cu = undrained strengthgT = unit weightIR = rigidity index' = friction angleOCR = overconsolidationK0 = lateral stress stateeo = void ratioVs = shear waveE' = Young's modulusCc = compression indexqb = pile end bearingfs = pile skin frictionk = permeabilityqa = bearing stress

CLAY

Courtesy of FHWA NHI Course 132031 Subsurface Investigations

What Do We Need? How Do We Get It?

STANDARD PENETRATION TEST (SPT)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

CORRECTIONS TO SPT N VALUENmeasured = Raw SPT Value from Field Test (ASTM D1586-11)

N60 = Corrected N values corresponding to 60% Energy Efficiency

(i.e. The Energy Ratio (ER) = 60% (ASTM D4633-10)Note: 30% < ER < 100% with average ER = 60% in the U.S.

Factor Term Equipment Variable Correction

Energy Ratio CE = ER/60

Donut Hammer

Safety Hammer

Automatic Hammer

0.5 to 1.0

0.7 to 1.2

0.8 to 1.5

Borehole Diameter CB

65 – 155 mm

150 mm

200 mm

1.00

1.05

1.15

Sampling Method CS

Standard Sampler

Non-Standard Sampler

1.0

1.1 to 1.3

Rod Length CR

3 – 4 m

4 – 6 m

6 – 10 m

> 10 m

0.75

0.85

0.95

1.00

N60 = CECBCSCRNmeasured

For Guidance Only. Actual ER values should be measured per ASTM D4633

SPT Corrections(From Table 9,

FHWA IF-02-034)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

4

6

8

10

12

14

16

0 10 20 30 40 50

Measured N-values

De

pth

(m

ete

rs)

Donut

Safety

Sequence

ER = 34 (energy ratio)

45

40

41

41

39

47

56

55

60

56

63

63

63

64

69

4

6

8

10

12

14

16

0 10 20 30 40 50

Corrected N60

Dep

th (

met

ers

)

Donut

Safety

Trend

CORRECTIONS TO SPT N VALUE

TWO BORINGS/ONE SITE EXAMPLE:

Data from Robertson, et al. (1983), Courtesy of FHWA NHI Course 132031 Subsurface Investigations

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

NORMALIZED SPT N VALUE (N1)60(N1)60 = N60 values normalized to 1 atmosphere overburden stress.

(N1)60 = CNN60

Where:CN = (Pa/'vo)n

Pa = Atmospheric Pressure (1 atm=14.7 psi=2116 psf)'vo = Insitu Vertical Effective Stress

n = 1 (clays) and 0.5 to 0.6 (sands)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Triaxial Database from Frozen Sand Samples

20

25

30

35

40

45

50

55

0 10 20 30 40 50 60

Normalized (N1)60

Frict

ion

Ang

le,

' (d

eg)

Sand (SP and SP-SM)

Sand Fill (SP to SM)

SM (Piedmont)

H&T (1996)

' = [15.4(N1)60]0.5+20

EFFECTIVE FRICTION ANGLE (') FOR SANDS - SPT

Figure 9-12. FHWA NHI Course 132031 Subsurface Investigations

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

SOIL SHEAR STRENGTH CORRELATIONS

FROM IN-SITU TESTINGShear

Strength Parameter

Insitu Testing Method

SPT CPT DMT

Effective Soil Friction

Angle (′)

See Slide 20 arctan[0.1+0.38log(qt/′vo)] 28°+14.6°log(KD)-2.1°log2KD

See Slide 20Robertson and Campanella

(1983)Marchetti et al. (2001)ISSMGE TC 16 Report

Undrained Shear

Strength (Su)

NO ACCEPTABLE CORRELATIONS

(qt-vo)/Nkt(Nkt = 15 for CHS)

0.22′vo(0.5KD)1.25

Aas et al. (1986)Marchetti et al. (2001)ISSMGE TC 16 Report

NOTES:1. (N1)60 = N60(Pa/′vo)

0.5 for sands. Pa = Atmospheric Pressure = 1 bar ≈ 1 tsf.2. ′vo = Insitu Effective Overburden Pressure = Insitu Vertical Effective Stress.3. vo = Total Overburden Pressure = Insitu Vertical Total Stress.

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Equation Reference

' = 54° - 27.6034*exp(-0.014(N1)60)

Peck, Hanson, & Thorton (1974) from Kulhawy & Mayne (1990)

' = [20*(N1)60]0.5 + 20°for 3.5 (N1)60 30

Hatanaka & Uchida (1996)

' = 27.1° +0.3*(N1)60 –0.00054(N1)2

60

Peck, Hanson, & Thorton (1974)

from Wolff (1989)

' = [15.4(N1)60]0.5 + 20°

Mayne et a. (2001) based on

Hatanaka & Uchida (1996)

' = [15(N1)60]0.5 + 15°for (N1)60 > 5 and 45°

JRA (1996)

Effective Soil Friction Angle (′) Summary from NCHRP Report 651 (2010)

SOIL SHEAR STRENGTH CORRELATIONS

FROM IN-SITU TESTING

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

after Fang et al. (1991) and EM 1110-1-1905.NOTE: 1 MPa = 10.44 tsf

Soil Density/Consistency Nqt

(MPa)gt

(pcf)′(°)

SANDS

V. Loose 0-4 0-2 90-105 <30

Loose 5-10 2-5 95-110 30-35

Medium Dense 11-30 5-15 105-120 35-38

Dense 31-50 15-25 115-130 38-41

Very Dense >50 >25 125-140 41-44

COHESIVE SOILS

Very Soft 0-2 0-0.5 90-100

NA

Firm 2-8 0.5-1.5 90-110

Stiff 9-15 1.5-3 105-125

Very Stiff 15-30 3-6 115-135

Hard >30 >6 120-140

SOIL ENGINEERING PROPERTY CORRELATIONS

FROM IN-SITU TESTING

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

N160 = CNN60

Where:CN = [0.77log10(40/'vo)](CN < 2.0)

'vo = Insitu Vertical Effective Stress (ksf)

N60 = Corrected SPT Blow Count = (ER/60%)N

N160 f (°)

<4 25-30

4 27-32

10 30-35

30 35-40

50 38-43

Table 10.4.6.2.4-1. N160 vs. f

(after Bowles, 1977).

* Assume ER = 60% (Cathead) & 80% (Automatic)

NORMALIZED SPT N VALUE N160(AASHTO 2012)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) 10.6 – SPREAD FOOTINGS10.6.1.3 – Effective Footing Dimensions

Figure C10.6.1.3.1. – Reduced Footing Dimensions.

B′ = B – 2eb

L′ = L – 2eL

Where:eb = Eccentricity parallel to

Dimension B.eL = Eccentricity parallel to

Dimension L.

Slide 24 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) 10.6 – SPREAD FOOTINGS10.6.3.1 – Bearing Resistance of Soil

R b nWhere:

qR = Factored Resistanceφb = Resistance Factor

(see Article 10.5.5.2.2)qn = Nominal Bearing Resistance

= qult in CIVE.4310

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

REVIEW – BEARING CAPACITY EQUATION(after Meyerhof, 1963)

qu = c'NcFcsFcdFci + qNqFqsFqdFqi + 0.5gBNgFgsFgdFgi

CohesionComponent

Surcharge ComponentSoil Above Footing

Soil ComponentSoil BelowFooting

Where:c' = Soil Cohesion Nc = Bearing Capacity Factor - Cohesionq = Surcharge = Dfg Nq = Bearing Capacity Factor - Surchargeg = Soil Unit Weight Ng = Bearing Capacity Factor – Soil B = Footing WidthFcs, Fqs, Fgs = Shape FactorsFcd, Fqd, Fgd = Depth FactorsFci, Fqi, Fgi = Inclination Factors

Slide 26 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

BEARING CAPACITY

FACTORS(Dimensionless, based on ')

0 5 10 15 20 25 30 35 40 45

Effective Friction Angle (') (°)

1

10

100

2

4

6

8

20

40

60

80

Be

ari

ng

Ca

pa

cit

y F

act

or

(Nc

, Nq

, Ng)

0 5 10 15 20 25 30 35 40 45

1

10

100

2

4

6

8

20

40

60

80

Nc

Nq

Ng

Nc

Nq

Ng

cot1qc NN

g tan12 qNN

tan2

245tan eNq

Also see Table 12.1, Das FGE (2006) forTabular Data

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

BEARING CAPACITY FACTORS (Table 12.1 Das FGE 2006)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

BEARING CAPACITY FACTORS

(Table 10.6.3.1.2a-1, AASHTO 2012)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Factor Cohesion Surcharge Unit Weight

Shape(De Beer, 1970)

Depth(Df/B ≤1)

(Hanson, 1970)

Depth(Df/B >1)

(Hanson, 1970)

InclinationHanna &

Meyerhof (1981)

= Inclination of Load with respect to verticalThe factor tan-1(Df/B) is in radians

B

DF fqd

12 tansin1tan21

B

DF fcd 4.01

g 1iF

1dFg

tan1L

BFqs

c

qcs N

N

L

BF 1

L

BF s 4.01g

B

DF fcd

1tan4.01

B

DF fqd

2sin1tan21

2

901

qiF

1dFg

2

901

ciF

BEARING CAPACITY FACTORS

Slide 30 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

BEARING CAPACITY EQUATION(Sec. 10.6.3.1.2, AASHTO LRFD Design Specifications, 2012)

qn = cNcm + gDfNqmCwq + 0.5gBNgmCwgCohesionComponent

Surcharge ComponentSoil Above Footing

Soil ComponentSoil BelowFootingWhere:

c = Undrained Shear StrengthNcm = NcscicNc = Cohesion BCF for

undrained loading (see Table 10.6.3.1.2a-1)

sc = Footing Shape Correction Factor (see Table 10.6.3.1.2a-3)

ic = Load Inclination Factor (Eq. 10.6.3.1.2a-5 or 6)

g = Moist Unit Weight of soil above footing

Df = Footing Embedment Depth

Nqm = NqsqdqiqNq = Surcharge BCF (see

Table 10.6.3.1.2a-1)sq = Footing Shape Correction

Factor (see Table 10.6.3.1.2a-3)

dq = Depth Correction Factor (see Table 10.6.3.1.2a-4)

iq = Load Inclination Factor (Eq. 10.6.3.1.2a-7)

Cwq = Groundwater CF (Table 10.6.3.1.2a-2)

g = Moist Unit Weight of soil below footing

B = Footing WidthNgm = NgsgigNg = Unit Weight BCF (see

Table 10.6.3.1.2a-1)sg = Footing Shape Correction

Factor (see Table 10.6.3.1.2a-3)

ig = Load Inclination Factor (Eq. 10.6.3.1.2a-8)

Cwg = Groundwater CF (Table 10.6.3.1.2a-2)This is Munfakh et al. (2001)

for determining qn

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Material USCS qall (ksf)

Crystalline Bedrock 12

Sedimentary and Foliated Rock 4

Sandy Gravel and/or Gravel GW & GP 3

Sand, Silty Sand, Clayey Sand, Silty Gravel, & Clayey Gravel

SW, SP, SM, SC, GM, GC

2

Clay, Sandy Clay, Silty Clay, Clayey Silt, Silt, and Sandy Silt

CL, CH, ML, MH 1.5

PRESUMPTIVE MAXIMUM ALLOWABLE BEARING PRESSURES(from Table 1806.2, IBC 2012)

See also Table 1 NAVFAC DM7.02 (p. 142) andTable C10.6.2.6.1-1 AASHTO (2012).

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

PRESUMPTIVE MAXIMUM ALLOWABLE BEARING PRESSURES(Table C10.6.2.6.1-1 AASHTO (2012) based on

Table 1 NAVFAC DM7.02 (p. 142))

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) 10.6 – SPREAD FOOTINGSOther Bearing Capacity Considerations

Figure C10.6.3.1.2b-1.Punching Failure

(Reduction in Shear Strength)Figure C10.6.3.1.2c-1 (& c-2).

Footing on Slopes(Reduction in Bearing Factors)

Figure C10.6.3.1.2e-2.Footing on Two Layer Soil

Systems (Dependent).

Slide 34 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

scet SSSSWhere:

St = Total SettlementSe = Elastic SettlementSp = Primary Consolidation SettlementSs = Secondary Consolidation Settlement

AASHTO (2012) 10.6 – SPREAD FOOTINGS10.6.2.4 – Settlement Analysis

Slide 35 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

zs

oe E

AqS

144

)1( 2

Where:

Se = Elastic Settlementqo = Applied Vertical Stress (ksf)A’ = Effective Area of Footing (ft2)Es = Young’s Modulus of Soil (ksi)

(See Article 10.4.6.3 if directmeasurements are not available)

Elastic Half-SpaceMethod:

= Soil Poisson’s Ratio(See Article 10.4.6.3 if directmeasurements are not available)

z = Shape Factor (dimensionless)(As specified in Table 10.6.2.4.2-1)

Unless Es varies significantly with depth, Es should be determined at a depth of about ½ to 2/3 of B below the footing. If the soil modulus varies significantly with depth, a weighted average value of Es should be used.

AASHTO (2012) 10.6 – SPREAD FOOTINGS10.6.2.4 – Settlement (Cohesionless Soils)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Figure courtesy of Marchetti (1999) - The Flat Dilatometer (DMT) andIt's Applications to Geotechnical Design

ELASTIC SETTLEMENT OF SOIL (DMT)

Uses Direct Measurement

of Soil to Calculate

Settlement

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

• Direct push of stainless steel plate at 20-cm intervals; No borings; no cuttings.

• Introduced by Marchetti(1980).

• 18o angled blade • Pneumatic inflation of flexible

steel membrane using nitrogen gas

• Two pressure readings taken (A and B) within about 1 minute.

FLAT PLATE DILATOMETER (DMT)(ASTM D6635-15)

• B

• A

Figures and Text courtesy of FHWA NHI Course 132031 Subsurface Investigations

Slide 38 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

FLAT PLATE DILATOMETER (DMT) (ASTM D6635-15)

Figure courtesy of FHWA NHI Course 132031 Subsurface Investigations

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Marchetti Device (ASCE JGE, March 1980; ASTM Geot. Testing J., June 1986)

FLAT PLATE DILATOMETER (DMT) (ASTM D6635-01(2007))Manual Reading System (Standard)

Figures courtesy of FHWA NHI Course 132031 Subsurface Investigations

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

FLAT PLATE DILATOMETER (DMT) (ASTM D6635-01(2007))Computerized System (Standard)

Figure courtesy of FHWA NHI Course 132031 Subsurface Investigations

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

• Calibrations: A, B (positive values)

• Readings: contact pressure "A" and expansion pressure "B" with depth

• Corrections for membrane stiffness in air: p0 = 1.05(A + A) - 0.05(B - DB)

p1 = B -B

• DMT INDICES:

• ID = material index = (p1-po)/(po-uo)

• ED = dilatometer modulus = 34.7(p1-po)

• KD = horizontal stress index

= (po-uo)/svo’

FLAT PLATE DILATOMETER (DMT) (ASTM D6635-15)

• B

• A

Text courtesy of FHWA NHI Course 132031 Subsurface Investigations

Slide 42 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

FLAT PLATE DILATOMETER (DMT) (ASTM D6635-15)Results – Charleston, SC Project

Soil BehaviorClassification

ED with Depth

Raw Data & Calibrations

DMT Results courtesy of WPC Engineering Inc.

Slide 43 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Also see Hajduk, E.L., Meng, J., Wright, W.B., and Zur, K.J. (2006). “DilatometerExperience in the Charleston, South Carolina Region”, 2nd International Conference onthe Flat Dilatometer, Washington, D.C.

SPT-CPT-DMT COMPARISON

From Local Project in

Charleston, SC Area (2000)

Slide 44 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

ZM

SDMT

e

Stress Distribution

Figure courtesy of Marchetti (1999) - The Flat Dilatometer (DMT) and It's Applications to Geotechnical Design

Where:

Se = Elastic Settlement = Change in StressMDMT = Constrained ModulusZ = Depth

ELASTIC SETTLEMENT OF SOIL (DMT)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

ELASTIC SETTLEMENT OF SOIL (DMT)

Figure from Hayes (1990)

Slide 46 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

LATERAL EARTH PRESSURES

COULOMB OR RANKINE REVIEW

Rankine “State of Stress” Theory:• Does not account for wall friction.• Requires vertical wall.• Conservative relative to other

methods.• Fixed plane of failure.• Favored by the transportation

agencies (AASHTO and FHWA) . See AASHTO Standard Specifications for Highway Bridges.

Coulomb “Wedge”Theory:• Accounts for wall friction.• Unique failure angle for each design.• Used by National Masonry Concrete

Association (NCMA) & USACE.• Inaccurate passive earth pressures

w/large wall angles or friction angle (particularly for d' > ' /2) .

• Decreased accuracy w/ depth.• Calculates lower active earth

pressure than Rankine for level backslope.

Slide 47 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

ap

p

p

a

a

KK

K

K

K

K

1

)2/45(tan

sin1

sin1

)2/45(tan

sin1

sin1

2

2

LATERAL EARTH PRESSURES

COULOMB OR RANKINE REVIEWRankineCoulomb

Slide 48 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

LATERAL EARTH

PRESSURES

COULOMB OR

RANKINE?

Figure C3.11.5.3-1 –Application of (a) Rankine

and (b) Coulumb Earth Pressure Theories in

Retaining Wall Design (AASHTO 2012).

Slide 49 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

REVIEW: RETAINING WALL DESIGN ANALYSES

Overturning Sliding(Strength)

Figure 13.4. Das FGE (2005) and Figure C11.6.2.3-1 (AASHTO 2012).

BearingCapacity(Strength)

Overall Stability(Service)

Slide 50 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) SECTION 11 – ABUTMENTS11.5.2 – Service Limit States

Abutments, piers, and wall shall be

investigated for:• Excessive vertical and lateral displacements

• Vertical: Dependent on wall

• Lateral: < 1.5 inches (C11.5.2)

• Overall Stability

• Can use Modified Bishop, Simplified Janbu, and

Spencer Analysis Methods (11.6.2.3)

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) SECTION 11 – ABUTMENTS11.5.3 – Strength Limit States

Abutments and walls shall be investigated at the strength limit states using Eq. 1.3.2.1-1 for:• Bearing Resistance Failure (i.e. bearing

capacity)• Lateral Sliding• Excessive Loss of Base Contact• Pullout Failure of anchors and soils

reinforcements• Structural Failure

Slide 52 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) SECTION 11 – ABUTMENTS11.5.5 – Load Combinations & Load Factors

Figure C11.5.6-2 – Typical Application of Load Factors for Sliding and Eccentricity.

Where:DC = Dead Load of Structural

Components

DW = Dead Load of Wearing

Surfaces and Utilities

EH = Horizontal Earth Pressure

Load

ES = Earth Surcharge Load

EV = Vertical Pressure from Dead

Load of Earth Fill

WA = Water Load and Stream

Pressure

Slide 53 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) SECTION 11 – ABUTMENTS11.5.5 – Load Combinations & Load Factors

Figure C11.5.6-2 – Typical Application of Load Factors for Sliding and Eccentricity.

Where:DC = Dead Load of Structural

Components

DW = Dead Load of Wearing

Surfaces and Utilities

EH = Horizontal Earth Pressure

Load

ES = Earth Surcharge Load

EV = Vertical Pressure from Dead

Load of Earth Fill

WA = Water Load and Stream

Pressure

Slide 54 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) 11 – ABUTMENTS11.5.5 – Load Combinations & Load Factors

Figure C11.5.6-3 – Typical Application of Live Load Surcharge.

Where:LS = Live Load Surcharge

Slide 55 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

Figure 11.6.3.2.-1 – Bearing Stress Criteria for Conventional Wall Foundations on Soil.

eB

Vv 2

AASHTO (2012) SECTION 11 –ABUTMENTS

11.6.3.2 – BEARING

RESISTANCE (SOIL)

Where:V = Sum of Vertical ForcesB = Footing Widthe = Eccentricity

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) SECTION 11 – ABUTMENTS11.6.3.6 – Sliding (refer to 10.6.3.4 – Failure by Sliding)

RR = φRn = φtRt + φepRepWhere:

RR = Factored Resistance against Failure by SlidingRn = Nominal Sliding Resistanceφt = Shear Resistance Factor (see Table 10.5.5.2.2-1)

Rt = Nominal Shear Resistance (=V*tand)φep = Passive Resistance Factor (see Table 10.5.5.2.2-1)

Rep = Nominal Passive Resistance

Slide 57 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

AASHTO (2012) SECTION 11 – ABUTMENTS

11.6.3.5 – Passive Resistance• Neglected in Stability Calculations

• Unless base of the wall extends below the

depth of maximum scour, freeze-thaw, or

other disturbances

• If soil providing passive resistance is, or

is likely to become, soft, loose, or

disturbed, or if contact between the soil

and wall is not tight.

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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

NOTE:⅓' <d' < ⅔'

INTERFACIAL FRICTION ANGLES(NAVFAC DM7.02)

Section 10.6.3.4:Concrete Cast against Soil:tan d = tan f

Precast Concrete Footing:tan d = 0.8*tan f

Slide 59 of 59Revised 02/2018

CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering

MODULE 3 TASKS

(REFER TO MODULE HANDOUT)• Using Boring B-2 (and assuming that

elevations begin at the ground surface for

the existing bridge), you will do the

following:

• Determine factored bearing capacity (qR)

• Compute applied vertical stress (qo) based

on 1 inch of settlement.