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CIVE.4850 CAPSTONE DESIGNModule 3 – Geotechnical Engineering
2018 F.E. EXAM
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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
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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
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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)
Slide 18 of 59Revised 02/2018
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.
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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
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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
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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
Slide 31 of 59Revised 02/2018
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).
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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
Slide 56 of 59Revised 02/2018
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.
Slide 58 of 59Revised 02/2018
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.