OVERVIEW REVIEW OF FOUNDATIONS & SOILS ENG.

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1 Soil Borings CAPSTONE DESIGN OVERVIEW REVIEW OF FOUNDATIONS & SOILS ENG. Geotechnical Report (not covered). Bearing Pressure Calculations. Settlement Calculations. Lateral Earth Pressure Calculations. Retaining Wall Design Review. Slide 1 of 43

2 OVERVIEW: BORINGS Slide 2 of 43

STANDARD PENETRATION TEST (SPT) (ASTM D1586-11) Marking of 6 inch Increments for SPT Test Photograph courtesy of physics.uwstout.edu Very common test worldwide 1902 - Colonel Gow of Raymond Pile Co.

3 STANDARD PENETRATION TEST (SPT) (ASTM D ) Marking of 6 inch Increments for SPT Test Photograph courtesy of physics.uwstout.edu Very common test worldwide Colonel Gow of Raymond Pile Co. Split-barrel sample driven in borehole. Conducted on 2½ to 5 ft depth intervals ASTM D1586 guidelines Drop Hammer (140 lbs falling 30 inches) 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 last two increments = SPT N value" (blows/ft) Correlations available with all types of soil engineering properties Disturbed Soil Samples Collected Text modified from FHWA NHI Course Subsurface Investigations Slide 3 of 43

STANDARD PENETRATION TEST (SPT) (ASTM D1586-11) Split Spoon Dimensions (after ASTM D1586) Typical Setup

4 STANDARD PENETRATION TEST (SPT) (ASTM D ) Split Spoon Dimensions (after ASTM D1586) Typical Setup Figures courtesy of J. David Rogers, Ph.D., P.E., University of Missouri-Rolla & FHWA NHI Course Slide 4 of 43

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

5 STANDARD PENETRATION TEST (SPT) (ASTM D ) Figure courtesy of FHWA NHI Course Subsurface Investigations Slide 5 of 43

6 STANDARD PENETRATION TEST (SPT) (ASTM D ) Figure courtesy of Slide 6 of 43

7 STANDARD PENETRATION TEST (SPT) Factors Affecting SPT (after Kulhawy & Mayne, 1990 & Table 8. FHWA IF ) Cause Inadequate Cleaning of Borehole Effects SPT not made in insitu soil, soil trapped, recovery reduced Influence on N Value Increases 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 7 of 43

Should be protected from extreme conditions (heat, freezing, drying). Sealed to minimize moisture loss.

8 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 Subsurface Investigations Slide 8 of 43

9 c u = undrained strength T = unit weight I R = rigidity index ' = friction angle OCR = overconsolidation K 0 = lateral stress state e o = void ratio V s = shear wave E' = Young's modulus C c = compression index q b = pile end bearing f s = pile skin friction k = permeability q a = bearing stress CAPSTONE DESIGN STANDARD PENETRATION TEST (SPT) CLAY N SAND D R = relative density T = unit weight LI = liquefaction index ' = friction angle c' = cohesion intercept e o = void ratio q a = bearing capacity p ' = preconsolidation V s = shear wave E' = Young's modulus = dilatancy angle q b = pile end bearing f s = pile skin friction What Do We Need? How Do We Get It? Courtesy of FHWA NHI Course Subsurface Investigations Slide 9 of 43

10 CAPSTONE DESIGN CORRECTIONS TO SPT N VALUE N measured = Raw SPT Value from Field Test (ASTM D ) N 60 = Corrected N values corresponding to 60% Energy Efficiency (i.e. The Energy Ratio (ER) = 60% (ASTM D ) SPT Corrections (From Table 9, FHWA IF ) Note: 30% < ER < 100% with average ER = 60% in the U.S. N 60 = C E C B C S C R N measured Factor Term Equipment Variable Correction Energy Ratio C E = ER/60 Donut Hammer Safety Hammer Automatic Hammer Borehole Diameter C B 150 mm mm 200 mm Standard Sampler Sampling Method C S Non-Standard Sampler Rod Length C R 3 4 m 4 6 m 6 10 m > 10 m For Guidance Only. Actual ER values should be measured per ASTM D to to to to Slide 10 of 43

11 CORRECTIONS TO SPT N VALUE TWO BORINGS/ONE SITE EXAMPLE: Measured N-values Corrected N Depth (meters) ER = 34 (energy ratio) Donut Saf ety 69 Sequence Depth (meters) Donut 6 Safety Trend Data from Robertson, et al. (1983), Courtesy of FHWA NHI Course Subsurface Investigations Slide 11 of 43

12 NORMALIZED SPT N VALUE (N 1 ) 60 (N 1 ) 60 = N 60 values normalized to 1 atmosphere overburden stress. (N 1 ) 60 = C N N 60 Where: C N = (P a /' vo ) n P a = 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 12 of 43

13 EFFECTIVE FRICTION ANGLE (') FOR SANDS - SPT 55 Triaxial Database from Frozen Sand Samples Friction Angle, ' (deg) ' = [15.4(N 1 ) 60 ] Sand (SP and SP-SM) Sand Fill (SP to SM) SM (Piedmont) H&T (1996) Normalized (N 1 ) 60 Figure FHWA NHI Course Subsurface Investigations Slide 13 of 43

14 SOIL SHEAR STRENGTH CORRELATIONS FROM IN-SITU TESTING Shear Strength Parameter Insitu Testing Method SPT CPT DMT Effective Soil Friction Angle ( ) See Slide 15 arctan[ log(q t / vo )] log(k D )-2.1 log 2 K D See Slide 15 Robertson and Campanella (1983) Marchetti et al. (2001) ISSMGE TC 16 Report Undrained Shear Strength (S u ) NO ACCEPTABLE CORRELATIONS (q t - vo )/N kt (N kt = 15 for CHS) Aas et al. (1986) 0.22 vo (0.5K D ) 1.25 Marchetti et al. (2001) ISSMGE TC 16 Report NOTES: 1. (N 1 ) 60 = N 60 (P a / vo ) 0.5 for sands. P a = 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. Slide 14 of 43

15 SOIL SHEAR STRENGTH CORRELATIONS FROM IN-SITU TESTING Effective Soil Friction Angle ( ) Summary from NCHRP Report 651 (2010) Equation ' = *exp( (N 1 ) 60 ) Reference Peck, Hanson, & Thorton (1974) from Kulhawy & Mayne (1990) ' = [20*(N 1 ) 60 ] for 3.5 (N 1 ) ' = *(N 1 ) (N 1 ) 2 60 ' = [15.4(N 1 ) 60 ] ' = [15(N 1 ) 60 ] for (N 1 ) 60 > 5 and 45 Hatanaka & Uchida (1996) Peck, Hanson, & Thorton (1974) from Wolff (1989) Mayne et a. (2001) based on Hatanaka & Uchida (1996) JRA (1996) Slide 15 of 43

16 SOIL ENGINEERING PROPERTY CORRELATIONS FROM IN-SITU TESTING (TABLE 1) Soil Density/Consistency N q t (MPa) t (pcf) V. Loose <30 Loose ( ) SANDS Medium Dense Dense Very Dense >50 > Very Soft COHESIVE SOILS Firm Stiff Very Stiff Hard >30 > after Fang et al. (1991) and EM NOTE: 1 MPa = tsf NA Slide 16 of 43

17 NORMALIZED SPT N VALUE N1 60 (AASHTO 2010) N1 60 = C N N 60 Where: C N = [0.77log10(40/' vo )] (C N < 2.0) ' vo = Insitu Vertical Effective Stress (ksf) N 60 = SPT Blow Count corrected for hammer eff. Table N1 60 vs. f (after Bowles, 1977). N1 60 f ( ) < * Assume ER = 60% (Cathead) & 80% (Automatic) Slide 17 of 43

AASHTO (2010) 10.6 SPREAD FOOTINGS 10.6.1.3 Effective Footing Dimensions B = B 2e b L = L 2e L Where: e b = Eccentricity parallel to Dimension B.

18 AASHTO (2010) 10.6 SPREAD FOOTINGS Effective Footing Dimensions B = B 2e b L = L 2e L Where: e b = Eccentricity parallel to Dimension B. e L = Eccentricity parallel to Dimension L. Figure C Reduced Footing Dimensions. Slide 18 of 43

19 AASHTO (2010) 10.6 SPREAD FOOTINGS Bearing Resistance of Soil q R = φ b q n Where: q R = Factored Resistance φ b = Resistance Factor (see Article ) q n = Nominal Bearing Resistance = q ult in Slide 19 of 43

20 REVIEW BEARING CAPACITY EQUATION (after Meyerhof, 1963) q u = c'n c F cs F cd F ci + qn q F qs F qd F qi + 0.5BN F s F d F i Cohesion Component Where: c' = Soil Cohesion N c = Bearing Capacity Factor - Cohesion q = Surcharge = D f N q = Bearing Capacity Factor - Surcharge = Soil Unit Weight N = Bearing Capacity Factor Soil F cs, F qs, F s = Shape Factors F cd, F qd, F d = Depth Factors F ci, F qi, F i = Inclination Factors Soil Component Soil Below Footing Surcharge Component Soil Above Footing B = Footing Width Slide 20 of 43

21 BEARING CAPACITY FACTORS (Dimensionless, based on ') N q N c N q N tan cot N 1tan 2 q e 2 tan Bearing Capacity Factor (Nc, Nq, N) N q N c N c N q N Also see Table 12.1, Das FGE (2006) for Tabular Data 1 N Effective Friction Angle (') ( ) 1 Slide 21 of 43

22 BEARING CAPACITY FACTORS (Table 12.1 Das FGE 2006) Slide 22 of 43

23 BEARING CAPACITY FACTORS Factor Cohesion Surcharge Unit Weight Shape (De Beer, 1970) Depth (D f /B 1) (Hanson, 1970) Depth (D f /B >1) (Hanson, 1970) Inclination Hanna & Meyerhof (1981) F F q B cs 1 B N B F qs 1 tan F L N s c L L F cd 1 0. cd 4 F ci tan 1 D f B 1 90 D f B 2 F F qd qd 1 2 tan 1 sin 1 2 tan F qi D 1 f 1 sin 2 tan B D f B F d F d F i = Inclination of Load with respect to vertical The factor tan -1 (D f /B) is in radians Slide 23 of 43

24 BEARING CAPACITY EQUATION (AASHTO LRFD Design Specifications, 5 th Ed., 2010) q n = cn cm + D f N qm C wq + 0.5BN m C w Cohesion Component Where: c = Undrained Shear Strength N cm = N c s c i c N c = Cohesion BCF for undrained loading (see Table a-1) s c = Footing Shape Correction Factor (see Table a-3) i c = Load Inclination Factor (Eq a-5 or 6) This is Munfakh et al. (2001) for determining φ b Surcharge Component Soil Above Footing = Moist Unit Weight of soil above footing D f = Footing Embedment Depth N qm = N q s q d q i q N q = Surcharge BCF (see Table a-1) s q = Footing Shape Correction Factor (see Table a-3) d q = Depth Correction Factor (see Table a-4) i q = Load Inclination Factor (Eq a-7) C wq = Groundwater CF (Table a-2) Soil Component Soil Below Footing = Moist Unit Weight of soil below footing B = Footing Width N m = N s i N = Unit Weight BCF (see Table a-1) s = Footing Shape Correction Factor (see Table a-3) i = Load Inclination Factor (Eq a-8) C w = Groundwater CF (Table a-2) Slide 24 of 43

25 CAPSTONE DESIGN PRESUMPTIVE MAXIMUM ALLOWABLE BEARING PRESSURES (from Table , IBC 2006) Material USCS q all (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 Clay, Sandy Clay, Silty Clay, Clayey Silt, Silt, and Sandy Silt Mud, Organic Silt, Organic Clays, Peat, and Unprepared Fill SW, SP, SM, SC, GM, GC CL, CH, ML, MH 1.5 See also Table 1 NAVFAC DM7.02 (p. 142) and Table C AASHTO (2010). 2 TBD Slide 25 of 43

2b-1. Punching Failure (Reduction in Shear Strength) Figure C10.6.1.3.

26 AASHTO (2010) 10.6 SPREAD FOOTINGS Other Bearing Capacity Considerations Figure C b-1. Punching Failure (Reduction in Shear Strength) Figure C c-1 (& c-2). Footing on Slopes (Reduction in Bearing Factors) Figure C e-2. Footing on Two Layer Soil Systems (Dependent). Slide 26 of 43

27 AASHTO (2010) 10.6 SPREAD FOOTINGS Settlement Analysis S S S S t e c s Where: S t = Total Settlement S e = Elastic Settlement S p = Primary Consolidation Settlement S s = Secondary Consolidation Settlement Slide 27 of 43

28 AASHTO (2010) 10.6 SPREAD FOOTINGS Settlement (Cohesionless Soils) Elastic Half-Space Method: Where: S q o(1 2 ) e 144E s z A S e = Elastic Settlement q o = Applied Vertical Stress (ksf) A = Effective Area of Footing (ft 2 ) E s = Young s Modulus of Soil (ksi) (See Article if direct measurements are not available) = Soil Poisson s Ratio (See Article if direct measurements are not available) z = Shape Factor (dimensionless) (As specified in Table ) Unless E s varies significantly with depth, E s 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 E s should be used. Slide 28 of 43

29 ELASTIC SETTLEMENT OF SOIL (DMT) Uses Direct Measurement of Soil to Calculate Settlement Figure courtesy of Marchetti (1999) - The Flat Dilatometer (DMT) and It's Applications to Geotechnical Design Slide 29 of 43

30 ELASTIC SETTLEMENT OF SOIL (DMT) S e M DMT Z Stress Distribution Where: S e = Elastic Settlement = Change in Stress M DMT = Constrained Modulus Z = Depth Figure courtesy of Marchetti (1999) - The Flat Dilatometer (DMT) and It's Applications to Geotechnical Design Slide 30 of 43

31 LATERAL EARTH PRESSURES COULOMB OR RANKINE REVIEW 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 ' > ' /2). Decreased accuracy w/ depth. Calculates lower active earth pressure than Rankine for level backslope. 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. Slide 31 of 43

32 CAPSTONE DESIGN LATERAL EARTH PRESSURES COULOMB OR RANKINE REVIEW Coulomb Rankine 1 sin Ka 1 sin K K K K a p p p tan tan 1 K a 2 2 (45 / 1 sin 1 sin (45 / 2) 2) Slide 32 of 43

33 LATERAL EARTH PRESSURES COULOMB OR RANKINE? Figure C Application of (a) Rankine and (b) Coulumb Earth Pressure Theories in Retaining Wall Design (AASHTO 2012). Slide 33 of 43

Overall Stability (Service) Figure 13.4.

34 REVIEW: RETAINING WALL DESIGN ANALYSES Overturning Sliding (Strength) Bearing Capacity (Strength) Overall Stability (Service) Figure Das FGE (2005) and Figure C (AASHTO 2012). Slide 34 of 43

35 AASHTO (2010) SECTION 11 ABUTMENTS 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 ( ) Slide 35 of 43

36 AASHTO (2010) SECTION 11 ABUTMENTS Strength Limit States Abutments and walls shall be investigated at the strength limit states using Eq 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 36 of 43

37 AASHTO (2010) SECTION 11 ABUTMENTS Load Combinations & Load Factors 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 Figure C Typical Application of Load Factors for Sliding and Eccentricity. Slide 37 of 43

38 AASHTO (2010) SECTION 11 ABUTMENTS Load Combinations & Load Factors 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 Figure C Typical Application of Load Factors for Sliding and Eccentricity. Slide 38 of 43

39 AASHTO (2010) 11 ABUTMENTS Load Combinations & Load Factors Where: LS = Live Load Surcharge Figure C Typical Application of Live Load Surcharge. Slide 39 of 43

40 AASHTO (2010) SECTION 11 ABUTMENTS BEARING RESISTANCE (SOIL) v V B 2e Where: V = Sum of Vertical Forces B = Footing Width e = Eccentricity Figure Bearing Stress Criteria for Conventional Wall Foundations on Soil. Slide 40 of 43

41 AASHTO (2010) SECTION 11 ABUTMENTS Sliding (refer to Failure by Sliding) R R = φr n = φ R + φ ep R ep Where: R R = Factored Resistance against Failure by Sliding R n = Nominal Sliding Resistance φ = Shear Resistance Factor (see Table ) R = Nominal Shear Resistance (=V*tan) φ ep = Passive Resistance Factor (see Table ) R ep = Nominal Passive Resistance Slide 41 of 43

42 AASHTO (2010) SECTION 11 ABUTMENTS Passive Resistance Neglected in Stability Calculations Unless base of the wall extends below the depth of maximum scour, freeze-thaw, or other disturbances Neglected is soil providing passive resistance is, or is likely to become, soft, loose, or disturbed, or if contact between the soil and ground is not tight. Slide 42 of 43

INTERFACIAL FRICTION ANGLES (NAVFAC DM7.02) NOTE: ⅓' ' < ⅔' 14.485 CAPSTONE DESIGN Section 10.6.3.

43 INTERFACIAL FRICTION ANGLES (NAVFAC DM7.02) NOTE: ⅓' ' < ⅔' CAPSTONE DESIGN Section : Concrete Cast against Soil: tan = tan f Precast Concrete Footing: tan = 0.8*tan f Slide 43 of 43

CIVE.4850 CAPSTONE DESIGN Module 3 Geotechnical Engineering 2016 F.E. EXAM. Slide 1 of 59. Revised 02/2016

CIVE.4850 CAPSTONE DESIGN Module 3 Geotechnical Engineering 2016 F.E. EXAM. Slide 1 of 59. Revised 02/2016 2016 F.E. EXAM Slide 1 of 59 2016 F.E. EXAM 8-13% GEOL.3250 (optional) CIVE.3300 & CIVE.3330 CIVE.4310 Slide 2 of 59 CIVE.4850 CAPSTONE DESIGN 2016 FUNDAMENTALS OF ENGINEERING (FE) EXAM CALCULATOR POLICY