2014 Hoover Distinguished Lecture 38th ASCE IOWA SECTION GEOTECHNICAL CONFERENCE GeoCharacterization for Shallow and Deep Foundations Using Hybrid Geotechnical-Geophysical In-Situ Tests
Paul W. Mayne, PhD, P.E. Georgia Institute of Technology
10 April 2014 Purposes: Geotechnical Site Investigation . Required for all geotechnical projects . Determine geostratigraphy for site development . Information for foundation design . Data for geotechnical parameter evaluation . Input to analytical models and numerical FEM . Minimize problems during construction . Mitigate potential for legal involvement GeoCharacterization Quote from Lord Kelvin (1883): “...when you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind"
Jaksa (2005) GeoCharacterization in 2014 . This talk is part State-of-the-Art (SOA) = What we COULD be doing . This talk also part State-of-the-Practice (SOP) = What we ARE doing . Limited time, so focus on geocharacterization . Intro GeoCourse needs more balance of geophysics + in-situ + lab testing . This talk = part SOA + part SOP → betterment Mayne ≠ SOB Evolution of Geotechnical Site Characterization Modified after Lacasse (1985) 100 Probabilistic 90 Time period covered Models FEM by your favorite FD SPM Numerical 80 CSSM Simulation geotextbook Plasticity Analytical DEM 70 Elasticity Triaxial Models Therefore Missing HyperPlasticity 60 Cavity Plane Topics of Great Expansion Strain 50 ImportanceLaboratory to Resonant Bender Testing DSS Modern Geotechnical Column Elements 40 Permeameter Continuous Consolidometer SCPTu Education CRS Controlled VisCPT 30 Direct Shear Gradient SDMT Ball CPTu T-bar 20 Oedometer IBST SBPMT TSC HF RCPTu Resistivity 10 In-Situ Tests SCPTu EM SPT Erdbaumechanik DMT GPR Geophysics VST PMT Liquid Limit CPT SRF CHT DHT SASW MASW CSW ReMi Level offor Level Reliance (%) Design 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 Gow Atterberg Terzaghi Year Geotechnical Laboratory Testing Devices HC RCT Hyd Cup UC TTx PSC PSE Sieves Oed
Fall Consolidometers DSB Cone BE DSS CIUC CKoUC CKoUE CIUE Pp Tv wn CKoDE CIDE Permeameters Iso CIDC CKoDC RS Consol DSC Vst
Pan
Grain size analyses Mechanical oedometer Triaxial apparatus (iso-consols, Hydrometer Consolidometer CIUC, CKoUC, CAUC, CIUE, CAUE, Water content by oven Constant rate of shear (CRS) CKoUE, stress path, CIDC, CKoDC, Liquid limit cup Falling-head permeameter CIDE, CKoDE, constant P’) Constant-head permeameter Electron microscopy Plane strain apparatus (PSC, PSE) Plastic limit thread Flow permeameter True triaxial (cuboidal) Fall cone device Direct shear box Pocket penetrometer X-ray diffraction Hollow cylinder Torvane Ring shear Torsional Shear Unconfined compression Unconsolidated undrained Tx Resonant Column Test device Miniature vane Simple shear Non-resonant column Digital image analysis Directional shear cell Bender elements Methods for Geomaterial Characterization Soils Laboratory
Lab Rat Laboratory Soils Testing Varved Clay
Sampler A Sampler B Limited number (discrete points) Lengthy test durations Affected by sample disturbance Expensive: Cost per specimen: • Oedometer = $600 (2 weeks) • Automated Consolidation = $800 (2-3 days) • CIUC Triaxial = $600 (2 to 3 days)
• CK0UC Triaxial = $1500 ea (5 days) • Resonant Column= $2000 ea (1 week) • Permeability = $800 (1 to 2 weeks) Field In-Situ Geotechnical Test Methods SPT SPLT TSC Full Flow Penetrometers PMT SPTT TxPT MPT RapSochs LPT CPMT SWS RCPTu DMTà BPT VST PV PBPT SCPMTù HF PPT K0SB CPT TBPT CPTù DMT SCPTu PLT HPT FTS CPTu DEPPT BST SDMT
SPT = Standard Penetration Test TSC = Total Stress Cell (spade cell) PPT = Plate Penetration Test TxPT = Texas Penetration Test FTS = Freestand Torsional Shear PLT = plate load test VST = Vane Shear Test PV = Piezovane HPT = Helical Probe Test PMT = Pressuremeter Test MPT = Macintosh Probe Test PBPT = piezoball penetration test CPMT = Cone Pressuremeter CPT = Cone Penetration Test RapSochs = Rapid soil characterization system DMT = Dilatometer Test CPTu = Piezocone Penetration CPTù = piezodissipation test SPLT = Screw Plate Load Test RCPTu = Resistivity Piezocone DMTà = Dilatometer with A-reading dissipations ISB = Iowa K0 Stepped Blade SCPTu = Seismic Cone SPTT = Standard Penetration Test with Torque SWS = Swedish Weight Sounding SDMT = Seismic Flat Dilatometer LPT = Large Penetration Test HF = Hydraulic Fracture TBPT = T-Bar Penetrometer Test DEPPT = Dual Element PiezoProbe Test BST = Borehole Shear Test BPT = Ball Penetrometer SCPMTu = Seismic Piezocone Pressuremeter Geotechnical Methods for Site Investigation Soils Laboratory In-Situ Testing
Lab Rat Field Mouse
Ball penetrometer testing Home 1902 Office Appliances Equipment Telegraph Stove Casagrande Cup Split-Spoon
Sewing Machine
Abacus
Horse & Buggy
Note: Not to scale Home 1950 Office Appliances Equipment
Telephone Television Casagrande Cup
Split-Spoon Refridgerator
Washer Slide Rule
Gas Automobile
Note: Not to scale Home Office Appliances 2014 Equipment
Liquid Limit Split-Spoon smartphone 3-d LED Television
Refridgerator
Washer Tablet
Electric Automobile
Note: Not to scale Calibration of SPT Energy - Auto Hammers
Manufacturer Type ID No. Mean Energy Ratio (%) Reference Diedrich D-120 ID 26 46 UDOT Diedrich D-50 321870551 56 GRL CME 850 ID 21 62.7 UDOT BK-81 w/ AW-J rods B2 68.6 ASCE Mobile B-80 ID 18 70.4 UDOT SK w/ CME hammer B6 72.9 ASCE Diedrich D50 UF5 76 UF CME 55 UF2 78.4 Factor FDOT CME 850 296002 79 GRL CME 45 UF1 80.7 of 2.1 UF CME 85 UF4 81.2 UF CME 75 w/ AW-J rods A3 81.4 ASCE CME 75 UF3 83.1 UF CME 750 ID 4 86.6 UDOT Mobile B-57 DR-35 93 GRL CME 75 rig ID 10 94.6 UDOT cu = undrained strength Is One Number Enough??? g = unit weight T DR = relative density I = rigidity index R gT = unit weight f' = friction angle LI = liquefaction index OCR = overconsolidation f' = friction angle K0 = lateral stress state c' = cohesion intercept e = void ratio o eo = void ratio V = shear wave s qa = bearing capacity E' = Young's modulus p' = preconsolidation Cc = compression index Vs = shear wave q = pile end bearing b SAND E' = Young's modulus f = pile skin friction s = dilatancy angle k = permeability N qb = pile end bearing qa = bearing stress CLAY fs = pile skin friction Geomaterial Characterization 2014 Need a Variety of Different Methods to Truly and Fully Ascertain Soil Parameters Cone rig with hydraulic pushing system Cone Penetration Test (CPT)
• ASTM D-5778 Field Test Procedures • Continuous push at 20 mm/s Electronic Penetrometer • Add rods at 1-m vertical intervals ic = inclination
fs = sleeve friction resistance
enlargement fs u2 um = porewater pressure qt q = measured tip resistance Readings taken c every 1 or 5 cm qt = total cone tip resistance CPT • Current Phase Tranformer • Cell Prepartion Tube • Cross Product Team • Central Payment Tool • Cellular Paging Teleservice • Certified Proctology Technologist • Chest Percussion Therapy • Cockpit Procedures Trainer • Crisis Planning Team • Cone Penetration Test • Consumer Protection Trends • Color Picture Tube • Computer Placement Test • Critical Pitting Temperature • Current Procedural Terminolgy • Certified Phelbotomy Technician • Cost Per Treatment • Control Power Transformer • Choroid Plexus Tumor • Cost Production Team • Cardiopulmonary Physical Therapy • Channel Product Table • Corrugated Plastic Tubing • Conditional Probability Table • Cumulative Price Threshold • Command Post Terminal Cone Penetrometer Testing
. Electronic Steel Probes with 60° Apex Tip . ASTM D 5778 Procedures . Hydraulic Push at 20 mm/s . No Boring, No Samples, No Cuttings, No Spoil . Continuous readings of stress, friction, pressure Cone Penetration Vehicles
InDOT Cone Penetration Vehicles Geostratigraphy by CPTu in Portsmouth, Virginia Georgia Tech Anchored Cone Rig
6-tonne CPT truck with 20-tonne hydraulic pushing system
No special license
Twin earth anchors
Has been used at sites in GA, VA, NC, SC, IL, FL, AR, MO, TN, KY, and AL Downtown Atlanta, Georgia Quick Estimate of Unit Weight by CPTu
26 25 n = 950 24
) 23 3 22 Sand 21
20 Clay t (kN/m t
g 19 18 Diatomaceous 17 Mudstone
16 Organic Peat 15
14 Unit Weight, Weight, Unit 13 12 11 10 Note: f (kPa) 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 s
3 Gamma (kN/m ) = 12 + 1.5 ln( fs + 1) Friction Angle of Undisturbed Sands 50
f' = 17.6° + 11.0∙log (qt1)
45
' (deg) f
40 0.10 f' = 25.0°(qt1)
35 Uzielli et al (2013) Kulhawy & Mayne (1990) Triaxial Dataset 30 McDonald Farm
Stockholm Sand Effective Friction Effective Friction Angle, Blessington 25 0 100 200 300 400
0.5 Normalized Cone Resistance, qt1 = (qt/atm)/(vo'/atm) Friction Angle f' from CPTU for clays & silts (OCR < 2) Norwegian Institute of Technology: Senneset et al (1989); Sandven (CPT'95) 0.121 f' = 29.5 Bq [ 0.256 + 0.336 Bq + log Q ] where Bq = (u2 - u0)/(qt-vo) Senneset, Sandven, & Janbu (1989, Transportation Research Record 1235)
Notes for NTNU Method: Robertson & Campanella (1983) for Sands Bq = 0 100 Bq 1. Define Cone Resistance
= Q = Number: Nm = (qt-vo)/(vo'+a') Q = (qt-vo)/vo' 0.1
m 0.2 2. Attraction: a' = c'cotf' where f' 0.4 = effective friction angle and 0.6 c' = effective cohesion intercept. 0.8 10 1.0 3. For case where a' = c' = 0: NM = Q = (qt-vo)/vo'
4. Define Porewater Pressure
Parameter: Bq = Du2/(qt-vo)
Resistance Number, N Number, Resistance 5. Approximate Expression (degrees) f' Given for Ranges: 0.1 0.121 6. Plastification angle, bp = 0 Approx: f' ≈ 29.5º Bq [0.256 + 0.336·Bq + logQ ] CK0UC Triaxial Tests, Newbury, Massachusetts (Landon, 2007, U-Mass-Amherst) 1.0 ) ) Boston Blue Clay kPa 0.8 LL = 45; PI = 20 )/2 )/2 ( wn = 47% 3 - 1 0.6 0.4 f' = 36.7 c' = 0 y = 0.5979x sinf' R² = 0.9142 0.2 n = 16 Shear ( = q Stress, Shear 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Effective Stress, p' = (1' + 3')/2 (kPa) Newbury, Massachusetts (Landon, 2007, U-Mass-Amherst) Cone Resistance, qt (kPa) Pore Pressure, u2 (kPa) Friction Angle, f' (deg) 0 500 1000 1500 2000 0 100 200 300 400 500 600 20 25 30 35 40 45 50 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 9 9 9 Depth (meters) (meters) Depth 10 10 10 11 11 11 12 12 12 BlessingtonYield stress in soils from CPT m' = 1.1 1.0 0.9 10000 General Trend: Fissured Clays 0.85 ' = 0.33(q - )m' y t vo 0.80 Fissured Clays: m' = 1.1 0.72 (kPa) Intact clays: m' = 1.0 1000 ' ' Sensitive clays: m' = 0.9 y Silt Mixtures: m' = 0.85 Silty Sands: m' = 0.80 Clean Sands: m' = 0.72 100 Yield Stress, Yield Units: kPa 10 10 100 1000 10000 100000 Net Cone Resistance, qt - vo (kPa) Blessington Sand Site University of College Dublin (UCD) Doherty et al. (2012) Tolooiyan & Gavin (2011) Blessington Sands, Ireland (Doherty et al 2012) Cone Resistance, qt (MPa) Friction Angle, f' (deg) 0 10 20 30 40 25 30 35 40 45 50 55 0 0 1 Dense OC 1 Quartz Sands 2 D50 ≈ 0.12mm 2 3 3 4 4 5 5 6 6 Depth, z z Depth,(m) CPT-Bk 7 7 CPT-Be 8 8 CPT-Gn 9 9 CPT-Rd Triaxials 10 10 11 11 Blessington Sands, Ireland (Doherty et al 2012) Overconsolidation Ratio, OCR 0 5 10 15 20 0 1 2 3 Consolidation 4 Tests 5 6 7 0.75 Depth, z z (m) Depth, CPTs: p' = 0.33 qnet 8 and OCR = p'/vo' 9 10 11 Field Geophysics - Mechanical Wave Methods Seismograph Spectral DHT Oscilloscope + Source Analyzer SFLS SFRS + Source + Source Cased V RW Receivers Geophones s Boreholes Vp high VsHH frequencies UHT medium VsVH frequency content SRFS = Surface Refraction Survey Vertical V HV CHT low SFLS = Surface Reflection Survey Source s frequency SASW = Spectral Analysis of Surface Waves MASW = Modal Analysis (Rayleigh Waves) content CSW = Continuous Surface Waves RCHT PSW = Passive Surface Wave Testing VsHH ReMi = Reflection MicroSeis Rotary SLP = Suspension Logger Problng Source CHT = Crosshole Test Rayleigh Wave Methods RCHT = Rotary Crosshole . SASW DHT = Downhole Test BTSD SLP UHT = Uphole Test Torsional . MASW SCPTu = Seismic Piezocone Test Source VsHH . CSW SDMT = Seismic Flat Dilatometer Test . PSW VsVV BTSD = Borehole Torsional Shear Device . ReMi Shear Wave Velocity, Vs • Fundamental measurement in all solids (steel, concrete, wood, soils, rocks) • Initial stiffness represented by the small- strain shear modulus (Gdyn = Gmax = G0): 2 G0 = rt Vs where total mass density rt = gt/ga • Applies to all static & dynamic problems at -6 small strains (gs < 10 ) • Applicable to both undrained & drained loading cases in geotechnical engineering Geotechnical Methods for Site Investigation Soils Laboratory In-Situ Testing Geophysics Lab Rat Field Mouse Fruit Bat Field mouse with ball penetrometer Hybrid Geotechnical - Geophysical Test Seismic Piezocone Test (SCPTu) Hybrid Geotechnical - Geophysical Test SCPTu Sounding – Memphis, TN qt (MPa) fs (kPa) u2 (kPa) Vs (m/sec) d = 35.7 mm 0 10 20 30 40 0 100 200 300 0 1000 2000 3000 0 100 200 300 400 0 0 0 0 5 5 5 5 Vs 10 10 10 10 15 15 15 15 fs Depth(m) 20 20 20 20 u2 25 25 25 25 30 30 30 30 qt 35 35 35 35 Costs of Methods to profile Vs to 30 m METHOD TYPICAL COST Suspension Logging (PSSL) $ 35,000# Crosshole Testing (CHT) $ 20,000 Downhole Testing (DHT) $ 9,000 Surface Waves (SASW, MASW) $ 4,500 ReMi Passive Surface Waves $ 2,500 Seismic Piezocone* $ 2,000 NOTE: # Typically only economical for profiling z > 60 m * Includes 4 separate readings with depth: qt, fs, u2, and Vs SCPTu for Foundation Analyses • Shallow Foundations . spread footings . mats or rafts • Deep Foundations: . augered piles . driven pilings . drilled shafts . bored piles Shallow Foundation Response qult = Nc∙c + (B/2)∙g∙Ng + vo'∙Nq Stress, q Calculated Bearing Capacity, qult Limit Plasticity ??? Applied stress qallow = qult/FS with FS = 3 Elastic Continuum Theory GMAX = small-strain modulus Displacement, s Displacement Influence Factors Homogeneous Case: Soil Modulus constant with depth Uniform Flexible Loading Footing resting on a semi-infinite elastic half-space q BI Displacement : sq BI Deflection : r E s Es • q = applied surface stress • B = foundation width (smaller dimension) • Es = equivalent elastic soil modulus • I = displacement influence factor from elastic theory ( Poulos & Davis 1974) Download PDF of 411 page book: Elastic Solutions for Soil and Rock Mechanics (Poulos & Davis, 1974): www.usucger.org Equivalent Modulus for Monotonic Load Response Emax = 2Gmax(1+n) 2 Gmax = rt Vs rt = gt/g Georgia Tech Modulus Reduction from TS and TX Data 1 Open = Drained NC S.L.B. Sand 0.9 OC S.L.B. Sand max Closed = Undrained Hamaoka Sand Hamaoka Sand 0.8 Toyoura Sand e = 0.67 or E/E or Toyoura Sand e = 0.83 0.7 Ham River Sand max max Ticino Sand 0.6 Kentucky Clayey Sand Kaolin 0.5 Kiyohoro Silty Clay Pisa Clay Fujinomori Clay 0.4 Pietrafitta Clay Thanet Clay 0.3 London Clay Vallericca Clay 0.2 Modulus Reduction, G/G Reduction, Modulus 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Mobilized Strength, t/tmax or q/qmax = 1/FS Modulus Reduction Scheme (Fahey & Carter 1993) 1 g 0.9 E / Emax 1 f (q/ qmax ) 0.8 Note: f = 1 max 0.7 g = 1.0 0.6 g = 0.4 0.5 g = 0.3 g = 0.2 0.4 0.3 0.2 Modulus Reduction, E/E Reduction, Modulus 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Mobilized Stress Level, q/qmax Equivalent Modulus for Foundation Response Initial stiffness from small-strain shear modulus 2 . Gmax = r Vs . Emax = 2Gmax (1+n) Modulus reduction factor (Fahey & Carter 1993): g -g . E/Emax = 1 - f (Q/Qult) = 1 – (FS) . where FS = Qult/Q . Operational E = (E/Emax) ∙ Emax . for "well-behaved" soils: f = 1 and g 0.3 i.e., "vanilla clay" and "hourglass sand" Nonlinear Foundation Displacement Analyses q B (1 2 ) scenter 0.3 EMAX [1 (q / qult ) ] where s = centerpoint displacement q = applied surface stress; qult = ultimate bearing stress; B = footing width n = Poisson’s ratio Emax = initial elastic modulus = 2Gmax (1+n) See Mayne & Poulos (ASCE J. Geot. Engrg. - Jan 2001) Class “A” Prediction – Texas A&M ASCE and FHWA Symposium (1994) Geotechnical Special Publication GSP No. 41 Measured and Predicted Behavior of Five Spread Footings on Sand Class “A” Prediction – Texas A&M ASCE and FHWA Symposium (1994) qT (MPa) fS (kPa) Gmax (MPa) 0 2 4 6 8 10 12 0 100 200 300 400 0 20 40 60 80 100 0 0 0 2 2 Deltaic 2 4 4 Sands 4 6 6 6 8 8 8 Depth (m) Depth Depth (m) Depth (m) Depth 10 10 10 12 12 12 14 14 14 16 16 16 ASCE - FHWA Symposium at Texas A&M Five Footings on Sand: B (meters) = 1.0, 1.5, 2.5, 3.0 – South, 3.0 - North Class “A” Prediction – Texas A&M ASCE and FHWA Symposium (1994) Applied Axial Load, Q (MN) 0 2 4 6 8 10 12 0 K i = f(V s ) South (mm) 50 Footing 100 B = 3.0 m Vs = 210 m/s Qult = f(qt) 3 150 gT = 15.5 kN/m f' = 390 Displacement, 200 FHWA-ASCE Load Tests at Texas A&M MEASURED FOOTING RESPONSES PREDICTED LOAD-DISPLACEMENTS Class “A” Prediction – Texas A&M ASCE and FHWA Symposium (1994) TAMU Footing Load Tests (GSP 41, 1994) Measured 12000 10000 8000 B = 3 m (South) 6000 B = 3 m (North) B = 2.5 m 4000 B = 1.5 m B = 1.0 m Measured Loads, Q (kN) Loads, Measured 2000 Perfect Prediction 0 0 2000 4000 6000 8000 10000 12000 Predicted Loads, Q (kN) Class “A” Prediction Belfast Footing Load Test (June 2001) Conducted by Trinity College, Univ. Dublin (Lehane, 2003) European Foundation Prediction Symposium Belfast Test, Ireland (Data by Lehane, 2001) Index Values (%) CPT qc (MPa) Vane Cuv (kPa) Downhole Vs (m/s) 0 20 40 60 80 100 0 1 2 3 4 5 0 10 20 30 40 50 0 50 100 150 200 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 Depth (m) 7 7 7 7 8 8 8 8 PL 9 wn 9 9 9 LL 10 10 10 10 Geotechnical News (December 2001) BiTech Publishers Prediction Rating . 1. Mayne - USA . 2. Orr - Ireland . 3. Murry - NZ . 4 - 22 (anonymous) European Foundation Prediction Symposium GT Class “A” Prediction (July, 2001) 6 Predicted Measured qult = 96 kPa 5 q ult = 92 kPa 4 3 2 1 Number of Predictions 0 0 - 50 59 - 69 70 - 89 90 - 109110 - 129130 - 149150 - 169170 - 189190 - 209210 - 229229 - 300 Predicted Failure Stress (kPa) Belfast Footing Load Test GTBelfast Class “C”Footing Prediction Load Test Applied Stress, q (kPa) 0 20 40 60 80 100 120 0 20 Analytical 40 Solution 60 80 Class C Prediction 100 West Side 120 East Side Deflection (mm) 140 Measured Mean 160 cone penetrometer Pt = mini-pile Full-Scale Deep Foundation Scaling relationships for force- displacement-capacity Vs P response of axial pile s foundation fs u2 Pb qT AXIAL PILE CAPACITY QTotal = Qs + Qb - Wp FROM CONE PENETROMETER Qside = S (fp dAs) Qbase = qb Ab Method One Method Two: Rational “Direct” CPT Method or “Indirect” Method (Scaled Pile) unit side OCR, su, Ko, gt, DR, f’ friction, fp fp = fctn (soil type, pile fp = cmck Ko vo’ tanf’ type, qt, or fs and Du) Drained: qb = Nq vo’ Undrained: qb = Nc su qb = fctn (soil type, qt-ub, and degree of movement, s/B ) qb = unit end bearing Unicone CPTu Method 100 Eslami & Fellenius 1- Very soft clays, sensitive soils 2- Soft clays (1997 CGJ) 3- Silty clays - Stiff clays 5 4- Silty sands - Sandy silts www.fellenius.net 10 5- Sands, Gravelly Sands 4 (MPa) 2 3 A. At each elevation, -u t determine effective cone 1 = q = resistance: E q 2 1 qE = qt - u2 B. Plot qE vs fs for soil 0.1 1 10 100 1000 type (see chart). Sleeve Friction, fs (kPa) C. Unit Side Resistance: Soil Type Cs Value fp = Cs∙qE . 1. Very soft sensitive soils 0.080 D. Unit Tip Resistance: . 2. Soft Clay 0.050 B<0.4m: qb = qE . 3. Stiff clay to silty clay 0.025 B>0.4m: qb = qE/(3B) . 4. Silt-Sand Mix 0.010 . 5. Sands 0.004 B = pile width (m) NCHRP Synthesis 368: Cone Penetration Test Chapter 8 on Pile Foundations • www.trb.org • webforum.com/tc16 • geosystems.ce.gatech.edu RIGID PILE RESPONSE Qtu = Qs + Qb Randolph Solution Qsu = S (fp dAs) CPT PILE Qbu = qb Ab Top Displacement, wt Qt I r 2 w Emax = 2rt Vs (1+n) t 0.3 d Emax [1 (Qt / Qtu ) ] unit side 1 friction, f I p r 1 (L / d) Vs 2 V 1 (1) ln[5(L / d)(1 v)] fs Direct Unicone u2 Method Load Transfer Qb I r qt } or 2 Qt 1 Traditional Limit Plasticity + qb = unit end bearing Beta Side Resistance University of Houston NGES Texas Situated in stiff overconsolidated Beaumont clay Augered Cast-In-Place (ACIP) Piles at University of Houston O'Neill, Ata, Vipulanandan, & Yin (2002) ACIP Concrete Piles at UH (O'Neill et al. 2002) Beaumont Clay Montgomery Formation d = 0.46 m L = 15.2 m Profile from J. Benoit (2000, GSP 93) Load Test of Augercast Pile in Beaumont Clay Seismic Piezocone Sounding, University Houston Stiff Beaumont d = 0.46m clay L = 15.2m Fissured Clay Very stiff sandy clay (Montgomery Formation) Elastic Continuum Pile Solution Auger Cast-in-place Piles at Univ. Houston ACIP Pile, University of Houston Elastic Influence Factor: Input Parameters 1 I Length L= 15.20 m n = 0.50 r 1 (L / d) Diam. d = 0.456 m Ir = 0.058 1 2 (1) ln[5(L / d)(1 v)] Emax = 363,855 kPa Qcap. = 1800 kN Pile Displacements: Q/Qult = 1/FS E/Emax Qt (kN) Qb (kN) Qs (kN) E (kPa) s (m) s (mm) Qt I p 0.00 1.00 0 0 0 363,855 0.000 0.00 s 0.02 0.69 36 3 33 251,333 0.000 0.02 d Es 0.05 0.59 90 7 83 215,733 0.000 0.05 0.10 0.50 180 14 166 181,495 0.000 0.13 0.15 0.43 270 21 249 157,908 0.000 0.22 Load Transfer: 0.20 0.38 360 28 332 139,344 0.000 0.33 0.30 0.30 540 42 498 110,304 0.001 0.63 Q I 0.40 0.24 720 56 664 87,450 0.001 1.05 b r 0.50 0.19 900 70 830 68,313 0.002 1.69 Q 1 2 0.60 0.14 1,080 84 996 51,697 0.003 2.68 t 0.70 0.10 1,260 98 1,162 36,923 0.004 4.37 0.80 0.06 1,440 112 1,328 23,560 0.008 7.83 0.90 0.03 1,620 126 1,494 11,321 0.018 18.33 0.98 0.01 1,764 137 1,627 2,199 0.103 102.79 (O'Neill, 2000) ACIP Concrete Piles at UH (O'Neill, 2000) Rigid Elastic Pile Solution Axial Load, Q (kN) 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 10 20 Qtotal = Qs + Qb 30 Predicted Qb Predicted Qs 40 TopDeflection (mm) Measured Total Measured Shaft 50 Measured Base 60 Opelika National Geotechnical Experimentation Site, Alabama Mean SCPTu at Opelika NGES, Alabama Axial Load Tests: Opelika NGES, Alabama (Brown ASCE JGGE 2002) Applied Load, Q (kN) 0 1000 2000 3000 4000 0 Shaft S02 20 Shaft S04 Shaft S07 Elastic Solution Shaft S09 40 with SCPTu Data 60 80 Displacement, s (mm) s Displacement, 100 120 Compressible Pile Solution Pt I p Displacement : wt d EsL Influence factor: Ip = x1/x3 1 8 tanh(L) L AXIAL PILE Where I = displacement x1 4(1n ) 1 Pt Pt I r p (1n ) L d DISPLACEMENTS wt Influence factor from elastic continuum theory d EsL 4 1 Diameter d E (surface) x2 so (1n ) cosh(L) Es = Equivalent Elastic Soil Layer 1 Soil Modulus 4 4r tanh(L) L x E Length 3 L (1n ) L d EsM (mid-length) The proportion of load transferred from the top to base: EsL (along side at tip/toe/base) Pb/Pt = x2/x3 The proportion of load carried in side shear is: Soil or Rock Layer 2 Eb (base geomaterial Modulus of layer 2) P /P = 1 - P /P s t b t z = Depth The displacement at the pile toe/base is given by: wb = wt/cosh(L) NOTES: = db/d = eta factor (Note: db = base diameter, so that = 1 for straight shaft piles) = EsL/Eb = xi factor (Note: = 1 for floating pile; < 1 for end-bearing pile) rE = Esm/EsL = rho term. The Gibson parameter can be evaluated from: rE = ½(1+Es0/EsL). = 2(1+n)Ep/EsL = lambda factor = ln{[0.25 + (2.5 rE(1- n) - 0.25)] (2L/d)} = zeta factor L = 2(2/)0.5 (L/d) = mu factor Cone Rig at I-85 Bridge, Coweta Georgia Load Test at I-85 Bridge, Coweta County, GA GDOT Drilled Shaft Load Test: D = 0.91 m L = 20.1 m Load Test Directed by Mike O'Neill SCPTu at I-85 Bridge - Newnan, Georgia qt (MPa) fs (kPa) u2, u0 (kPa) Vs (m/s) 0 2 4 6 8 10 0 100 200 300 -100 0 100 200 300 0 100 200 300 400 0 0 0 0 2 2 2 2 4 4 4 4 Dissipation Time, t 6 6 6 6 100 sec 8 8 8 85 sec 8 75 sec 10 10 10 70 sec 10 Depth (m) Depth 80 sec 12 12 12 12 130 sec 90 sec 14 14 14 14 135sec 86 sec 16 16 16 16 210 sec 345 sec 18 18 18 18 Axial Load Response of Coweta Shaft Axial Load, Q (kN) Qt 0 2000 4000 6000 8000 0 Qtotal = Qs + Qb 10 (mm) t Pred. Qs 20 Pred. Qb Qs 30 Meas. Total Meas. Shaft 40 Displacement, w Displacement, Meas. Base Qb 50 Pile Load Tests Dead Weight Reaction Frame www.hindu.com www2.dot.ca.gov Statnamic Load Test Osterberg Cell www.statnamiceurope.com www.fhwa.dot.gov 79 GDOT Viaduct at International Boulevard near CNN, Atlanta Drilled Shaft Load Test by multi-stage O-Cells GT Class “A” Prediction March 2003 GDOT Load Test for Constructed Dimensions Viaduct at CNN of Drilled Shaft 2.9 m d = 1.68 m Residual Soils (ML/SM) 11.8 m d = 1.59 m Stage 2 O-cell Partially-Weathered Rock (PWR) 6.2 m d = 1.44 m Stage 1 O-cell GT Seismic Piezocone Sounding (SCPTu) GDOT - International Blvd. Tip Resistance Sleeve Friction Porewater Pressure Shear Wave velocity qT (MPa) fs (kPa) u2 (kPa) Vs (m/s) 0 10 20 30 0 200 400 600 800 -100 0 100 200 0 100 200 300 400 500 600 0 0 2 4 5 6 8 10 1 0 Depth (m) Depth 12 14 1 16 5 18 20 2 0 22 Notes: Electronic data lost from 15.70 m to 16.70 m due to computer malfunction. Class A Prediction - GDOT Bridge at CNN GDOT International Blvd. at CNN Axial Load, Q (MN)(kN) 0 1 2 3 4 5 6 7 8 9 10 11 12 0 10 (mm) t 20 30 Qt Predicted O-cell top down 40 Top Deflection, w Deflection, Top O-cell Creep Limit 50 Osterberg Load Cell Test High capacity sacrificial hydraulic jack Originally installed at pile base Juxtaposes side resistance of upper pile segment vs. base resistance Continue until ultimate skin friction or end bearing are reached, else capacity of the O-cell Multiple O-cell can be used at several elevations within test shaft Staged O-cell tests have now reached up to 30+ tons on single drilled shaft (http://www.loadtest.com/loadtest-uk/ about/ocell/3%20O-cell.jpg) 84 O-Cell Elastic Solution Rigid pile shaft under upward loading upper Diameter d = 2r segment 1 1 P 2 L Length 1 1 L1 Gs1ro1w1 1 r01 Rigid pile under compression loading O-Cell P1 = P2 P 4 2 L 2 2 lower Diameter G r w (1 ) r d2 = 2r2 s2 o2 2 2 o2 segment Length L2 P = applied force w = pile displacement L = pile length l = Ep/GsL = soil-pile stiffness ratio ro = pile radius = Gs2/Gsb (Note: floating pile: = 1) Ep = pile modulus Gsb = soil modulus below pile base/toe Gs = soil side shear modulus = ln(rm/ro) = soil zone of influence n = Poisson's ratio of soil rm = L{0.25 + [2.5 (1-n) – 0.25]} Calgary Drilled Shaft O-Cell Load Test by Seismic Piezocone Tests CPT05-13 Calgary Tip Stress, qt (kPa) Sleeve Friction, fS (kPa) Porewater, u2 (kPa) Shear Wave, VS (m/s) 0 10000 20000 0 200 400 600 -500 0 500 1000 0 100 200 300 400 500 600 0 Drilled 2 Shaft O-Cell Load Test 4 u2 uo- Dimensions 6 hydro d = 1.4 m L = 14 m 8 10 12 Depth (meters) (meters) Depth 14 16 18 O-Cell 20 22 24 Evaluation of Calgary O-Cell Shaft Response by Seismic Piezocone Tests Calgary Foothills Medical Center O-cell load test data App. A, page 3 of 5 O-Cell Load Test Results LOADTEST Project No. LOT-9121 (Figure 1) Loading Down Measured Below O-Cell Measured Above O-Cell Loading Up 80 70 60 d = 1.4 m 50 (mm) 40 30 20 L = 10 m 10 0 -10 L = 4 m -20 Displacement, w Displacement, -30 -40 0 1000 2000 3000 4000 5000 6000 7000 8000 O-Cell Load, Q (kN) Cooper River Bridge, Charleston, SC Deep Foundations: 2.5 m- and 3-m diameter drilled shafts with lengths of 45 to 60 m Arthur Ravenel Bridge over Cooper River, SC (Camp, ASCE GeoSupport GSP 2004) Tip Stress, q (MPa) Sleeve, fs (kPa) Porewater, ub (MPa) Shear Wave, Vs (m/s) t 0 5 10 15 20 0 50 100 150 0 1 2 3 4 5 0 100 200 300 400 500 600 0 10 20 Mean of 5 nearby SCPTs 30 Depth (m) 40 50 SCPTu 31 60 Arthur Ravenel Bridge, Charleston, SC Meas. Stage 1 Lower O-Cell: Load Down Shaft diameter Meas. Stage 2 Upper O-Cell: Load Down d = 2.6 m Meas. Stage 3 Upper O-Cell: Load Up 1 m Depth 100 0 m L = 16.3 m 50 10 m Casing 0 20 m L = 14.2 m -50 Upper 3 30 m O-Cell 2 L = 14.0 m Displacement, w (mm) w Displacement, -100 40 m Lower 1 O-Cell L = 2.5 m 48 m -150 0 10 20 30 40 O-Cell Load, Q (MN) Arthur Ravenel Bridge over the Cooper River, Charleston, SC Seismic Piezocone Sounding Golden Ears Bridge Site, Vancouver, BC Tip qt (MPa) Sleeve fs (MPa) Porewater u2 (MPa) Shear Wave Vs (m/s) 0 5 10 15 20 25 0.0 0.1 0.2 0.3 0 1 2 3 4 0 100 200 300 400 500 0 10 d = 2.6m L = 74 m 20 30 40 VS 50 Depth (m) Depth 60 fs 70 80 u2 90 qt 100 92 Application to Osterberg Load Testing 75-m long drilled shaft, Golden Ears Bridge, Vancouver, BC O-Cell Load (MN) 0 5 10 15 20 25 30 35 40 45 100 Pile diameter d = 2.6 m 75 21 m Casing 50 L = 44 m O-cell 2 25 ahamedia.files.wordpress.com Qs (stage 3) 0 Qs (stage 2) L = 27 m -25 O-cell 1 -50 Measured - Stage 3, Upper Segment Displ. L = 4 m Qt (stage 1) Displacement (mm) Displacement Measured - Stage 2, Middle Segment Displ. -75 Measured - Stage 1, Lower Segment Displ. Elastic Solution - Stage 3, Upper Segment Displ. -100 Elastic Solution - Stage 2, Middle Segment Displ. Elastic Solution - Stage 1, Lower Segment Displ. -125 93 Number of Measurements For Each Test Method 1 2 2 3 4 4 4 5 SPT CPT DMT CPTu PMT SCPTu SDMT SCPTù Vs P0 Vs Vs G tmax fs p2 fs fs fs p0 p0 PL u2 u2 u t50 2 p1 p1 q N60 qc qt qt t Geotechnical Site Characterization More Measurements is More Better Evaluation of cvh from Porewater Dissipations 200 ) 25 mm piezocone 150 c = 0.38 mm2/s kPa h ( 2 Monotonic u , , 100 Rio Sarapui, Brazil at z = 8.2 m Response 50 Measured (Danziger, et al. 1986) Approx. CE-CSSM Pressures 0 1 10 100 1000 10000 100000 Time (seconds) 1500 Hard OC Taranto Clay ) (Pane, et al. 1995) kPa Dilatory ( 1000 2 Response u CE-CSSM Solution 500 Measured at 9.1 m Hydrostatic uo Pressures, 0 0.01 0.1 1 10 100 1000 Time (minutes) SCPTù at Atlanta Airport Runway 5 Five Independent Readings of Soil Behavior: qt, fs, u2, t50, and Vs. qT (MPa) fs (kPa) u (kPa) b t50 (seconds) Vs (m/s) 0 5 10 15 20 0 200 400 600 -100 0 100 200 300 1 10 100 1000 0 100 200 300 400 0 1 2 0 3 4 5 6 5 7 8 9 Depth (m) 10 10 11 12 13 14 15 15 16 17 18 20 Seismic Resistivity Dynamic Penetrometer Test (SRDPT) for hard ground Hydraulic Rig Dynamic Driver Module (Impact, Sonic) Square Rods Shear Wave Velocity, VS Lateral Stress, L Enlargement Resistivity, W SRDPT provides Tip Stress, q 4 continuous d readings with depth GT Roto AutoSeis • Electro-Mechanical off 12-volt • AC or DC power; variable speed • Repeatable, Portable, reach 30-m depths • Can generate shear wavelets every 1 second • Patent received in February 2010 99 Continuous Vs profiling GT to 45 meters AutoSeis 0 100 200 300 ms TIME 45 45 40 35 30 25 20 15 10 5 Depth 0 (m) courtesy Dave Woeller - ConeTec Continuous-Interval Seismic Piezocone, BC q (kPa) t fs (kPa) u2 (kPa) Vs (m/sec) 0 10 20 30 0 100 200 0 1000 2000 0 100 200 300 400 500 0 0 0 0 5 5 5 5 Freq. Domain Conventional 10 10 10 10 DHT 15 15 15 15 20 20 20 20 25 25 25 25 Depth Depth (m) 30 30 30 30 35 35 35 35 40 40 40 40 45 45 45 45 50 50 50 50 Continuous-interval SCPTu at Norfolk, VA Norfolk Formation (Holocene) Yorktown Formation (Miocene) 102 International Travel: Common Link In-Situ Common Link Italy Soil Test Rig at Treporti Test Embankment Venice In-Situ Common Link Peru CPT Rig at ConeTec Yard Lima In-Situ Common Link Ireland InSitu CPT rig for University Ireland Galway In-Situ Common Link Australia IGS Cone Rig near Coffs Harbour Australia In-Situ Common Link South Africa CPT Rig built by Eben Rust In-Situ Common Link Brazil CPT Rig for Univ. Pernambuco and Federal Univ Grand du Sol thanks