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# Soil Property Characterization by In-Situ Tests

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Soil Property Characterization by In-Situ Tests
Session 1.2 Soil Property Characterization by In-Situ Tests ISSMGE August 28, 2001 Georgia Tech

Session 1.2 - Soil Property Characterization by In-Situ Tests
Chair: Max Ervin (Australia) Discussion Leader- Paul W. Mayne (USA) Panel Members: Martin Fahey (Western Australia) Ranier Massarsch (Sweden) An-Bin Huang (Taiwan) Georgia Tech

Session 1.2 - Soil Property Characterization by In-Situ Tests
Use of Enhanced In-Situ Tests, notably hybrid devices. Importance of small-strain measurements in geotechnical deformation analyses Reliability and Variability Issues Repeability of soundings Class ratings for equipment. Georgia Tech

Session 1.2 - In-Situ Tests Question from Topic 1
Is it time to retire the Standard Penetration Test (SPT) ? To consider this prospect Let us go back - back in time Georgia Tech

Session 1.2 - In-Situ Tests Question 1
Telephone 1909 Cell phone 2001 Georgia Tech

Session 1.2 - In-Situ Tests Question 1
Wright Plane 1903 Boeing 717 2001 Georgia Tech

Session 1.2 - In-Situ Tests Question 1
Oldfield Auto 1903 BMW 2001 Georgia Tech

Session 1.2 - In-Situ Tests Question 1
Geotech Test 1902 Geotech Test 2002 ? Colonial Charles Gow of Raymond Pile Company Georgia Tech

N Is One Number Enough??? p' = preconsolidation SAND CLAY
cu = undrained strength gT = unit weight IR = rigidity index ' = friction angle OCR = overconsolidation K0 = lateral stress state eo = void ratio Vs = shear wave E' = Young's modulus Cc = compression index qb = pile end bearing fs = pile skin friction k = permeability qa = bearing stress CLAY DR = relative density gT = unit weight LI = liquefaction index ' = friction angle c' = cohesion intercept eo = void ratio qa = bearing capacity p' = preconsolidation Vs = shear wave E' = Young's modulus  = dilatancy angle qb = pile end bearing fs = pile skin friction SAND N Georgia Tech

Numerical Simulations
Use of In-Situ Tests Numerical Simulations Finite Elements Strain Path Finite Differences Discrete Elements PLAXIS, FLAK, SEEP3d, ABAQUS, CRISP, ADINA, GEOSLOPE Georgia Tech

Enhanced In-Situ Tests
Cone Pressuremeter Seismic Piezocone Dilatocone Seismic Dilatometer Resisitivity Cone Georgia Tech

SCPTu Sounding, Memphis, Tennessee
Real-Time readings in computer screen Penetration at 2 cm/s Sand Clay Crust Georgia Tech

Shear Wave Velocity, Vs Fundamental Measurement in all Solids (steel, concrete, wood, soils, rocks) Initial small-strain stiffness represented by shear modulus: G0 = r Vs (alias Gdyn = Gmax = G0) Applies to all static & dynamic problems at small strains (gs < 10-6) Applied to undrained & drained cases Need Reduction Factor for Relevant Strain Levels. Georgia Tech

Modulus Degradation Schemes
Kondner (1963) Ramberg-Osgood Duncan & Chang (1970) Seed & Idriss (1971) Hardin & Drnevich (1972) Jardine, et al. (1986) Prevost & Keane (1990) Vucetic & Dobry (1991) Tatsuoka & Shibuya (1992) Fahey & Carter (1993) Whittle & Kavvadas (1994) Puzrin & Burland (1996, 1998) Tatsuoka, et al. (2001) Georgia Tech

PreFailure Deformation Characteristics of Geomaterials
SPECIALTY CONFERENCES Sapporo (1995): Edited by Shibuya, Mitachi, & Miura. London (1997): Edited by Jardine, Davies, Hight, Smith, & Stallebrass. Torino (1999): Edited by Jamiolkowski, Lancellotta, & LoPresti. Lyon (Sept , 2003) Georgia Tech

Enhanced In-Situ Tests SCPTu with Dissipation at Amherst Test Site
Georgia Tech

Enhanced In-Situ Tests SCPTu Prediction for DSS at Amherst Site
Georgia Tech

SCPTu at Opelika Test Site, Alabama
Georgia Tech

Axial Load Test at Opelika, Alabama
Q (total) Drilled Shaft 01 (cased) d = 0.91 m L = 11.0 m Q shaft Q base Georgia Tech

Topic 3: Reliability, Repeatability, Calibration, & Interpretation Issues
Prior Comparative Studies: Lunne, et al. (In-Situ'86) Tanaka (CPT'95) Electric vs. Electronic Penetrometers Subtraction vs. Tension Cones for fs Smooth vs. Rough Steel - Interface affecting fs measurements. Lunne, Robertson, & Powell (1997): Recommend different Class I to Class IV penetrometers for CPT work. Georgia Tech

Effective Strength Parameters
Bearing Capacity Theories Durgunoglu & Mitchell (1975); Vesic (1977); Robertson & Campanella (1983); Salgado et al. (1994); Jamiolkowski & LoPresti (2000) CSSM Dilatancy Approach using DR from CPT (Bolton, 1986) Effective Stress Method (Senneset, Janbu & Sandven, 1989) y-f’ (psi-phi) “Sci-Fi” Georgia Tech

Session Summary Geotechnical Investigations need to Employ Modern Technologies: Seismic Piezocone, Flat Dilatometer, Cone Pressuremeter, Geophysical Methods Small-Strain Stiffness (G0) is Relevant to Monotonic (Static) and Dynamic Geotechnical Problems Address issues of Calibration,Equipment, Reliability, and Interpretation. Georgia Tech

Georgia Tech

Enhanced In-Situ Testing
Recommendations for Geotechnical Research Need more consistent methods for interpretation of in-situ tests: Vane - Limit Equilbrium Pressuremeter - Cavity Expansion Piezocone - Strain Path Pile Foundations - Limit Plasticity Georgia Tech

Enhanced In-Situ Testing
Recommendations for Geotechnical Research Need additional numerical & analytical simulations of multiple tests using Finite Elements Strain Path Method Discrete Elements Finite Differences Georgia Tech

Enhanced In-Situ Testing
Recommendations for Geotechnical Research Develop additional sensors + channels New digital cone systems Seismic Piezocone Pressuremeter Dielectric-Resistitivity Seismic Piezocone Gamma-EM-Dilatocone Better use of statistical methods Georgia Tech

Georgia Tech

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