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Session 1.2 Soil Property Characterization by In-Situ Tests

Session 1.2 Soil Property Characterization by In-Situ Tests. ISSMGE August 28, 2001. 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)

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Session 1.2 Soil Property Characterization by In-Situ Tests

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

  2. 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

  3. 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

  4. Session 1.2 - In-Situ TestsQuestion 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

  5. Cell phone 2001 Session 1.2 - In-Situ TestsQuestion 1 Telephone 1909 Georgia Tech

  6. Boeing 717 2001 Session 1.2 - In-Situ TestsQuestion 1 Wright Plane 1903 Georgia Tech

  7. BMW 2001 Session 1.2 - In-Situ TestsQuestion 1 Oldfield Auto 1903 Georgia Tech

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

  9. 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 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 CLAY Is One Number Enough??? N Georgia Tech

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

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

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

  13. Shear Wave Velocity, Vs • Fundamental Measurement in all Solids (steel, concrete, wood, soils, rocks) • Initial small-strain stiffness represented by shear modulus: G0 = r Vs2(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

  14. 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) Modulus Degradation Schemes Georgia Tech

  15. 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. 22-24, 2003) Georgia Tech

  16. Enhanced In-Situ TestsSCPTu with Dissipation at Amherst Test Site Georgia Tech

  17. Enhanced In-Situ TestsSCPTu Prediction for DSS at Amherst Site Georgia Tech

  18. SCPTu at Opelika Test Site, Alabama Georgia Tech

  19. 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

  20. 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

  21. 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

  22. Session 1.2 - 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

  23. Georgia Tech

  24. 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

  25. 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

  26. 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

  27. Georgia Tech

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