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By Claudia Medina Marcelo Gonzalez Ahmed Elgamal Rensselaer Polytechnic Institute

NEES-Pile: Experimental and Computational Study of Pile Foundations Subjected to Liquefaction-Induced Lateral Spreading FEM Simulation of test SG1. By Claudia Medina Marcelo Gonzalez Ahmed Elgamal Rensselaer Polytechnic Institute August 20 th , 2007.

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By Claudia Medina Marcelo Gonzalez Ahmed Elgamal Rensselaer Polytechnic Institute

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  1. NEES-Pile: Experimental and Computational Study of Pile Foundations Subjected to Liquefaction-Induced Lateral SpreadingFEM Simulation of test SG1 By Claudia Medina Marcelo Gonzalez Ahmed Elgamal Rensselaer Polytechnic Institute August 20th, 2007

  2. SIMULATION: Model(Ahmed Elgamal, Zhaohui Yang, Jinchi Lu) • VARIABLES OF THE SOFTWARE: • MASS DENSITY • REF. SHEAR WAVE VELOCITY • REF. MEAN CONFINEMENT • CONFINEMENT DEPENDENCE COEF. • Ko • COHESION • FRICTION ANGLE • PEAK SHEAR STRAIN • NUMBER OF YIELD SURFACE • DILATION ANGLE • CONTRACTION PARAMETER 1 • CONTRACTION PARAMETER 2 • DILATION PARAMETER 1 • DILATION PARAMETER 2 • LIQUEFACTION PARAMETER 1 • PERMEABILITY COEFICIENT CYCLIC 1D

  3. Dilation angle degree Liquefaction parameter SIMULATION: Model(Ahmed Elgamal, Zhaohui Yang, Jinchi Lu) C1: DICTATES THE RATE OF PORE PRESSURE BUILDUP UNDER UNDRAIN CONDITION, 0.3 – 0.0 (VERY LOOSE TO VERY DENSE SAND) C2: REFLECTS THE EFFECT OF OVERBURDEN PRESSURE ON CONTRACTION BEHAVIOR, 0.2 – 0.6 (VERY LOOSE TO VERY DENSE) D1: DICTATES THE RATE OF VOLUME EXPANTION (OR REDUCTION OF PORE PRESSURE), 0.0 – 0.6 (VERY LOOSE TO VERY DENSE) D2: REFLECT THE EFFECT OF ACCUMULATED SHEAR STRAIN ON DILATION BEHAVIOR, 10 LIQUEFACTION PARAMETER: DICTATES THE EXTENT OF SHEAR STRAIN ACCUMULATION, 0.025 – 0.0 (VERY LOOSE TO VERY DENSE)

  4. Numerical simulation QUICK DISSIPATION 2 SEC 4 SEC We need to improve in the dilation coef. Quick increment CALIBRATION using Taboada’s centrifuge tests (Gonzalez, 2006)

  5. Numerical simulation 0.475 m 2.50 m 5.00 m 7.50 m CALIBRATION using Taboada’s centrifuge tests (Gonzalez, 2006)

  6. CALIBRATION using Taboada’s centrifuge tests (Gonzalez, 2006)

  7. CALIBRATION using Taboada’s centrifuge tests (Gonzalez, 2006)

  8. Ottawa Sand Dr=40–50% k=1E-5m/sec r= 1975kg/m3 S= 100% 0.3 6m Acc (g’s) - 0.3 0 5 10 15 Time (sec) PREDICTION SG-1 test (Gonzalez, 2006) Model and Input Motion

  9. PREDICTION SG-1 test (Gonzalez, 2006) Excess of Pore Pressure

  10. PREDICTION SG-1 test (Gonzalez, 2006) Lateral Permanent Displacement

  11. PREDICTION SG-1 test (Gonzalez, 2006) Response Profile

  12. SIMULATION LG-0 (Forcellini, 2007) Actual Input LG-0

  13. SIMULATION LG-0 (Forcellini, 2007) Accelerations

  14. SIMULATION LG-0 (Forcellini, 2007) Excess of Pore Pressure

  15. SIMULATION SG-1: Model and Actual Input SG-1

  16. SIMULATION SG1 with Actual Input Results at 8.5 sec (22.5 sec)

  17. SIMULATION SG1 with Actual Input (Medina, 2007) Results at 8.5 sec (22.5 sec)

  18. SIMULATION SG1 with Actual Input (Medina, 2007) Deflection Time Histories

  19. SIMULATION SG1 with Actual Input (Medina, 2007) Excess Pore Water Pressure Time Histories

  20. Concluding Remarks • Three simulations were performed using actual input motion from SG-1 test (0-8.5 sec) • Simulation 1: Parameters calibrated using Taboada’s centrifuge test (Gonzalez, 2006) gives a maximum permanent displacement equal to 8 mm. • Simulation 2: Parameters calibrated using LG-0 test (Forcellini, 2007) gives a maximum permanent displacement equal to 2.3 m. • Simulation 3: New parameters, completely different to first two simulations, gives a maximum permanent displacement equal to 32 cm. • We have a problem!

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