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Khurram Shehzad st104789 14 May 2008

Interactions between Geogrid and Sand with/without Tire Chips Including Sensitivity Analyses and Simulations. Khurram Shehzad st104789 14 May 2008. Geotechnical and Geoenvironmental Engineering. Contents. Introduction Objectives Scope of Work Methodology and Laboratory Test

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Khurram Shehzad st104789 14 May 2008

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  1. Interactions between Geogrid and Sand with/without Tire Chips Including Sensitivity Analyses and Simulations Khurram Shehzad st104789 14 May 2008 Geotechnical and Geoenvironmental Engineering

  2. Contents • Introduction • Objectives • Scope of Work • Methodology and Laboratory Test • Numerical Simulations • Sensitivity Analyses • Conclusions

  3. Introduction When earth structures are constructed on soft clay deposit following problems are occurred; • Large vertical settlements • Lateral deformations

  4. Introduction Solution of the problems; • Mechanically Stabilized Earth (MSE) Structure • Lightweight backfill materials

  5. Objectives • To determine the index properties of Ayutthaya sand and tire chips-sand mixture. • To determine the • Shear strength parameters • Interaction coefficients • Efficiency of geogrid

  6. Objectives • To simulate the pullout and direct shear tests results using FE software PLAXIS 2D • Sensitivity analyses of the important parameters affecting the pullout test

  7. Scope of Work • Laboratory Tests • Numerical Simulations

  8. Materials for this Study • Ayutthayasand • Tire chips-sand mixture • Polyfelt geogrid

  9. Basic Concepts of MSE Reinforcing material Fill material Facing material

  10. Soil/ReinforcementInteraction A= PulloutResistance B=Direct Shear Resistance Soil or rigid block

  11. Laboratory Tests • Direct Shear Tests • Pullout Tests

  12. Large Scale Direct Shear Tests

  13. Longitudinal section Cross section Large Scale Direct Shear Tests Large Direct Shear Apparatus

  14. Large Scale Direct Shear Tests Direct shear failure envelopes of the sand and tire chips-sand mixture without geogrid

  15. Large Scale Direct Shear Tests Direct shear failure envelopes of the sand and tire chips-sand mixture with geogrid

  16. Pullout Tests

  17. Cross section Pullout Tests Pullout Apparatus Longitudinal section

  18. Pullout Tests Maximum pullout resistance versus normal stress for sand and tire chips-sandmixture

  19. Interaction Coefficients Direct shear interaction coefficients between backfill materials and geogrid

  20. Interaction Coefficients Pullout interaction coefficients between backfill materials and geogrid

  21. Geogrid Efficiencies Geogrid efficiencies from pullout and direct shear tests

  22. Direct Shear Tests Simulations Comparison of measured (R=0.98) and predicted (R=0.9) direct shear resistance from sand backfill using PLAXIS software (R=0.98) (R=0.9)

  23. Direct Shear Tests Simulations Comparison of measured (R=0.95) and predicted (R=0.9) direct shear resistance from tire chips-sand backfill using PLAXIS software (R=0.9) (R=0.95)

  24. PulloutTestsSimulations Comparison of measured and predicted pullout resistance from sand backfill R=0.7

  25. PulloutTestsSimulations Comparison of measured and predicted pullout resistance from tire chips-sand backfill R=0.6

  26. PulloutTestsSimulations Comparison Comparison of predicted pullout resistance from PLAXIS and FLAC for sand backfill

  27. Sensitivity Analyses Comparison of measured and predicted pullout resistance from sand Backfill at different R values usingPLAXIS software

  28. Sensitivity Analyses Comparison of measured and predicted pullout resistance from tire chips-sand backfill at different R values using PLAXIS software

  29. Sensitivity Analyses Comparison of measured and predicted pullout resistance from sand backfill at different axial stiffness values using PLAXIS software

  30. Sensitivity Analyses Comparison of measured and predicted pullout resistance from tire chips- sand backfill at various axial stiffness values using PLAXIS software

  31. Conclusions • Weight of the MSE can be reduced by 28% using tire chips-sand mixture • Cost of MSE structure can be reduced 30% by using Tire chips mixture • Efficiency of the geogrid can be increased by improving axial stiffness and interaction coefficient of the geogrid

  32. Thank You

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