Investigation of the Effects of Successive Liquefaction Occurrence on Piles Located in Level Ground with an Inclined Base Layer-A Physical 1g Shake Table and Laminar Shear Box Model

Moradi, Mohammad | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53343 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Haeri, Mohsen
  7. Abstract:
  8. The phenomenon of soil liquefaction has caused significant damage to deep foundations of engineering structures such as bridges and buildings in past earthquakes. In recent years, many researchers have studied the effects of soil liquefaction on the pile response, but there are still many unknowns that require further research and study. The present study is part of a comprehensive research that involves several Ph.D. and master students at Sharif University of Technology (SUT). In this study, the effects of soil liquefaction on two pile 2×2 groups (one with a lumped mass and another without) in a level ground with a sloping bed were investigated. A surface non-liquefied layer was also present. Four loading steps were applied on the original physical model which has been prepared for study of the effect of lateral spreading and some post liquefaction and post lateral spreading on these piles. The results of three post lateral spreading shakings have been investigated in this research. The mentioned experiments were performed using SUT Laminar shear box with inner length, width, and height of 306, 172 and 180 centimeters, respectively and the shaking table of the Earthquake Engineering Research Center at SUT. The piles, the soil around the piles and the free field were heavily instrumented to measure various parameters during and after the shakings. In this study, the results were examined in the form of time histories of acceleration, displacement, bending moment, pore water pressure, lateral pressure on the piles, and the p-y curve for the piles. The results of this study showed that due to the sloping bed of the model, despite the flatness of the ground surface, lateral spreading in liquefiable layer occurred, however with a milder extent. In this study, the maximum bending moment and kinematic force applied to the upslope piles was more than those of the downslope piles, due to the shadow effect. The effect of the lumped mass of the upper structure in grounds with liquefaction potential was investigated and it was observed that the pile group with lumped mass has a higher bending moment and kinematic force than the pile group without the lumped mass. This is an emphasis on applying the mass of the upper structure on the cap of the pile groups in physical model experiments, and perhaps a more precisely simulation of supper structure may result in a more realistic outcome
  9. Keywords:
  10. Physical Modeling ; Level Ground ; Pile Group ; Liquefaction ; Slope Ground ; Shaking Table Test ; Post Liquefaction ; Post Lateral Spreading

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