UBC Theses and Dissertations
Roles of pre- and post-liquefaction stages in dynamic system response of liquefiable sand retained by a sheet-pile wall Perez, Keith
The system response in seismic soil-structure interaction problems involving soil liquefaction is expected to be influenced by both the pre- and post-liquefaction stages of soil response. This thesis focuses on determining the roles of these two stages of response in the dynamic system response of a liquefiable deposit retained by a sheet-pile wall. SANISAND-MSf model is a recently developed stress-ratio controlled, critical state compatible, bounding surface plasticity constitutive model for sands, with two ingredients of memory surface and semifluidized state, specifically designed to adequately model the pre- and post-liquefaction cyclic response of sands. The model is validated based on extensive cyclic simple shear tests and dynamic centrifuge tests from the LEAP-2020 project. A sensitivity analysis is then conducted by varying the base input motion intensity and duration. The results reveal that the amplitude of equivalent uniform base acceleration in pre-liquefaction correlates well with the timing of liquefaction triggering, and the cumulative absolute velocity of the base acceleration during the post-liquefaction stage correlates well with the post-liquefaction displacements. The study highlights the importance of accurately simulating response in the pre-liquefaction stage for the extent and timing of occurrence of liquefaction, which regulates the remaining intensity and duration of shaking, and in turn, affects the post-liquefaction permanent deformations at the system level.
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