Dynamic Pile-Soil Interaction in Laterally Spreading Slopes
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The collapse of buildings and infrastructure is an unfortunate consequence of major earthquakes (e.g., the 1964 Alaskan earthquake, the 1995 Kobe earthquake in Japan and the 2007 Pisco earthquake in Peru). Liquefaction-induced lateral spreading is known to be one cause of severe damage to deep foundation systems. However, the dynamic soil-structure interaction between liquefied soil and piles is extremely complex and further work is required to define the appropriate design pressures and to understand the mechanisms at work. This thesis presents the findings of an experimental program carried out using the large geotechnical centrifuge at C-CORE in St John’s Newfoundland, to investigate the mechanism of lateral spreading and its implications for dynamic soil-pile interaction. Soil and pile responses were measured using accelerometers, pore pressure transducers, and digital imaging using a high speed camera. Using these images, transient profiles of slope deformation were quantitatively measured using Particle Image Velocimetry (PIV). These tests illustrate the potential for earthquake shaking to excite the natural frequency of the liquefied soil column, which can lead to increased transient lateral pressures on piles in liquefiable ground. This study recommends that this potential for “auto tuning” should be anticipated in design and proposes a new limiting pseudo-static backbone p-y curve for use in the design of piles subjected to lateral spreading ground deformation.