2024 年 10 巻 39 号 p. 1480-1485
In previous research works, soil-pile dynamic interaction has mostly been investigated considering an isolated pile supported structure with soil’s cyclic response being considered as truly undrained. However, previous earthquakes such as the 1995 Kobe earthquake highlighted that spatially located piles installed in a sloping ground may behave differently during the application of earthquake loading particularly owing to the differences in the mechanism responsible for the mobilization of kinematic effects (i.e., soil-fluid-pile interaction). This stems from the fact that during the course of shaking (particularly for long-duration earthquakes), pore-pressure redistribution phenomenon is very likely not only in upwards direction but also along the spatial zone of lateral spreading and therefore may govern the magnitude of co-seismic kinematic moment mobilized by the spatially located piles. The above-mentioned mechanisms contributing to the mobilization of kinematic effects for the spatially located piles have not been studied till date which is very critical as the densely populated cities with multiple adjacent pile supported buildings are expected to experience strong shakings in the near future. To this end, this paper shed novel insights on the mobilization of kinematic effects for spatially located piles based on the dynamic centrifuge testing. From the centrifuge experiments conducted on a uniformly liquefiable model and a stratified soil model inclined with 5-degrees comprising of spatially located piles, we found that lateral seepage played a significant role in the mobilization of kinematic moments towards the bottom of pile. To this end, it is important to correlate the internal stresses mobilized along the pile with the generated excess pore pressure. It is also recommended to design pile foundation as a spatially located structure along the zone of lateral spreading in order to achieve safer design loads.
