Three-dimensional simulation of liquefiable subsoil with a steel pile under cyclic horizontal loading

抄録

In recent years, there has been growing momentum to build structures on the sea. Examples include bridges, offshore wind turbines and SEP ships (Self-Elevating Platforms). When constructing such structures, it is necessary to assess their safety during and after construction. The soil-structure evaluation is in this regard of significant importance. In particular, there is a possibility of collapse due to liquefaction, seismic and wind loads. It is therefore important to consider the behaviour of foundations and the ground of structures built on the sea when they are subjected to cyclic horizontal seismic and wind loads. Simulation of the behaviour of a pile installed in subsoil needs three-dimensional analysis because two-dimensional plane strain assumption is inapplicable. In addition, it is difficult to reproduce the actual loading conditions in pile loading tests in terms of time and cost. In this study, a three-dimensional analysis of the behaviour of a single pile and the ground under monotonic and cyclic horizontal loading was carried out using a finite element analysis method based on Biot's two-phase mixture theory with a cyclic elasto-plastic constitutive equation for sand. After verifying the validity of the analysis method and parameters through simulations of monotonic loading experiments conducted on actual ground, numerical experiments were conducted under cyclic loading.