Numerical analysis on seismic behavior of soil around pile group by 3D effective stress finite element method

The behavior of soil around a pile group was investigated based on a series of dynamic effective stress analyses through the three-dimensional finite element method, simulating centrifuge shaking table tests on soil-pile-structure systems with closely spaced piles reported in a previous study (Suzuki et al., 2006). The computed results show that the mechanism of subgrade reaction in a pile group in dry ground is different from that in saturated ground. The horizontal compression normal stress of the soil at the front side of the pile mainly contributes to the subgrade reaction in dry sand, while pore water pressure reduction at the back side of the pile is the main cause, rather than the normal stress in saturated sand. A series of computed results were found to support the presumed mechanisms of closely spaced pile groups described in a previous experimental study.