Soil-water coupling analysis on seismic behavior of an alternately layered sand-silt ground with different foundation system

Abstract

In evaluating the damage caused by earthquakes, attention has been paid exclusively to ground liquefaction of sandy grounds during earthquakes. However, studies of post-seismic damage, especially damage to clayey/silty grounds have also been reported. In this paper, the behavior of an actual alternately layered sand-silt ground and foundation-superstructure system during and after an earthquake is investigated. The calculations are carried out using a 2D/3D soil-water coupling analysis program named as DBLEAVES that can not only describe the static and dynamic behavior of natural complex grounds, but also can solve soil-structure interaction problems. Two cases with different foundations (long-pile type foundation and dense short-pile type foundation) are analyzed. A rotating hardening elastoplastic model named as Cyclic Mobility model (CM Model) is adopted in the analyses to properly describe the nonlinear behavior of soils during and after large earthquake motions. The results show that the long-pile type foundation is more suitable to resist uneven settlement while the short-pile type foundation has a better resistance to ground liquefaction. No matter what kind of case may be, not only the liquefaction but also the long-term settlement after the earthquake should be taken into consideration seriously.