The purpose of this study is to clarify the uplift mechanism of various sized buried circular structures subjected to cyclic simple shear in the earthquake. In this study, the 2-dimensional discrete element method (DEM) was used. This demonstrated that the upper resultant force acting on it and the uplift displacement of it become larger as the diameter of the structure becomes larger. In addition, it was found that the uplift behavior of the structure is influenced by the displacement of the surrounding ground.
Large earthquakes occur frequently in Japan. A lot of agricultural land and facilities have been seriously damaged by such earthquakes. Especially, the underground structures has accounted for a large percentage of the total amount of damage. In general, ground liquefaction occurrs and the underground structure such as buried pipeline is subjected to large buoyancy during earthquake. The underground structure floats up when the buoyancy exceeds the effective overburden loads acting on the structure. However, it is easily predicted that the effect of interaction between the ground and structure should be considered. Koseki et al. (1997) performed shaking table tests to evaluate the safety factor against uplift for the underground structures based on the equilibrium of vertical forces acting on the structures. Suehiro et al. (2003) conducted large-scale shaking table test and numerical simulation using discrete element method in order to study the mechanism of uplift behavior of buried pipe. As a result, it was clarified that the underground structures subjected to seismic force tend to float up not caused by the pore water pressure but the resistance force from the surrounding ground under the structure. On the other hand, Kawabata et al. (2005) clarified the uplift mechanism of the buried pipe when the surrounding ground is subjected to cyclic simple shear deformation.