In this paper, the uplift mechanism of buried pipe subjected to cyclic simple shear in dry sand was discussed. The uplift displacement of buried pipe and the contact force distributions between soil particles are calculated by Distinct Element Method. As a result, it was found that buried pipe model having a large diameter with the same density as soil particles was easier to float up than the soil particle which constitutes the surrounding ground. And as the uplift mechanism, it was clarified that the buried pipe model uplift was due to reaction force from the lower ground, when the pipe model move laterally.
The behavior of buried pipe is influenced by the interaction between structure and ground. The buried pipe is subjected to large buoyancy during liquefaction of surrounding soil. The buried pipe floats up when the buoyancy forces becomes larger than the effective overburden loads.
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 force acting on the structures. Yuasa et al. (2000) clarified that the uplift of the underground structures was caused by the transmission of pressure from liquefiable soil and preventing the transmission reduced the uplift displacement. In contrast, Suehiro et al. (2003) revealed that the failure surface in soil extended to the ground surface and the buried pipe floated up along this failure surface when the buried pipe moving horizontally by the seismic force. However, the resultant force acting on the pipe by shear deformation and the behavior of soil particles of surrounding pipe are not clear.
The purpose of this study is to clarify the uplift mechanism of the buried pipe subjected to cyclic simple shear in dry sand by Distinct Element Method.
