2024 年 10 巻 42 号 p. 1577-1582
The effect of liquefaction on the piled raft foundation with grid form DMWs (Deep Mixing Walls) is studied numerically. The building simulated is a 12-story RC seismically isolated residence on soft ground in Tokyo. The 3DFEM SSI (Soil Structure Interaction) model that was calibrated using seismic observation data of the 2011 off the Pacific coast of Tohoku earthquake is used. The constitutive model that can consider post-failure softening is used for the DMWs. The input wave is an extremely rare earthquake under the Japanese Building Standard Law. The analysis results shows that the area of tensile stress failure is extended in the lower part of the DMWs, mainly at both ends in the shaking direction. Some parts of the failing area lost strength due to softening. And outside of the grid form DMWs, the layers are liquified almost completely. However, the overall grid-form DWMs dose not lose the function to prevent the occurrence of liquefaction inside the grid and liquefaction-induced deformation. And the cross-sectional forces of the piles are kept within the damage limit state.
