Model test study on the subsidence of high-rise building group due to variation of groundwater level

With the rapid urbanization, more and more attention has been paid to land subsidence, especially induced by the coupling effect of high-rise building groups and variation of groundwater level in soft soil areas. A model test of the subsidence of a high-rise building group undergoing the groundwater withdrawal and the recharge from different aquifers was conducted and discussed in this paper. The particle image velocimetry technology was used to analyze the long-term deformation of each soil layer, and the results were in good agreement with those measured by LVDTs. The exploitation of groundwater from the deeper aquifer was a good way to control the settlement to some extent, but the subsidence cannot be avoided completely. During the dewatering, the settlement of the soil layer was out of phase with that of the pile foundation, so the negative friction appeared along the pile and the soil settlement was hindered. The compression of two aquitards was the main reason for land subsidence, which was attributed to the decrease in pore water pressure at first following expansion of unsaturated area and the occurrence of high matric suction afterward, as well as the high compressibility of silty clay. The land subsidence caused by the variation of groundwater level was irreversible, and the behavior of water recharge and exploitation in the multilayer soils was not elastic. However, the groundwater recharge had a significant effect on restraining the settlement rate.