Numerical Simulation of Artificial Recharge Groundwater Effect on Overlying Soft Clay Compression Control

Abstract

Soil deformation is prone to occur in the process of the foundation pit dewatering. A large number of metro existing tunnels are located in soft soil layers. The compression of soft soil poses a threat to metro existing tunnels. Previously, plenty of research on foundation pit dewatering is focused on the hydraulic head and deformation characteristics of the aquifer. However, the law of water releasing and compression deformation of overlying soft soil has not been taken seriously. In order to study the artificial recharge groundwater effect on overlying soft clay, a three-dimensional seepage–soil deformation coupling numerical model was established. The theoretical basis of the model is Darcy’s law and the principle of effective stress. A foundation pit located in Nanjing, China was selected as an example. The numerical model was used to simulate the hydraulic head and soil deformation caused by foundation pit dewatering and artificial recharge groundwater outside. The result shows that, due to the difference of hydraulic head between the aquifer and the aquitard reducing, it also has a good control effect on the deformation of the soft soil by recharging water into the aquifer. The location of recharge wells around the metro existing tunnel can control the soil deformation effectively, which could help to reduce the impact on the metro existing tunnel.