About the author:

1. Shanghai Urban Construction Municipal Engineering （Group） Co., Ltd., Shanghai 200032, China;2. College of Civil Engineering, Tongji University, Shanghai 200092, China

Abstract:

Soft soil strata are susceptible to construction disturbances, and improper design of foundationexcavation dewatering can severely affect the surrounding environment. Taking the deep foundationexcavation project of a station under construction in Shanghai as an example, through on⁃site pumpingand recharge tests, the impact of dewatering on the settlement of the surrounding strata was studied, andcorresponding measures were proposed based on the results of the recharge tests. The test results showedthat although the recharge of confined aquifer levels in each layer was relatively slow, pumping should notbe stopped for a long time during the decompression dewatering stage. The ground settlement caused bypumping and lowering confined aquifer exhibited a radial funnel shape centered around the pumping well,with deep⁃layer settlement mainly concentrated in the ⑧2confined aquifer, accounting for about 44.8%of the total settlement. After stopping pumping, the strata settlement showed a certain lag in rebound withthe recovery of water levels. To protect sensitive buildings around the foundation excavation, it isrecommended to adopt comprehensive measures such as extending the bypass path and arrangingemergency recharge wells to control the impact of decompression dewatering inside the pit on the waterlevels outside the pit.