Optimization of a deep foundation pit dewatering scheme in gypsum-bearing strata

The hydrodynamic changes and ground settlement induced by engineering dewatering have received much attention, and leakage between different aquifers is often neglected. Obviously, the leakage strength is crucial for the safety of underground engineering in soluble rock distribution areas. In this paper, we examined the Tianfu New Area in Chengdu, China, which contains a paste salt formation, based on numerical simulation techniques, characteristics of hydrodynamic field, leakage strength and ground settlement changes under different combinations of pumping well filter length and waterproof curtain depth were investigated. In the process of optimizing the dewatering scheme for this area, the leakage strength was innovatively included in the evaluation index. We found that as the depth of waterproof curtain increases, the trend of ground settlement and leakage strength caused by dewatering can be divided into a rapid decline phase and a gradual decline phase. However, the critical curtain depths of the two stages of ground settlement and leakage strength are different. The optimization scheme for dewatering engineering was determined under hydrodynamic, leakage strength, and ground settlement constraints. The filter length of the corresponding optimization scheme was 12 m, and the suitable depth of the waterproof curtain was 14–16 m. Our results provide an effective solution and method for optimizing the dewatering scheme in underground engineering projects with gypsum-bearing strata.