Design of Dewatering Scheme for Deep Foundation Pit with a Multi-Objective Optimization Approach Based on Cost Controlment

In order to ensure the smooth progress of foundation pit engineering, it is necessary to identify and control the seepage risk. At present, there are few research studies and applications on the seepage risk assessment of foundation pits, and the optimization of curtain depth and the interrelation and optimal combination of design variables are rarely considered in the optimization design of foundation pit dewatering scheme based on the objective function method. According to the geological and hydrogeological conditions of the research area, a mathematical model for optimizing foundation pit dewatering was established. The model takes the minimum total dewatering cost as the objective function and comprehensively considers decision-making variables. Additionally, it also takes into account constraints such as the drawdown depth of the water level in a single well and the pumping flow rate of a single well. The calculation results indicate that the errors between the measured water levels and the simulated water levels are within ±3.5%, suggesting that the parameter inversion results are effective. The horizontal and vertical permeability coefficients of the phreatic aquifer are 3.0 m/d and 0.45 m/d, respectively, and the horizontal and vertical permeability coefficients of confined aquifer are 10.28 m/d and 1.25 m/d, respectively. The horizontal and vertical permeability coefficients of the confined aquifer are 10.28 m/d and 1.25 m/d, respectively. Nine different excavation dewatering schemes that curtain depths of 66 m, 61 m, and 56 m were designed, and the optimal excavation dewatering scheme was determined by comparing the total dewatering cost. This scheme has the advantages of shortening the dewatering time, reducing the impact of foundation pit dewatering on the surrounding environment, and saving the total cost of dewatering. The research results provide a relevant decision-making basis for managers.