Numerical evaluation of a 70-m deep hydropower station foundation pit dewatering

The foundation pit of Yamansu hydropower station has an average depth of 70 m and has been excavated with five-level slopes. Lowering of groundwater level is important in excavation. In this study, drainage and pumping were conducted in dewatering. Pumping tests were performed to reverse hydraulic parameters and calibrate numerical models. Numerical simulations were performed to evaluate the dewatering scheme. In the first stage, powerhouse tailrace canal was excavated and used as a drainage channel to lower the groundwater level. Drawdown and hydraulic gradient were evaluated to prevent potential water inrush, erosion, piping, and slope failure. In the second stage, cutoff wall and pumping wells were evaluated to reduce the groundwater level. The influences of depth, permeability, and thickness of the cutoff wall were evaluated. Dewatering scheme was revised accordingly based on the evaluation. The optimized dewatering scheme, which can be used as a reference in similar engineering projects, was performed and verified successfully.

Automated summary

In this study, drainage and pumping methods were used to address the excavation of the foundation pit of Yamansu hydropower station. Pumping tests and numerical simulations were conducted to evaluate the dewatering scheme. The optimized dewatering scheme was successfully verified and can serve as a reference for similar engineering projects.