Solutions to Problems Encountered in Deep Foundation Pit Affected by Multi-layer Groundwater

The groundwater level in Beijing has generally risen under the influence of ecological water replenishment in recent years, which poses a great threat to the safety of foundation pit. A series of problems encountered in the construction of a foundation pit supporting project affected by multi-layer groundwater in Dongxiaokou area, Changping, Beijing, as follows: water stop curtain leaking; surface collapse; sand flowing between pile. Through the analysis of the reasons and combined with field tests, the effective technical treatment measures were adopted such as decompression of drainage holes, "double liquid" sealing of L-shaped grouting pipes, "formwork support" between piles, etc. The disease problems in the process of foundation pit excavation were solved, which ensured the safety of the foundation pit.