Dewatering Design and Subsidence-monitoring of Deep Foundation Pit Adjacent to Existing Railway Line

Research purposes: Dewatering from deep foundation pit will certainly arouse the subsidence of surrounding environment.According to the condition that the deep foundation pit of the building of Tianjin West Station of Beijing-Shanghai High-speed Railway was adjacent to the existing railway line,a three-dimensional seepage model was used to simulate the seepage field inside and outside the deep foundation pit and the effective dewatering design scheme was adopted to ensure the safety of excavation of deep foundation pit and the traffic of existing railway.At the same time,the monitored data on subsidence were analyzed for providing the reference to the similar works.Research conclusions:In order to ensure rationality and validity of a dewatering design,the dewatering design must consider engineering geological conditions,hydraulic geological conditions and foundation bracing system to select reasonable hydrological parameters and make analysis of seepage flow with three-dimensional seepage model.The dewatering should be conducted strictly according to the dewatering design scheme with immediate dewatering and dynamic control to reduce dewatering depth of pressure-bearing water for effective controlling the subgrade subsidence around the foundation pit as much as possible and ensuring the railway traffic.