Research On Dewatering Method By Deep Foundation Excavation In Soil Layers With Artesian Water And On Its Induced Building Settlement Near Foundation Pit

Based on the key development program of Wuhan city, Wuhan Yangtze River Crossing Tunnel Project, the ground surface and building settlement induced by deep foundation excavating and dewatering in soil layers with artesian water in this thesis.In the first part of the thesis, the theories for calculating deep foundation dewatering and ground surface settlement are briefly summarized. Some main ambiguous concepts in hydrogeology, design method of deep foundation dewatering and analytical method of ground surface settlement are discussed in detail.In the second part, with the help of the fluid-mechanical coupling function in 3-dimentional finite difference program FLAC^3D, the 3-dimentional coupling analysis on deep foundation excavation and dewatering is carried out. The method for predicting the ground water level during dewatering and the importance of the factors which influence the dewatering effect and seepage flow field is analyzed. It shown that the deeper the observation well is, the higher the water level is in the well. The feature and factors affecting the ground surface settlements due to dewatering, the ground surface settlement induced by artesian head and stiffness of the maintenance structure are also studied. Further, the building settlement and the difference of ground settlements induced by dewatering in the case of existng buildings on the ground or not, different positions between buildings and deep foundation pit, foundation characteristics (such as area, depth, stiffness, format, etc), interactions between adjacent buildings are computed and evaluated.In the last part, with dewatering and settlement calculation method presented in this article, the dewatering and excavating process of Wuchang shield shaft is numerically simulated, and the computed values are compared with the observations. The dewatering process of Hankou shield shaft is also simulated, and the reinforcement effect of soft soil layer is evaluated.The research results are important not only for the relevant engineering program in Wuhan Yangtze River Crossing Tunnel Project but also for the similar future projects.