With the development of the economy and the construction, the pressure of transportation on city ground increases, a single ground transportation has not fundamentally solve the urban traffic congestion situation, the urgent need to vigorously develop underground railway to solve the traffic congestion problems. Thus increasing number of subway is in operation, subway is increasingly important in city traffic. However, the construction of subway makes the excavation works' development towards large and deep direction.Based on the pit's dewatering project of the No.10 subway in Beijing, The influence of dewatering on existing station has analyzed in this thesis.In the first part of the thesis, the theories for seepage flow and ground surface settlement are briefly summarized. The consolidation theories of Terzaghi and Biot are especially compared. That the Biot theory is superior to Terzaghi theory is pointed out.Pit's dewatering caused the settlement which is a 3-dimensional fluid-mechanics coupling problem. A three-dimensional model is established via ANSYS, then using 3-D finite-difference numeric simulation software FLAC3D and its fish language, the case of the pit's dewatering project of the No.10 subway in Beijing is simulated and analyzed. The results are finally analyzed and the following conclusions are drawn: the existing station settlement increases with the dewatering time; differential settlement exists in the station after dewatering; the existing station lateral displacement is caused by dewatering, etc.The research results are important not only for the relevant engineering program but also for the similar future projects.
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