Foundation Pit Excavation Deformation Control Study For The Xi'an Metro Line Three Xianghuwan Station

The overall development of the urban construction is looking more and more ground space and above-ground space and underground space,fundamentally solve the contradictions between urban land using space and social economic development.The development of urban underground space involves the excavation must be a certain depth of soil,foundation pit will have certain deformation,the deformation of foundation pit mainly comprises a horizontal displacement,ground surface settlement and wall of basement uplift of the three part,this paper simulated the excavation process of the foundation pit by finite element software FLAC3D;in the process of numerical simulation.Using the properties of Drucker-Prager elastoplastic constitutive model to simulate the soil,using elastic material simulation wall and the inner support,at the same time with the friction element to simulate the contact properties between the wall and soil,and simulate the excavation process of the foundation pit,obtained the soil and retaining structure of foundation pit excavation with the displacement and stress changes the situation.Taking a xi'an metro line 3 Xianghuwan station as the research object,application FLAC3D finite difference analysis,to explore the design factors,construction factors and geological factors on the deformation Foundation,analysis of the various factors on the deformation.when the wall thickness is increased to a certain extent,the maximum surface settlement decreases by increasing the thickness of the wall is limited,not to reduce the deformation of foundation pit;when the depth of diaphragm wall is more than a certain extent,continue to increase the embedded depth of the wall of small deformation;when the prestress exceeds the design axial force of foundation pit,the maximum surface settlement is no longer obvious,and easily lead to the support pressure generated bar buckling;when the ground overload,increase of surface subsidence is very obvious,in the construction should avoid overloading.Through a comprehensive comparative analysis of the results,we obtained the main factors affecting foundation pit deformation.Based on various factors analysis results show reasonable stiffness and buried depth design parameters,not only can effectively control the deformation of the pit,and also avoid causing increase project investment,thus summarizes the excavation deformation control measures,so as to optimize the design provides a method and basis.