Study On Influence Of Subway Shield Tunneling Through Existing Buildings

With the rapid development of economy and technology in the 21st century,it is one of the effective ways to solve the problem of urban public transportation to build subway in the center of densely populated cities.Due to the late planning and design of the subway,the tunnel will inevitably pass under the existing buildings.Therefore,the degree of disturbance to existing buildings and whether it will affect their safety are the key technical problems in subway tunnel construction.Based on the actual project of Meixi Hudong station～Wangcheng Slope Station of Changsha Metro Line 2,this paper analyzes the deformation characteristics of the double-line tunnel,soil and buildings in combination with the monitoring data.Large-scale numerical analysis software ABAQUS was used to establish a three-dimensional finite element model to simulate the influence of tunnel eccentricity,overlying soil thickness,structural stiffness and other factors on soil mass and building structure when the tunnel undergoes existing buildings.The main results of this paper are as follows:(1)The causes and characteristics of the deformation of the stratum and the existing buildings in the process of shield tunneling are systematically analyzed.(2)Based on the actual project,a three-dimensional model of the two-line shield tunnel underpassing the residential building was established,and the settlement data of foundation foot points obtained by monitoring were analyzed and compared,indicating that the distribution law of the simulation and the measured data was roughly the same.(3)The tunneling process of the tunnel through the existing building is simulated by setting the tunnel excavation model with different eccentricity.The results show that when the tunnel goes through the building,the settlement of the building increases with the increase of the eccentricity,and when the tunnel is at the edge of the building,it is the most unfavorable position.(4)A three-dimensional numerical model is established to analyze the influence of tunnel excavation on existing buildings under different overburden thickness.The analysis shows that the settlement of the building decreases with the increase of the overburden soil thickness of the tunnel,and when the overburden soil thickness reaches a certain size,the influence of the tunnel construction disturbance on the overburden building will be stable and unchanged.(5)The influence of tunnel excavation on existing buildings under different structural stiffness is studied by numerical simulation.The results show that the soil deformation is regulated by the stiffness of the overlying buildings,and the settlement of the buildings decreases with the increase of the stiffness.