| To avoid traffic congestion,China began to build subways on a large scale.Land subsidence is an unavoidable problem in the construction of subways in soft soil areas,especially in areas with severe land subsidence such as the Tianjin Plain.In this context,taking Tianjin Binhai New Area as an example,a three-dimensional seepage stress coupled finite element model is established by using Visual MODFLOW groundwater analysis software and Midas finite element analysis software.The influence of land subsidence induced by groundwater pumping on the structure of the subway is analyzed in order to provide a theoretical basis for the construction of subways in the area.The research results are as follows:Firstly,based on the previous research results,the settlement of the tunnel and the weak areas of the subway structure is summarized and analyzed.The weak areas of the subway structure include station tunnel junction,tunnel entrance,tunnel exit,etc.Secondly,based on the existing monitoring data,the causes of the land subsidence in Tianjin Binhai New Area are analyzed,and the main factors causing the land subsidence now and in the future are further speculated.Thirdly,a three-dimensional seepage-stress coupled finite element model is established in Tianjin Binhai New Area.The groundwater pumping and building load were analyzed,and the characteristics of land subsidence caused by two different causes are analyzed.Fourthly,the mechanism and characteristics of land subsidence caused by groundwater pumping and building load are analyzed respectively,and the influence of the land subsidence on subway structure are qualitatively and quantitatively analyzed.Fifthly,according to the simulation results,prevention measures are proposed,including:soft soil reinforcement,tunnel section expansion,local structural reinforcement,etc.And a further simulation is done,the results show that prevention measures can effectively reduce the differential settlement. |
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