Study On The Influence Of Shallow-subsurface Excavation Station Construction On The Overlying Complex Interchange

The overall length of Tianxingqiao Station is 214 meters,which in the fist-stage project of rail transit circle in Chongqing.According to the peripheral environment and geological environment,the tunnel is constructed by open cut method and undercutting method respectively.The undercutting section is a layer-2-undergroung-floors island station which is located in the road below,whose length is 195.74 meters.A lot of buildings are around the station and the engineering environment is quite complicated here.Depending on the Tianxingqiao Station Project, in combination with the theoretical analysis and the monitoring measurement,this paper employs the Finite Element Method to make an intensive study about the construction mechanical effect of the three representative location(the overlap of the station main structure,the Fengtianlu interchange under-crossing and the ramp B,the station main structure crosses the intersection of ramp A and ramp B,the station main structure crosses the pedestrian bridge),which can make a guide in design and construction effectively.Moreover,it can be a reference in the construction of similar subway station to some degree.And the main research findings are as follows:(1)Adopting the theoretical analysis,the field monitoring and the numerical simulation,this paper researches the influence station construction on the overlying complex interchange.The computing method of longitudinal strain under the influence of the construction is deduced,which proposes theoretical basis for the following numerical simulation.(2)A three-dimensional finite element model is established with the application of the finite element analysis software Midas GTS.The construction mechanical effect is analyzed on the overlap of the main station,the under-crossing and the ramp B.Then a detailed analysis about the displacement and main stress variation characteristics of the wall rock are researched.The deformation and internal force of the under-crossing and the ramp B are studied in the construction of parallel crossing.Finally by comparing the numerical simulation results with the field measured data,the numerical simulation results are proved correct.(3)A three-dimensional finite element model is established with the application of the finite element analysis software Midas GTS.The construction mechanical effect is analyzed on that the main station crosses the intersection of ramp A and ramp B.Then a detailed analysis about the variation characteristics of displacement and shear stress of the wall rock are researched.And the supporting structure stress characteristics and the plastic zone characteristics of the wall rock are discussed.The vetical deformation of ramp A is studied in the construction of vertical crossing.The theoretical calculation is analyzed about the settlement of ramp A.Finally by comparing the theoretical calculation results with the field measured data and numerical simulation results,the numerical simulation and the numerical simulation results are proved correct.(4)A three-dimensional finite element model is established with the application of the finite element analysis software Midas GTS.The construction mechanical effect is analyzed on the crossing pedestrian bridge section. The internal force and displacement variation characteristics of the pile foundation are studied.