Three-dimensional Force-deformation Characteristics Research Of Subway Station With Cover And Excavation Top Down Method Construction Process

:With continuous development ofChina’s economy, the scale of city is also continuing expansion, traffic congestion has gradually become a bottleneck restricting urban development. Developing subway transportation has become an important measure to alleviate road traffic congestion. In the bustling city, subway station construction must be considered to minimize the impact of construction on urban transport and the neighboring buildings.This article discusses thetechnical characteristics ofsubway stationconstructionby open excavation method、cover-excavation method and cover and excavation top down method. Relies on a Station of Beijing Subway,combine with field test results and numerical simulation results, research the force and deformation variation rules of top plate、medium plate、bottom plate and side walls with the construction process; the force change feature of the middle pile(column) with the construction process; the mechanical convert characteristics of plates-wall connection point, pile-plate connection point, downward guide wall of top plate over the construction process. Evaluate the security of stationand the impact on the surrounding buildings by analyzing the settlement of soil outside foundation pit and the differential settlement between enclosure structure and middle pile(column) during construction.Research and optimize the key technologies of enclosure structure, foundationexcavation, structure construction in cover and excavation top down method, to provide a reference for similar projects in future.Research shows:(1) Force state of the middle pile(column), top plate、medium plate、bottom plate and side walls constantly changes during the construction, the corresponding stress value gradually increases with the construction.(2) Themechanical status of plates-wall connection point, pile-plate connection point, downward guide wall of top plate changes more obvious, stress almost within the allowable range in construction process.(3) During the construction process, the differential settlementvaluebetween middle column and sidewall and the horizontal displacement value of the cantilever pile and envelope pile are small, meet the requirements of appropriate standards; settlement of buildings nearby the station is also within the scope of standard requirements.Construction process is safety and reliability, do a less impact on the surrounding environment.