The Construction Methods Of Underground Space Structure Across The Existing Tunnel

Recent years,China's urbanization is developing rapidly,and the urban population is increasing.Urban congestion and traffic congestion are becoming more and more serious.The development and utilization of urban underground space is one of the key directions for the development of the country.It is of great theoretical significance and application value to study the construction technology of underground space.Based on the combination of theoretical analysis and numerical simulation and the MIDAS-GTS finite element analysis software,taking the Lanzhou Metro Line 1 Olympic Sports Center Station as the engineering background,this paper analyzes the construction influence rule of the underground space structure across the existing subway section.(1)Through the numerical simulation of underground space construction on existing tunnel on the cross,the analysis of the mutual influence of underground space in the construction process and the structure of existing tunnel,then the plane orthogonal and oblique parallel,the three different location of the tunnel,underground space structure deformation caused by the construction of additional nodes and force comparison.(2)According to the comparison of plane position,we further explore the variation rule of additional deformation and force caused by different vertical net spacing between underground space structure and existing tunnel,and conclude that the deformation and stress of tunnel decrease with the increase of net spacing.(3)The minimum safe distance between the new foundation pit and the existing subway section is determined by the strength of the tunnel lining,the radius of curvature of the tunnel and the deformation of the track.The minimum safe distance is about one time the tunnel diameter.(4)By comparing the influence of different sections of excavation of the new foundation pit on the additional deformation and force of the existing subway section structure,it is concluded that the block construction is superior to the integral construction,and the uplift deformation and force produced by the horizontal and horizontal sections construction are the least.(5)Further explore the influence of different construction sequence of foundation pit on the deformation and force of existing subway tunnel below,simulate direct stratification,basin excavation,island excavation three excavation methods,the direct stratification of soil generated by the disturbance is obviously greater than the latter two methods,island excavation and basin excavation of additional deformation of the tunnel is not obvious difference,but the lining structure of the island excavation is superior to basin excavation method.The likelihood of structural damage is low.