南京长江漫滩区基坑开挖与降水对既有地铁隧道影响的数值分析

基坑开挖与降水会使邻近既有地铁隧道产生内力调整和变形重分布,影响其正常使用和运营安全。开挖与降水过程中基坑支护、地基土体和隧道结构之间相互作用和影响,其变形稳定问题是一个复杂的三维力学问题,可采用三维数值模拟进行分析。基于FLAC3D有限差分数值分析软件,对南京长江漫滩区某大面积基坑开挖全过程进行模拟,重点分析开挖卸荷、降水对邻近2条地铁隧道结构的变形影响。计算表明,基坑开挖卸荷时产生的结构变形量值和变形相对曲率较小,未超过安全控制值;但降水产生的结构沉降变形量值较大,对地铁线路的正常运行产生不利影响。

Study on the Effect of Pit Excavation and Dewatering on Metro Tunnels in Floodeplain Area of Yangtze River

Abstract: Redistribution of stress and deformation fields of metro tunnel structures happens when an adjacent pit excavation and dewatering are carried out,and affects the normal operation and safety of the subways. Pit support, fondation soil and tunnel structure interact, and its deformation are an 3 dimensional complex mechanical problem that can be analysed by 3-D numerical simualtion. The exvation prcocesses of a large and depth pit in floodeplain area of Nanjing Yangtze river is simualted by FLAC3D in this paper, and the deformation of two adjacent subway tunnels caused by excavation unloading and dewatering is substantively analysed. It is indicated that the deformation value and deformation curvature of tunnels structure are small and do not exceed the safaty thresholds. However, the settelment deformations resluts from dewatering are so large and affect on the normal operation and security of subways in direct.