基坑开挖对邻近地铁盾构隧道变形以及内力的影响研究

Research on the Influence of Foundation Pit Excavation on the Deformation and Internal Force of Adjacent Subway Shield Tunnel

为研究新建基坑对邻近地铁盾构隧道变形以及内力的影响,基于某商务楼基坑,采用FLAC 3D对基坑开挖过程中邻近两条地铁盾构隧道的位移、轴力以及弯矩的变化规律展开了数值模拟分析,得到了以下结果:(1)随着基坑开挖深度的增加,邻近两条地铁盾构隧道的水平位移将不断增大,当基坑开挖完成后,隧道结构水平位移在靠近基坑一侧的拱腰处最大,在拱顶处次之,在远离基坑一侧的拱腰处则最小;(2)基坑的开挖使得靠近以及远离基坑的两条隧道轴力值分别减小了60kN^100kN和30kN^60kN,而弯矩值却分别增大了0.4kN·m^16kN·m和10kN·m^20kN·m;(3)隔断桩的设置限制了基坑周边土体向坑内的流动,使得盾构隧道最大水平位移减小了31%,最大竖向位移减小了20%,最大弯矩减小了6%。

In order to study the influence of new foundation pit on the deformation and internal force of adjacent subway shield tunnel,based on the foundation pit of a commercial building,FLAC 3D was used to simulate the displacement,axial force and bending moment of two adjacent subway shield tunnels during the excavation process.The following results were obtained:(1)when the excavation depth of foundation pit increases,the horizontal displacement of the adjacent two subway shield tunnels increases continuously.When the foundation pit is excavated,the horizontal displacement of tunnel structure is the largest at the arch waist near foundation pit,the second at the vault,and the smallest at the arch waist away from foundation pit.(2)the excavation of the foundation pit reduces the axial force values of the two tunnels close to and away from the foundation pit by 60kN^100kN and 30kN^60kN respectively,while the bending moment values are increased by 0.4kN·m^16kN·m and 10kN·m^20kN·m respectively.(3)the setting of the partition pile limits the flow of the soil around the foundation pit to the pit,which reduces the maximum horizontal displacement of the shield tunnel by 31%,the maximum vertical displacement by 20%,and the maximum bending moment by 6%.