斜抛撑支护基坑开挖对邻近综合管廊的影响分析

以福建省厦门市某邻近既有综合管廊基坑开挖项目为例,针对SMW工法桩+斜抛撑支护体系,采用FLAC3D有限差分软件建立综合管廊的三维数值模型,进行数值结果分析;研究综合管廊与基坑距离对基坑土体位移场、综合管廊位移和变形、综合管廊周围土体应力分布的影响. 结果表明:坑外地表沉降的影响范围不超过12 m,最大沉降位于坑外4.5 m处,基坑开挖引起的综合管廊最大水平位移和竖向位移均未超过规范的预警值;综合管廊与基坑距离和综合管廊水平位移近似成反比关系;综合管廊发生朝向基坑一侧的倾斜,倾斜度随着综合管廊与基坑距离的减小而增大;综合管廊两侧墙产生朝向基坑的水平推力使综合管廊产生朝向基坑的变形和水平位移.

Effects of Foundation Pit Excavation With Inclined Support on Nearby Utility Tunnel

Taking the foundation pit excavation project near an existing utility tunnel in Xiamen City, Fujian Province as an example, aiming at the SMW construction method pile and inclined support system, 3D numerical model of the utility tunnel is established by FLAC3D finite difference software, and the numerical results are analyzed, and the effects of the distance between the utility tunnel and the foundation pit on the displacement field of the foundation pit soil, the displacement and deformation of the utility tunnel, and the stress distribution of the soil around the utility tunnel are studied. The results show that the influence range of the surface settlement outside the foundation pit is lessn than 12 m, the maximum settlement is located at 4.5 m outside the foundation pit, and the maximum horizontal displacement and vertical displacement of the utility tunnel caused by the foundation pit excavation do not exceed the warning value of the specification. The distance be-tween the utility tunnel and the foundation pit is approximately inversely proportional to the horizontal displacement of the utility tunnel. The utility tunnel inclines towards the foundation pit, and the incline degree increases with the decrease of the distance between the utility tunnel and the foundation pit. The horizontal thrust of the walls on both sides of the utility tunnel towards the foundation pit causes deformation and horizontal displacement of the utility tunnel towards the foundation pit.