盾构隧道曲线段掘进引发邻近地下管线变形分析

Research on deformation of adjacent underground pipelines caused by shield machine tunneling along curve section

城市中管线分布错综复杂,盾构隧道掘进易对管线造成扰动,导致管线变形甚至裂损。盾构机沿曲线段掘进时对周边环境的扰动更大,因此,明确盾构机在曲线段掘进时引发既有管线变形情况意义重大。将既有管线视为放置在Pasternak地基上的Euler-Bernoulli梁,基于镜像汇源法和Mindlin解,推导盾构机在曲线段掘进时引发既有管线变形的计算公式,根据实际工程案例构建对应的数值计算模型,分析盾构机沿曲线段掘进时引发既有管道的变形情况以及本文公式的适用性。研究结果表明:管道变形理论计算结果、数值模拟结果以及现场监测结果三者计算误差较小,验证了数值计算模型及理论公式的正确性;管道横向沉降槽呈非对称分布,靠近曲线内侧的管道变形大于曲线外侧管道变形;随着盾构机不断掘进,既有管线变形由轻微隆起转变为沉降,当盾尾通过管道后,管道沉降量达到最大值,管道的最大变形位置首先出现在管道中心位置,随后偏向弯道内侧,最终回归管道中心位置;转弯半径R对既有管线变形的影响较小,管线模量E以及隧道半径R对既有管线变形影响极大,管道最大沉降位置偏离管道中心线约0.5R。

The distribution of pipelines in cities is intricate and complicated, and shield machine tunneling may cause disturbances to the pipelines, resulting in pipeline deformation or even cracks. When the shield machine tunneling direction is along the curve section, the disturbance to the surrounding environment is greater. Therefore,it is of great significance to clarify the deformation of the existing pipeline caused by the shield machine during the tunneling of the curve. The existing pipeline was considered as a Euler-Bernoulli beam placed on the Pasternak foundation, then, the calculation formula for the deformation of the existing pipeline caused by the shield machine tunneling along the curve section was deduced based on the mirror image source method and Mindlin solution, and the corresponding numerical calculation model was constructed according to the actual engineering case. The deformation of the existing pipeline caused by the tunneling of the shield machine along the curve section and the applicability of the formula in this paper were analyzed. The results show that the theoretical calculation results,the numerical simulation results and the field monitoring results of deformation are in good agreement, which verifies the correctness of the numerical calculation model and theoretical formula. The transverse settlement troughs of the pipeline are distributed asymmetrically, and the deformation of the pipeline near the inner side of the curve section is greater than that of pipeline outside the curve section. With the continuous excavation of the shield machine, the deformation of the existing pipeline occurs from slight uplift to settlement. When the shield tail passes through the pipeline, the settlement of the pipeline reaches the maximum value. The maximum deformation position of the pipeline first appears in the center of the pipeline, then the position deviates to the inside of the curve section and finally returns to the center of the pipeline. The turning radius Rhas little effect on the deformation of the existing pipeline, the pipeline modulus E and the tunnel radius R have great influence on the deformation of the existing pipeline, and the maximum settlement position of the pipeline deviates from the centerline of the pipeline by about 0.5R.