考虑管片环向接头效应的盾构近距离施工影响分析

Influence of Short-distance Shield Tunnel Construction Considering a Circumferential Joint Effect

由于受地质条件和施工水平的制约,新建盾构隧道近距离穿越既有隧道施工过程中,除引起地表沉降外,对既有隧道也将产生不利扰动影响。针对新建盾构隧道近距离垂直下穿既有运营隧道施工形式,重点考虑盾构管片环间接头非线性特征,构建三维弹塑性有限元模型,对穿越施工进行全过程模拟,对比分析盾构隧道近距离穿越施工引起既有隧道的受力和变形,并基于弹性铰接圆环模型,结合隧道结构力学理论计算方法对数值模拟结果进行比较验证。研究表明:盾构穿越施工期间,既有隧道顶部和底部的变形量均呈增大趋势,加入螺栓之后的既有隧道变形较均匀;既有隧道底部的变形增幅相对顶部变形偏大,管片环间加入螺栓时,既有隧道顶部和底部的变形大小趋于接近。

When the existing tunnels are traversed by the newly-built tunnel,not only the ground settlement will be caused,but also an adverse effect will be made on the existing one due to the constraints of geological conditions and construction level. For the construction form of the newly-built shield tunnel under-crossing the existing operating tunnel,considering the nonlinear characteristics of shield segment ring joint,the 3D elastoplastic FEM was applied to simulate the dynamic construction process,and the stress and deformation of the existing tunnel caused by shield tunnel construction with a short distance were compared. The numerical simulation results were compared with the theoretical calculation method of the tunnel structure based on the elastic hinge ring model. The results showed that the settlement of both the top and the bottom of the shield tunnel during the construction was an increasing trend. The deformation of the existing tunnel was more uniform when the bolt was added. The deformation at the bottom of the existing tunnel was relatively larger than at the top of the deformation. When the segment rings with bolts,both the top and bottom of the tunnel deformation tended to be similar.