浅埋隧道开挖诱发上覆管道管底脱开范围求解及判定

SOLUTION AND DETERMINATION OF OVERLYING PIPE-SOIL VOID RANGE INDUCED BY SHALLOW TUNNEL EXCAVATION

  • 摘要: 由于土体的大变形特性及管土刚度差异过大造成浅埋隧道施工时上覆管道与周围土体的脱开现象广泛存在。该文基于管道的变形分析提出浅埋隧道开挖诱发上覆管道管土脱开区的求解方法。以高斯曲线分布模拟土体变形,并基于可考虑地基连续性与非线性的Pasternak地基修正模型,分别建立浅埋隧道施工下穿管土协调区与脱开区的微分控制方程,进而利用有限差分法与牛顿迭代法得到隧道开挖诱发上覆管道竖向变形数值解,由此根据管土的位移差给出脱开区大小迭代求解步骤。提出可综合考虑管道刚度与土体强度的管土相对刚度参数R及综合考虑土体荷载特性的脱开荷载比参数Tg,将其作为管土脱开的判定参数。结合工程案例监测数据、已有模型试验数据验证了方法的正确性。管道归一化竖向位移值对比分析表明,存在临界管土相对刚度及临界且脱开荷载比参数,当R大于临界相对刚度或Tg小于临界荷载比时管土存在脱开现象,此时管道变形计算需考虑管土脱开效应。该结论可供工程设计参考。

     

    Abstract: Due to the large deformation of soil and the large difference in the stiffness of pipe and soil, the separation of the overlying pipes and surrounding soils are widely observed during the construction of shallow buried tunnels. Proposing a method for solving the soil release zone of overlying pipeline induced by shallow buried tunnel excavation based on the analysis of pipeline deformation. The Gaussian curve distribution is used to simulate the soil deformation. Based on the nonlinear Pasternak foundation correction model, which can consider the continuity and non-linearity of the foundation, the differential governing equations of the coordination zone and the detachment zone of the pipe-soil under shallow buried tunnel construction are established, respectively. The numerical solutions of the vertical deformation of the overlying pipeline induced by tunnel excavation are obtained using the finite difference method and the Newton iteration method. According to the displacement difference of pipe-soil, the size of the release zone is solved iteratively. The relative stiffness parameter R of pipe soil, which can comprehensively consider pipe stiffness and soil strength, and detachment load ratio parameter Tg, which comprehensively considers soil load characteristics, are proposed as the judgment parameter of detachment of pipe soil. The proposed method was verified using the monitoring data of engineering cases and the existing model test data. The comparative analysis of the normalized vertical displacement of pipeline shows that there are critical relative stiffness of pipe-soil and critical and detachment load ratio parameters. When R is greater than the critical relative stiffness or Tg is less than the critical load ratio, the detachment effect of pipe-soil should be considered in the calculation of pipeline deformation. This conclusion can be used as reference for engineering design.

     

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