浅埋偏压软岩隧道数值模拟及方案比选

围岩的应力应变是分析隧道开挖中围岩稳定性的重要依据。目前比较成熟的隧道施工力学方法主要是对隧道开挖过程进行数值模拟。通过大型有限元软件ANSYS,计算了不同埋深、不同坡度角、不同覆盖层厚度条件下,马鞍形浅埋偏压软岩隧道围岩的应力应变,分析其规律并进行方案比选,确定了此类隧道比较合理的设计方案。分析结果表明:以2倍洞径的埋深作为偏压隧道深埋或浅埋的判断依据是合理的;在保证围岩稳定不发生片帮冒顶的前提下,减小埋深和覆盖层厚度是比较合理的;隧道内壁各点的应力应变规律可以为隧道开挖中支护结构参数的选取提供参考。

Numerical Simulation and Scheme Comparison of Shallow and Unsymmetrical Tunnel in Soft Rock

Stress-strain of surrounding rock is an important foundation for analyzing the stability of tunnel excavation. The mature tunnel mechanics is mainly to numerically simulate the tunnel excavation at the present. In this paper, with large finite element software ANSYS, stress-strain of surrounding rock of the saddle-shaped shallow tunnel excavation in soft rock of different depth, slope angle and covering layer thickness are calculated and analyzed, the laws are educed, the schemes is compared and the reasonable scheme is confirmed. The results show that: it is reasonable for 2 times of the tunnel depth as the judgment of deep or shallow unsymmetrical tunnel; it is reasonable to reduce the depth and covering layer thickness on the condition that surrounding rock is stable without wall spalling and roof caving. The laws of stress-strain of the surrounding rock internal wall in the tunnel excavation may provide reference to selection of the supporting structure parameter.