不同地应力场软岩隧道渐进破坏试验与分析

The test and analysis of progressive failure for soft-weak surrounding rock mass tunnel in different ground stress fields

针对软弱地层中常常发生的隧道塌方事故,以Ⅳ级围岩深埋公路隧道为对象,利用模型试验方法研究特定应力场下无支护隧道围岩的渐进破坏机理。采用弹塑性损伤本构模型,对模型试验工况进行有限元数值模拟,并在此基础上,对不同初始地应力场的情况进行扩展分析。研究结果表明:1)隧道开挖后围岩的破坏区主要集中在隧道拱顶上方,数值计算中用损伤变量最大值表示的破坏区与模型试验吻合较好;2)随着侧向压力系数的增大,松动破坏区面积随之扩大,且主要区域由隧道边墙两侧逐渐转变为隧道拱顶、拱底区域;3)随着侧向压力系数的增大,边墙水平收敛位移逐渐减小,拱顶收敛位移逐渐增大。

According to the common tunnel collapse inner soft- weak ground,the deep buried road tunnel with surrounding rock mass of grade Ⅳ was chosen as study object. The progressive mechanism of tunnel surrounding rock mass without support system was studied by model test. The case of model test was simulated by FEM with an elasto- plastic damage constitutive mode. On this basis,the cases of different initial ground stress field were carried out. The study shows that： 1） the main area of surrounding rock mass failure after tunneling is centralized above tunnel crown. The failure area denoted by maximum of damage variable in numerical calculation are similar with the results in model test. 2） With the increase of cateral pressure coefficients,the area of loose failure becomes more simultaneously,and the main areas gradually change from tunnel hances to crown and invert.3） With the increase of cateral pressure coefficients the convergence displacement of hance becomes less and the displacement of crown becomes larger.