深埋隧道开挖围岩失稳突变模型研究

Surrounding rock instability based on catastrophe model of deep-buried tunnel excavation

在分析隧道开挖引起围岩失稳基础上,认为深埋隧道围岩的失稳是一种突发破坏现象,具有明显的非线性和不连续性质,主要表现在力学变形性质的不确定性、本构关系的非线性和破坏过程中的突变性。运用突变理论探讨了深埋隧道失稳的机制;根据总势能原理,建立了隧道失稳的尖点突变模型,导出了失稳的力学判据条件;并基于深埋隧道典型断面拱顶下沉量现场量测的数据,计算出拱顶下沉函数的各变量值,由各监测断面位移突变阀值来判别深埋隧道围岩的稳定性,分析结果与实际施工围岩情况一致。研究成果可为预防深埋隧道围岩失稳、采取合理的施工工艺和支护措施提供参考依据。

By analyzing surrounding rock instability caused by tunnel excavation, surrounding rock instability of deep-buffed tunnels is considered as a sudden failure phenomenon, which possesses nonlinearity and discontinuity obviously and shows the uncertainty of mechanical deformation property, nonlinearity of constitutive relationship and catastrophe of failure process. Based on the total potential energy principle, the cusp catastrophic model for instability and failure of deep-buried tunnel surrounding rock is established. Through the observed data of settlement values of typical section vault of deep-buffed tunnel and the sudden threshold values of displacement of each monitoring section, the variable values of vault settlement function are obtained, and the stability of deep surrounding rock in tunnel is decided. The result accords with surrounding rock of practical construction, it not only offers references for preventing instability and failure of deep-buffed tunnels, but also gives an important guidance for reasonable construction technique of supporting measures.