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为探究深埋软岩隧道在开挖无支护阻力条件下的围岩安全性受剪胀软化效应的影响机制,基于修正Mohr-Coulumb强度准则(简称修正M-C准则)和增量型本构关系(即Levy-Mises本构关系),通过对轴对称隧道进行弹塑性求解,研究岩石剪胀效应对软岩隧道安全性的影响。依据算例,分析软化模量、内摩擦角和黏聚力等参数对隧道的安全解(如隧道塑性软化区和塑性残余区边界线以及原岩应力阈值)的影响。计算中对支护反力进行恰当处理,并考虑软岩隧道的特殊力学性质(即剪胀效应),所得结果不仅是对现有理论解的补充和完善,而且更加符合工程实际。
In order to explore the mechanism of surrounding rock safety under dredging and softening effect in the excavation of unsupported deep soft rock tunnel, based on the modified Mohr-Coulumb strength criterion (modified MC criterion) and incremental constitutive relation (Ie, Levy-Mises constitutive relation), the elasto-plastic solution of axisymmetric tunnels is used to study the effect of rock dilatancy on the safety of soft rock tunnels. According to an example, the influence of softening modulus, internal friction angle and cohesion on the safety solution of the tunnel (such as the boundary line of plastic softening zone and plastic residual zone and the original rock stress threshold) is analyzed. In the calculation, the proper supporting force is treated and considering the special mechanical properties of the soft rock tunnel (ie, the dilatancy effect), the results obtained are not only complementary and perfect to the existing theoretical solution, but also more in line with the engineering practice.