基于隧道断面相对变形率判定围岩稳定性的研究

Study on Stability of Surrounding Rock Based on the Relative Deformation Rate of Tunnel Section Area

目前常用的判定围岩稳定性手段主要是监测隧道特征点或测线位移,但这种监测方法评价围岩稳定性存在诸多弊端。为此,本文从应变能角度对隧道围岩系统势函数进行理论分析。首先推导了围岩4个分区的应力、应变及位移表达式,进而分析各个分区的应变能,据此建立了隧道围岩系统势函数,并根据软岩破坏时的全应力应变曲线特征,确立隧道围岩系统势函数尖点突变模型,提出了定量评价围岩稳定性的理论依据。利用数值模拟手段,分析了不同荷载释放系数下隧道围岩特征点或测线位移、隧道围岩系统势能、隧道断面相对变形率3类指标变化规律。根据尖点突变模型,利用3类指标对围岩稳定性做出定量评价,并对3类指标下围岩破坏时的荷载释放系数进行对比分析,探讨了利用断面面积相对变形率指标判定围岩稳定性的可靠性。

At present,the normal method to judge the stability of surrounding rock is monitoring the displacement of tunnel characteristic points.However,there are many disadvantages in this way.This paper analyzed the potential function of surrounding rock system based on the principle of the strain energy.At first,the expressions of stress,strain and displacement of four zones in surrounding rock was deduced.And then,the strain energy of each partition was analyzed.So the potential function of tunnel surrounding rock system was established,and the cusp catastrophic model was got according to the characteristics of the total stress-strain curve when soft rock was destroyed.Then a theory for evaluating of surrounding rock stability quantitatively was proposed.By using numerical simulation method,the variation rules of three kinds of indexes under different stress release coefficients were analyzed,such as displacement of characteristic points or measured lines of tunnel surrounding rock,potential energy of surrounding rock and relative deformation rate of tunnel section.According to the cusp catastrophe model,the stability of the surrounding rock was quantitatively evaluated by using the three types of indexes,and the stress release coefficient was compared when rock was destroyed.And the reliability of the method was investigated,which assesses the stability of surrounding rock by relative deformation rate of section area.