锚固围岩流变特性与隧道衬砌压力演化规律研究

Research on the Rheological Properties of Bolted Rock and Evolution Law of Pressure on Liner

安装锚杆是解决软岩隧道大变形的有效手段之一。为进一步探讨锚杆对隧道的支护效用,本文基于Burgers模型,建立了可描述锚固岩体流变特征的宏观力学模型。以围岩锚杆耦合模型为基础,推导了在锚杆支护作用下隧道位移和衬砌压力的解析解。并利用数值模拟,验证了理论解答的可靠性。通过对锚杆参数的分析表明:锚杆的安装能有效地减小由于围岩流变导致的作用在衬砌上的形变压力与隧道位移。锚杆的支护效果与锚杆的参数密切相关。在锚杆参数值处于较小水平时,随着锚杆参数的增大,衬砌受力状态的改善效果十分显著;但当参数达到一定值后,这种改善效果的加强越来越不明显。因此,在隧道支护中,锚杆的设计参数存在最优值。

Installing rock bolts is one of the most effective methods to deal with large deformation occurring in soft rock tunnels. In this paper,the supporting effect of rock bolts on tunnel was discussed. Based on the typical Burgers model, a surrounding rock-bolt coupling rheological model was established in order to describe the macroscopic deformation behavior of bolted rock mass. Analytical solutions in closed form for the displacement and liner pressure in a circular tunnel considering the effect of bolt reinforcement were derived by use of the surrounding rock-bolt coupling rheological model. Then the numerical calculation was carried out to verify the effectiveness and reliability of theoretical analysis. Furthermore,a parametric analysis of rock bolts was performed and it could be concluded that installing rock bolts could dramatically reduce tunnel displacement and liner pressure exerted by timedependent deformation of surrounding rock. The supporting effect of rock bolts is closely associated with rock bolt parameter. It could be found that when rock bolt parameter varies in a relatively low level,the improvement of stress condition of liner is very significant as rock bolt parameter increases. However if rock bolt parameter reaches a certain value that is so-called the threshold,it will not show obvious change. Therefore,the design parameter of bolt proves optimal value in tunnel engineering.