侵入岩蚀变带软岩隧道大变形规律与稳定性研究

Study on Large Deformation Law and Stability of Soft Rock Tunnels in Intrusive Rock Alteration Zone

以安定隧道为工程背景,采用三维离散元方法对侵入蚀变岩破碎软弱围岩段隧道开挖大变形进行了数值模拟计算,分析了开挖进尺、台阶长度、台阶高度、裂隙密度等对隧道变形的影响规律,确定了台阶法施工时开挖参数的合理范围:开挖进尺为0.5~1.0 m、台阶长度为4~6 m、台阶高度为0.3 H~0.4 H。通过芬纳公式和卡斯特耐方程对隧道极限容许位移公式进行了修正,实践证明改进后的方法对隧道围岩稳定性判别更合理。

Taking Anding Tunnel as the engineering background,the 3D discrete element method is adopted to carry out numerical simulation calculations on the large deformation of tunnel excavation in the broken soft surrounding rock section of intrusive altered rock.The influence rules of excavation footage,bench length,bench height,crack density,etc.on tunnel deformation are analyzed.During the construction of the bench method,the reasonable range of excavation parameters is determined as follows:excavation footage is 0.5~1.0 m,bench length is 4~6 m and bench height is 0.3H~0.4H.The formula of the ultimate allowable displacement of the tunnel is modified by Fenner formula and Kastner equation,practice proves that the improved method is more reasonable to identify the stability of the surrounding tunnel rock.