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软弱围岩在隧道工程中经常遇到,它的空间大变形特征受台阶长度、台阶高度、工法及地应力水平等条件的影响。结合兰渝铁路两水隧道现场监测和数值模拟相结合的方法对软弱围岩隧道的空间变形特征进行了详细分析。研究结果表明:围岩越弱掌子面纵向挤出变形大小及变形速率越大,掌子面挤出变形受上台阶断面开挖高度和围岩级别影响较受台阶长度影响显著;在洞周先行变形中,拱顶下沉较水平收敛更加明显;初始地应力场应力水平增高,隧道掌子面挤出变形会大幅增加。研究结果可为指导隧道的施工和设计提供有效依据。
The weak surrounding rock is often encountered in the tunneling project. The large deformation of the surrounding rock is affected by the conditions of the length of the step, the height of the step, the working method and the stress level of the earth. Combining the on-the-spot monitoring and numerical simulation of two water tunnels in Lanzhou-Chongqing Railway, the spatial deformation characteristics of soft and weak surrounding rock tunnels are analyzed in detail. The results show that: the weaker the surrounding rock, the larger the longitudinal extrusion deformation and the rate of deformation, the extrusion deformation of the face is more affected by the excavation height and the grade of the surrounding rock than that by the step length; In the first deformation, the dome sinking is more obvious than the horizontal convergence; the initial stress field stress level increases, extrusion deformation of the tunnel face will increase significantly. The results can provide an effective basis for guiding the construction and design of the tunnel.