挤压流动性隧道底臌机理及控制技术

Mechanism and Control Technology of Extruding Flowing Floor Heave in Tunnel

为了从根本上防治隧道底臌和仰拱破裂,针对挤压流动条件下隧道底板变形破坏规律研究的不足,通过建立隧道侧墙岩体在支承压力作用下的力学模型,分析了侧墙岩体和顶、底板界面应力以及岩体轴力的基本分布规律,推导了侧墙岩体水平收敛位移及其极限平衡区宽度的理论计算公式。在此基础上,进一步分析了隧道底板岩体在侧墙岩体的挤压下产生塑性流动时的最大剪切破坏深度及其与相应侧墙的距离。最后以云岭隧道底臌为工程实例,对隧道侧墙和底板的初期支护参数进行了优化设计。分析结果表明:底板最大破坏深度及其与隧道侧墙的距离取决于侧墙岩体的极限平衡区宽度和底板岩体的内摩擦角;对于挤压流动性底臌,在加强地下水封堵和提高仰拱抗变形能力的同时,更应注重对隧道侧墙和底板岩体的锚注联合初期支护,为后续挤压流动性隧道底臌灾害的有效防治提供参考。

In order to prevent the floor heave and invert rupture of the tunnel fundamentally,for the lack of the study on the deformation and destruction law of the tunnel floor, the basic distribution of the stress on the interfaces between the sidewall and the roof or floor was analyzed, as well as the axial force of the rock on the sidewall according to the mechanical model of the sidewall under high bearing pressure. It derived theoretical formulas on the horizontal convergence displacement and the width of the limit equilibrium of the tunnel sidewall. On this basis,it discussed the maximum depth of the tunnel floor shear failure on the condition of the extrusion by the side wall of rock and the distance of the floor rock to the sidewall. Taking the extruding flowing floor heave in Yunling tunnel as an example, it optimally designed the initial support parameters of the sidewall and floor. The results indicate that the maximum depth and the distance depend on the width of the limit equilibrium of the sidewall and the internal friction angle of the floor rock. The control measures of the extruding flowing floor heave in tunnel are not only to enhance groundwater block and improve resistance to deformation of the invert, but also to set up the bolting and joint early support of the sidewall and floor of the tunnel. The results provide a reference for the effective prevention and treatment of the extruding flowing floor heave in tunnel.