【摘要】 针对高地应力软岩隧道初期支护大变形力学机制研究的不足,以隧址区地应力最大主应力为水平方向,且与隧道轴线接近垂直的丽香铁路中义隧道为工程背景,通过现场监测资料的综合分析,得出了大变形区段初期支护变形、破坏的力学机制,并在此基础上提出了大变形控制措施。研究表明:在地应力最大主应力为水平方向且与隧道轴线垂直的条件下,初期支护表现出水平收敛大于拱顶下沉的变形特点,破坏形式以拱顶喷射混凝土剥落、掉块,边墙拱架压曲外鼓为主,初期支护边墙段既是受力最大的部位,又是变形最大的部位,应将其作为变形控制的重点部位;初期支护边墙段的变形、破坏经历两个阶段;第一阶段边墙受力以围岩的水平挤压应力为主,变形以水平向围岩压力作用下的弯曲变形为主;第二阶段边墙受力以竖向压力为主,变形以压弯共同作用下的压弯屈服破坏为主。更多还原

【Abstract】 Focusing on the lack of mechanical mechanism of large deformation of initial support for high ground stress soft rock tunnel, under the engineering background that the maximum principal stress of the geo-stress in the Zhongyi tunnel of Lixiang Railway is horizontal and near vertical to the axis of the tunnel, the mechanical mechanism of deformation and failure of the initial support deformation of the large deformation section was analyzed based on field monitoring data. Based on the mechanical mechanism, measures for controlling large deformation are proposed. The research shows that under the condition that the maximum principal stress of the geo-stress is horizontal and perpendicular to the tunnel axis, the horizontal convergence of initial support is greater than the settlement of vault. The main failure mode is the vault shotcrete peeled off and dropped, and the side wall arches necked-out. The initial support section of side wall under the maximum force and deformation, which should be taken as the key part of deformation control. The deformation and failure in the initial support section of side wall include two stages. The first stage is that the side wall is mainly subjected to the horizontal compressive stress of surrounding rock, and the main deformation is the horizontal bending deformation under the pressure of surrounding rock. The second stage is that the side wall is mainly subjected to vertical pressure, and the main deformation is compressive and bending failure.更多还原