深埋硬岩组合隧道围岩开挖变形影响研究

Study on the Effect on Deformation of the Surrounding Rock Induced by Deep-Buried Tunnelling under Hard Rock Combination Conditions

深埋硬岩顺层构造由于其分层特性和结构形式的特点决定了在这样的地质环境中开挖隧道时,围岩应力重分布造成的围岩变形和破坏具有一定的特殊性。文章以某高速铁路黄草隧道为工程案例,主要考虑硬岩层理与节理的影响,通过数值计算方法研究受开挖影响的围岩二次应力场的分布情况,同时对围岩的变形情况进行相应的评价。结果表明:(1)深埋隧道考虑层理和共轭节理共同作用时,变形方向主次不明显,环向位移呈非对称分布特征;(2)隧道埋深越大,开挖条件下洞壁变形越大,最大变形及云图范围发育在垂直层面方向;(3)层面共轭节理的存在大大降低了顺层隧道的非对称变形特性;(4)受水平构造应力场的影响,在最大水平主应力方向洞壁产生了较大的变形。

When a tunnel is located in deep-buried bedding hard rock structures,the rock deformation and failure caused by the stress redistribution have a certain level of particularities due to their stratification characteristics and structural forms.This paper takes the Huangcao tunnel on a certain high-speed railway as the engineering case,studies the distribution of the secondary stress field in the surrounding rock affected by excavation through numerical calculation,mainly taking into consideration the influence of hard rock bedding and joints,and evaluates the deformation of the surrounding rock accordingly.The results show that(1)when considering the interaction of bedding and conjugate joints in deep-buried tunnels,the primary and secondary deformation displacements are not obvious in terms of the direction,while the circumferential displacement is featured by asymmetric distribution;(2)the greater is the tunnel depth,the greater the deformation displacement of the tunnel walls will be under excavation conditions,and the maximum deformation and contour range are developed in the direction of the vertical plane;(3)the presence of conjugate joints greatly reduces the asymmetric deformation features of rocks in bedding tunnels;(4)under the impact of horizontal tectonic stress fields,larger deformation displacement is generated in the tunnel walls in the direction of the maximum horizontal principal stress.