深埋穿越破碎带隧道衬砌变形规律研究

为解决隧道穿越破碎带、断层等不良地质体时导致的隧道结构变形过大，甚至引起垮塌等事故的难题，通过对西南某深埋穿越破碎带隧道衬砌现场监测数据的分析，结合数值模拟试验，研究了该隧道衬砌拱顶下沉、周边收敛变形规律，并对二者进行了对比。结果表明： 该隧道工程Ⅳ级至Ⅴ级围岩过渡区发生不均匀沉降，Ⅴ级围岩相对Ⅳ级围岩沉降值大15 mm左右；隧道拱顶沉降量是周边收敛位移的1.25~1.75倍，即拱顶对不均匀沉降的敏感度大于周边，属于隧道结构薄弱部位。基于自主研发的双向滑移式物理模型箱，研究了不均匀沉降条件下衬砌结构变形特征，衬砌轴向变形过程大致可分为5个阶段： 弹性应变、土体压密—姿态调整、塑性应变、土体再压密—姿态再调整、断裂破坏，且拱顶轴向变形为拱腰轴向变形的1.75~2.45倍，说明拱顶沉降对围岩完整性的敏感度大于周边收敛，应重点做好拱顶的监测与防护。

Study on the Deformation Law of Deep buried TunnelLining Crossing Fractured Zone

When the tunnel crosses fractured zone and faults, overlarge tunnel structural deformation and even collapse often occur. As a result, the on site monitoring data of a deep buried tunnel lining crossing fractured zone in southwest China are analyzed. And based on numerical simulation experiments, the laws of tunnel crown settlement and peripheral convergence are studied, and comparison is made between the two laws. The results show: (1) Uneven settlement occurs to the transition zone between Grade Ⅳ and Ⅴ surrounding rocks, and the settlement of Grade Ⅴ surrounding rock is 15 mm larger than that of Grade Ⅳ surrounding rock. (2) The settlement of tunnel crown is about 1.25~1.75 times of the peripheral convergent displacement, which indicates that the sensitivity of the tunnel crown to the uneven settlement is greater than peripheral area, and the tunnel crown is the weak part of the tunnel structure. Based on the self developed two way sliding physical model box, the deformation properties of lining under the condition of uneven settlement are studied. The study results show that the tunnel lining deformation under uneven settlement can be roughly divided into five stages, i.e. elastic strain stage, soil compaction attitude adjustment stage, plastic strain stage, soil re compaction attitude adjustment stage, and fracture failure stage; the tunnel crown axial deformation of each section is about 1.75~2.45 times of the peripheral convergence, which also shows that the sensitivity of the tunnel crown to environmental variation is greater than that of peripheral convergence, and monitoring and protection should be carried out for tunnel crown.