活动断裂带结构分区对隧道错断变形特征的影响机制

Influence Mechanisms of Structural Zoning of Active Fault Zones on Dislocation and Deformation Characteristics of Tunnel Liners

摘要:

活动断裂带产生的永久位移会导致穿越其中的隧道衬砌发生严重变形。为了探究断裂带内部结构分区对隧道衬砌错断变形的影响，总结归纳了一种包括上下盘、破碎带、断裂带核部和破裂面的断裂带错断概化模型，通过改变断裂带不同区域岩体力学参数、断裂带不同区域宽度以及破裂面出现位置，开展围岩?衬砌隧道的数值试验，测算纵向位移梯度、纵向位移曲率和椭圆度来表征纵向剪切变形、纵向弯曲变形和横断面变形。研究衬砌的纵向变形和横断面变形规律，揭示错断作用下断裂带结构分区对隧道衬砌变形的控制机制。结果表明：（1）断裂带错动作用下，衬砌纵向位移曲线呈“S”型，大部分位移集中在断裂带核部。断裂带核部的剪切变形大于其它区域，峰值发生在破裂面处，弯曲变形主要发生在岩体软硬交界面附近；（2）衬砌横断面变形由隧道纵向的剪切和弯曲共同作用产生，断裂带核部处的变形显著大于破碎带，破裂面附近和软硬岩体交界区域需重点关注；（3）分区岩体软硬程度差距越大和断裂带核部宽度占断裂带总宽度越小时，断裂带核部区间内衬砌纵向变形与横断面变形越剧烈。当破裂面发生在断裂带核部中央时，衬砌纵向变形与横断面变形最剧烈，而破裂面处于断裂带核部与破碎带分界面处， 破裂面导致的破坏范围有所增加。

Abstract:

Permanent displacement caused by active fault zones can lead to serious deformation of tunnel liners passing through them. To explore the influence of internal structural zoning of fault zones on the dislocation deformation of tunnel liners, this study summarized a generalized model for fault zone dislocation including the hanging wall, footwall, fracture zone, fault zone core, and rupture surface. By changing the mechanical parameters of rock mass in different zones of the fault, the width of different fault zones, and the location of the rupture surface, numerical experiments on the surrounding rock-tunnel liner were conducted. The longitudinal displacement gradient, longitudinal displacement curvature, and ellipticity were measured to characterize longitudinal shear deformation, longitudinal bending deformation, and cross-sectional deformation. The longitudinal and cross-sectional deformation patterns of the liner were investigated, and the controlling mechanisms of fault zone structural zoning on tunnel liner deformation under fault dislocation were revealed. The results showed that: (1) under fault zone dislocation, the longitudinal displacement curve of the liner exhibited an "S" shape, with most displacements concentrated in the fault zone core. The shear deformation in the fault core zone was larger than that in other zones. The peak value occurred at the rupture surface, and the bending deformation mainly occurred near the interface between soft and hard rock masses. (2) The cross-sectional deformation of the liner was caused by the combined action of longitudinal shear and bending. The deformation in the fault zone core was significantly larger than that in the fracture zone. Special attention should be given to areas near the rupture surface and the interface between soft and hard rock masses. (3) The larger the difference in hardness between soft and hard rock masses in different zones and the smaller the ratio of fault core width to the total fault zone width, the more severe the longitudinal deformation and cross-sectional deformation of the liner located in the fault zone core. When the rupture surface occurred at the center of the fault zone core, the longitudinal deformation and crosssectional deformation of the liner were the most severe. When the rupture surface was located at the interface between the fault zone core and the fracture zone, the damage range caused by the rupture surface increased.