双断层错动作用下马蹄形隧道结构破坏影响分析

Analysis of Damage Effects of Horseshoe Shaped Tunnel under Double Fault Dislocation

我国地铁建设飞速发展,由于地层结构的复杂性,特定情况下地铁线路不可避免地穿越断层构造。针对双断层错动影响下地铁隧道力学响应,从断层面接触关系和衬砌-围岩接触关系入手,结合混凝土应力应变关系以及破坏准则,建立考虑双断层共同作用的地铁隧道三维有限元模型。着重研究双断层错动下(不同错距、间距以及倾角)的隧道位移响应规律、剪应力响应规律、衬砌开裂分布特征以及纵向衬砌结构设防分区长度等。研究结果表明:断层拉剪作用对地铁隧道衬砌结构造成的破坏范围、破坏程度均更大;随着错距的增大,衬砌严重破坏范围变化不大,主要集中在断层面附近;在断层破碎带宽度为30 m的条件下,双断层邻近距离进入120 m以内时,将会对隧道结构产生“叠加效应”影响,衬砌开裂连成整体危害更大;断层倾角越大,隧道衬砌纵向错动影响范围越小,严重破坏范围也更集中。

The rapid development of subway construction in China witnesses inevitable faults crossing by subway lines due to the complexity of stratum structure under certain circumstances.Aiming at the mechanical response of the subway tunnel under the influence of double faults,a three-dimensional finite element model of the subway tunnel considering the interaction of the double faults is established in view of the interaction of fault planes and the contact relationship between the lining and the surrounding rock based on the stress-strain relationship of the concrete and the failure criterion.The study focuses on the displacement response law,shear stress response law,lining cracking distribution characteristics,and the length of fortification zones of longitudinal lining structure under double fault dislocation(different distances,intervals,and inclination angles).The research results show that the failure range and degree of lining structure of subway tunnel caused by fault tension shear action are larger;with the increase of stagger distance,the serious damage scope of lining changes only a little and mainly concentrates near the fault plane;when the width of fault fracture zone is 30 m and the distance between two faults is less than 120 m,the tunnel structure will be affected by“superposition effect”,and the combination of lining cracks may cause even greater damages;the greater the inclination of the fault,the smaller the influence of the longitudinal displacement of the tunnel lining,and the more concentration of serious damages.