基于块体离散单元法的走滑型活动断裂错动作用下隧道结构响应

Response of Tunnel Structure under Strike-Slip Active Fault Dislocation Based on Block Distinct Element Method

以某穿越走滑型活动断裂带隧道为工程背景,采用离散单元法建立“围岩-衬砌-断裂带”三维块体离散单元模型,分析不同错动量作用下隧道衬砌整体位移响应;明确统一的隧道复合式衬砌结构位移及类圆形断面变形损伤控制标准,分析走滑型活动断裂错动作用下沿隧道纵向位移变化和横断面上径向变形损伤规律,并对比3种断面预留位错空间方案下的衬砌响应规律。结果表明;隧道衬砌的显著性位移和径向变形率最凸出区间均主要集中在断裂带及其两侧附近,拱顶竖向位移向下呈“V”形,仰拱底部竖向位移向上呈倒“V”形,左右拱脚水平位移方向均与断裂错动方向一致,呈“S”形;随着错动量的增加,衬砌节段间差异位移不断增大,断面上拱顶和仰拱底部变形最为严重;随着断面预留位错空间的增加,衬砌位移极值不断增大,但断裂带两侧隧道衬砌影响范围基本不变,断面上部分关键部位之间损伤破坏临界错动量减少,不利于隧道结构抗错。

Taking a tunnel crossing strike-slip active fault zone as the engineering background,a 3D block discrete element model of“surrounding rock-lining-fault zone”was established by distinct element method,and the overall displacement response of the tunnel lining under different dislocation momentum was analyzed.A unified control standard of structural displacement and deformation damage of quasi-circular cross-section for tunnel composite lining was established,and the variation of longitudinal displacement along tunnel and the damage law of radial deformation on the transverse cross-section under strike-slip active fault dislocation were analyzed.Meanwhile,the lining response laws under three schemes of reserved dislocation space on the crosssections were compared.The results show that the significant displacement of the tunnel lining and the most protruding interval of the radial deformation rate are mainly concentrated at the fault zone and its vicinity on both sides.The vertical displacement of the vault presents a“V”shape downward,the vertical displacement of the invert bottom presents an inverted“V”shape upward,and the horizontal displacement direction of the left and right arch feet is consistent with the direction of the fault dislocation,presenting an“S”shape.With the increase of dislocation momentum,the differential displacements among lining segments increase,and the most serious deformation on the sections occurs at the vault and the invert bottom.As the reserved dislocation space of the sections increases,the extreme value of lining displacement is increasing,but the influence scope of the tunnel lining at both sides of the fault zone barely changes,and the critical dislocation momentum of the damage and failure between some key parts on the sections is reduced,which is unfavorable for the anti-dislocation of tunnel structures.