Numerical Simulation and Analysis Method of Seismic Response for Hydraulic Tunnel across Fault

DOI：

 作者 单位 刘国庆1，肖明1?覮，杨阳2，任俊卿1 （1.武汉大学 水资源与水电工程科学国家重点实验室，湖北 武汉 430072； 2. 长江勘测规划设计研究有限责任公司，湖北 武汉 430010）

断层破碎带是影响高地震烈度区隧洞结构稳定的关键因素之一.针对地震作用下围岩与断层动力相互作用特点，建立了一种考虑多种接触状态的动接触力算法.该算法考虑了有限元模型中的点对接触和点面接触两种接触类型，可以模拟围岩与断层之间的黏结接触、静接触、分离和滑动接触4种接触状态，适合研究地震作用下围岩与断层动接触系统的非线性大滑移问题.首先，通过一滑块算例，验证了该算法的合理性.然后将此算法应用于滇中引水工程香炉山隧洞抗震稳定计算，对比分析了无断层，有断层、不考虑动接触，有断层、考虑动接触3种工况对隧洞地震响应的影响.结果表明，断层破碎带的存在加剧了隧洞的地震反应，主要表现为衬砌位移和应力的增加，以及围岩破坏区的扩大；考虑动接触后，围岩与断层在地震加载过程中，出现了明显的错动位移，进而对衬砌产生破坏作用；衬砌损伤区主要分布于断层穿过的部位及断层两侧约10 m范围内，其中上盘衬砌受断层影响较大；在横向地震动激励下，衬砌腰拱的应力和位移明显大于顶拱和底拱，为衬砌结构的薄弱部位.

The fault fracture zone is one of the key influencing factors on the structural stability of a tunnel in high earthquake-intensity area. Aimed at dynamic interaction characteristics between surrounding rock and fault under seismic action，a dynamic contact force method considering various contact states was established. The method considers point-to-point contact and point-to-surface contact in finite element model， and it can simulate four contact states between the rock and fault: bonded contact， static contact，separation and sliding contact. Therefore，it is suitable to study the nonlinear large slip problem of dynamic contact system composed of the rock and fault under seismic load. First，the rationality of the method was verified by a sliding block example. Then， the method was applied to the anti-seismic stability calculation of Xianglushan tunnel in Dianzhong water diversion project. The influences of three working conditions on seismic response of the tunnel were contrastively analyzed: without fault， with fault but without dynamic contact，and with fault and dynamic contact. The results indicate that the existence of fault fracture zone aggravates the seismic reaction of the tunnel，which mainly appears as displacement and stress increase of the lining as well as failure zone enlargement of the rock. When considering the dynamic contact，the evident alternate displacement forms between the rock and fault during seismic loading procedure，and then exerts destructive effects on the lining. The damage zone of the lining mainly distributes in the place where the fault passes through and within about 10 m range of distance from both sides of the fault， and the lining in hanging wall is greatly affected by the fault. Under the motivation of horizontal seismic motion，the stress and displacement of the lining haunch are significantly larger than that of the top and bottom arch，so that the haunch is considered as the weak part of the lining structure.