中文摘要：

深埋大断面隧洞开挖同时揭露多种不同岩性的岩体，各岩体之间物理力学性质差异大，其破坏规律也不相同。深入研究复杂岩性挤压破碎带的塌方演化过程及机制，对于防塌和治塌具有重要作用。针对锦屏地下实验室二期中3^#实验室的复杂岩性挤压破碎带区塌方，通过现场地质调查及矿物分析，发现该处破碎带本身岩性复杂、地应力高是影响这次塌方的关键因素。同时结合现场录像观察的塌落岩体破坏形态、室内电镜扫描结果和不同岩性岩体的空间分布特点，认为此次塌方具有明显的渐进性破坏特征；不同岩性岩体具有不同的破坏机制：南侧边墙和掌子面分布的花斑角砾状大理岩、溶蚀状大理岩为剪切滑移型破坏，北侧边墙方解石化大理岩为节理张开倾倒破坏，项拱镶嵌组合胶结状大理岩、花斑角砾状大理岩和溶蚀状大理岩为重力型塌落破坏。基于现场录像观察到塌方发生时间的先后顺序和电镜扫描不同岩性岩体的破坏机制，归纳其演化过程为：开挖卸荷→隧洞周边薄层岩体松散垮落→南侧边墙岩体剪切滑移破坏→北侧边墙岩体节理张开倾倒破坏→在两侧边墙卸荷作用下顶拱岩体发生卸荷回弹→重力坍塌破坏。根据岩体破坏机制和塌方演化过程，建议采用围岩表面和内部综合治理的支护措施（初喷不少于10cm厚的混凝土＋带锚垫板的注浆锚杆＋挂网＋复喷混凝土）。该研究成果可为深埋隧洞穿越复杂岩性挤压破碎带的类似设计、施工、支护提供参考。

英文摘要：

The excavation of deep buried tunnel with the large cross section reveals many kinds of rocks with different physical and mechanical properties. It is very important to study the process and mechanism of the collapse for the complex lithological compressive rupture zone. The complicated lithological compressive rupture is located in No.3 laboratory of Jinping underground laboratory. The collapse happened there once. It was found through the field geological investigation and mineral analysis that the complex lithology of rock mass and high in-situ stress were the key factor of collapse. The failure mode of rock collapse recorded by video, the failure mechanism obtained by scanning electron microscope and the different lithological rock mass located in spatial distribution indicated that there was an obvious progressive failure characteristics in this collapse and the different lithological rock masses exhibited the different failure mechanisms. The variegation breccia and the corrosion marbles in the southern side wall and tunnel face exhibited the shearing slip failure, and the calcite marble in the northern side wall exhibited the toppling failure due to joint opening, and the mosaic cementation marble, variegation breccia marble and corrosion marble in top arch exhibited the gravitational collapse. The process of collapse recorded by video and the failure mechanism of different lithological rock mass obtained by SEM show： the excavation unloading→the collapsing of the thin layer rock mass around the tunnel→the shearing slip of the rock in the southern wall→the toppling failure of rock in the northern wall due to joint opening→the rebounding of the top arch rock under the unloading of both sidewalls→the gravitational collapsing. The comprehensive treatment measures inside and outside of surrotmding rock（initial shotcrete not less than 10 cm thick ＋ grouting bolt with anchor plate ＋ suspended net ＋ shotcrete again） were recommended.