白鹤滩水电站左岸主厂房洞室稳定性及主要变形破坏模式分析研究

Research on the Stability and Main Deformation Failure Mode of the Main Plant in the Left Bank of Baihetan Hydropower Station

白鹤滩水电站左岸主厂房规模庞大、结构形式及地质条件复杂、构造应力水平高。洞室开挖使受到高地应力脆性玄武岩在顶拱、拱脚处产生片帮破坏、主厂房岩壁梁围岩大变形、软弱层间错动带C2导致块体失稳等岩体稳定性问题。针对主厂房片帮破坏现象,采用岩石力学试验、声发射试验,与现场地质勘查结果对比,总结出主厂房片帮发生的一般性规律;针对主厂房岩壁梁围岩大变形现象,采用现场监测与Midas数值模拟(Hoek-Brown破坏准则)相结合方的法进行对比分析,总结出主厂房岩壁梁围岩变形量与岩体质量的好坏、断裂构造的发育程度有很大的关系;针对洞室开挖导致边墙块体失稳破坏问题,采用机制分析结合现场调查,得出上、下游边墙处形成的浅层块体的破坏规律。

The main powerhouse on the left bank of Baihetan Hydropower Station is large in scale,complex in structure and geological conditions,and with a high tectonic stress level. The excavation of the cavern is caused by the failure of the highland stress brittle basalt at the top arch and arch foot,the large deformation of the rock wall rock of the main powerhouse and the stability of the rock mass caused by the C2 block between the weak layer and the fault zone. Based on the rock mechanics test,acoustic emission test and the results of the site geological exploration,the general rule of the main building block is summed up in view of the failure phenomenon of the main building block. In view of the large deformation phenomenon of the rock wall rock in the main building,the field monitoring is combined with the Midas numerical simulation（ Hoek-Brown failure criterion）. The method is analyzed. It is concluded that the deformation of rock wall rock in the main building is closely related to the quality of rock mass and the development degree of fracture structure. In view of the problem of instability and failure of the wall block caused by the excavation of the cavern,the failure rules of the shallow block formed by the upper and lower wall of the wall are obtained by the mechanism analysis and the field investigation.