乌东德水电站右岸地下厂房开挖围岩破坏模式及形成机制研究

 乌东德水电站右岸地下厂房洞室群布置复杂，中低应力条件下，“陡倾、小夹角”等不利岩层产状导致结构面控制型破坏现象突出。结合地质、现场勘查、常规监测、微震监测及数值模拟资料，全面总结和分析右岸厂房下游拱座岩体破坏模式及形成机制。首先，基于现场勘查及常规监测资料，归纳和总结围岩破坏的基本特征与规律，包括其破坏形式、空间位置、破坏规模、破坏发展特征等主要信息；其次，总结岩体破坏孕育、发展过程中微震活动强度的时间演化规律，分析得到基于微震活动特征的层状岩体破坏前兆；最后，采用“微震监测”为主“数值模拟”为辅的综合分析手段，揭示下游拱座岩体发生弯曲倾倒的破坏本质及其形成机制，探讨岩体结构对拱座围岩破坏的力学影响机制。该研究可为陡倾层状岩体中大型地下洞室优化开挖方案和支护措施提供依据，也可为同类大型地下洞室相似围岩破坏的防控提供参考。

Failure mechanism and mode of surrounding rock of underground powerhouse at the right bank of Wudongde hydropower station subjected to excavation

The layout of the underground group caverns of Wudongde hydropower station at the right bank has a complicated form，and the structure-controlled failure phenomena occurred frequently due to the low stress condition and unfavorable formations of rock stratum，such as high dip angle and low strike angle. In this study，the modes and causes of failure of the surrounding rock near the downstream abutment of the main powerhouse at the right bank are systematically summarized with the geological data，field surveys，traditional monitoring，micro-seismic(MS) monitoring and numerical simulation. Firstly，the essential characteristics of the failure of surrounding rocks including the failure modes，spatial locations，scale of destruction and damage process，are summarized. Secondly，the temporal variation of the micro-seismic activity and the micro-seismic precursory characteristics of the failure of layered rock during the development of the studied failure are obtained. Finally，the flexural toppling failure of the surrounding rocks and the causes of this phenomena are revealed. The influence of rock structure on the failure of the surrounding rocks near the abutment is also discussed in detail by using a comprehensive method，which incorporates the micro-seismic monitoring and numerical simulation.