大岗山水电站厂房断层控制区域微震监测分析

大岗山水电站地下厂房断层发育，两条陡倾角断层穿过厂房中后部，控制着厂房的围岩稳定性。拱顶处发育的断层由于开挖而出现塌方，需要对塌空区以及地下厂房进行稳定性监测。2010年10月建立南非综合微震系统（ISS）微震监测系统，对断层控制的厂房区域进行微震监测。采用能级分布法、时空分布法、能量指数法、位错法等对断层控制下的塌空区、厂房边墙、断层周边岩体进行了稳定性评价。监测表明，塌空区微震事件少，能级小；边墙岩体位移较小，微震事件数目较少；断层面间滑动位移分布不均，整体位移量不大，断层面岩体活动性不强。因此，断层区域在进行加固后，岩体整体稳定性有所提高，受断层影响较小，故地下厂房稳定性较好。微震监测对水电厂房开挖及运行期的安全稳定性评价有较强的指导意义。

Analysis of monitoring microseism in areas controlled by faults near powerhouse in Dagangshan hydropower station

Many faults propagate near the underground powerhouse of Dagangshan power station. Rockmass stability of the underground powerhouse is controlled by two steep angle faults which are extended through the middle and rear parts of the powerhouse. The collapse area near the fault was found when the fault extended through the vault was excavated. So it is necessary to monitor the stability of the powerhouse and collapse area near the faults. The integrated seismic system(ISS) of South Africa is established to monitor the area in October 2010. The unattended system run automatically, which also can be controlled and diagnosed remotely. Four methods such as spatiotemporal distribution method, magnitude level method, energy index method and dislocation method are used to analyze the stability of the collapse area, side walls and the rock mass near the structure plane. The research results show that the underground plant is overall stable and safe. Few seismic events and low magnitude near the collapse area can be got from seismic monitoring data. Two side walls are stable because the number of the seismic events and dislocation slip of the rock mass are small. The slide displacement between the structural planes is scattered and small. And the rock of the fault plane is inactive. Therefore, the stability of collapse area is increased and less influenced by faults after the rock is reinforced by the anchor. It is of guide significance to use microseismic monitoring to assess the stability of power house during the running and construction stages.