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Abstract The microseismic monitoring system is the first time to be established in underground plants of Dagangshan hydropower station in China，which is composed of detector，data acquisition instruments，control and communication system and can be controlled from internet. A lot of seismic events data are processed and different methods are used to analyze the stability of the collapse area and the whole underground plant. First，the stability of rockmass near collapse area is estimated from the spatiotemporal and energy level distribution of seismic events. Second，three methods are used to estimate the overall stability of the powerhouse，such as energy index(EI) method，cumulated apparent volume(CAV) and EI method，Schmidt number and CAV method. Third，the magnitude of seismic events near the powerhouse can be predicted by analyzing the existing monitored data；and the safety evaluation method for underground hydropower plant is set up. The results show that the seismic events are active at the lower part of the plant，but the magnitudes are small and they are a bit far away from the powerhouse. There are less microseimic events near the collapse area after reinforced by shotcrete and anchor. So the underground powerhouse of Dagangshan hydropower station is overall stable. The establishment of safety evaluation method has a good guidance to the design and construction of underground hydropower plants.
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Received: 05 February 2012
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2012, Vol. 31 
