ABSTRACT
The underground caverns of Lianghekou hydropower station were characterized by their depth, high geo-stress and complicated surrounding geological conditions. To identify the excavation-induced damage zones and forecast deformation of surrounding rock masses, a high-resolution Microseismic (MS) monitoring system was adopted to conduct real-time monitoring of micro-fracture activity of surrounding rock mass. The spatiotemporal distribution of the evolution of MS events recorded in the aggregation areas was analyzed. The analysis results show that two MS event clustering zones were closely related to the blasting excavation disturbances of the omnibus bar caves and the working surfaces. Moreover, prior to deformation of the surrounding rock mass, MS events in clustering zone I increased and became rapidly concentrated, the apparent stress of corresponding MS events suddenly decreased, and the cumulative apparent volume increased dramatically. This phenomenon can be regarded as an index for forecasting the deformation of surrounding rock masses.
