Abstract: Based on the monitored microseismic data in situations with high geostress， large diameter， frequent daily blasting and strong blasting disturbance， the distribution of microseismic events occurring in the deep tunnels of JinpingⅡhydropower station under the action of blasting disturbance was investigated. The results show that the microseismic activities in the areas affected by excavation unloading are closely related to surrounding rock stress redistribution and blasting disturbance. And blasting disturbance is a main factor of triggering microseismic activities outside the influence range of excavation unloading; hence it is one of important factors for triggering the timedelayed rockburst. Moreover， the distribution area of microseismic events is associated with its distance from the sites where blasting events happen and the relative location between them. The results achieved can provide the reference for the rockburst prevention during deep tunnel excavation by drillandblast technique.

Key words: blasting disturbance, deep tunnel, microseism distribution, rockburst, surrounding rock stress