Abstract: Through the acoustic emission（AE）experiments on the failure process of burst-prone quartzitic diorites under one-cycle loading and unloading condition, the characteristics of spectrum of AE signal and the relations among AE counts, energy, AE rate, energy rate, strain and time were studied.The results show that the rock experiences an initial consolidation stage and a non- elastic stage.The acoustic activity is stronger under unloading than under initial loading condition and the unloading further promotes the instable deformation.Before the deformation, AE rate and energy rate sharply increase and in the loading-unloading-loading process, the main frequency of acoustic activity develops in a process of low frequency, medium frequency, high frequency and then sub-high frequency, which can be reference to the rock-burst prediction for this type of rockmass.

Key words: Rock burst, Loading and unloading, Acoustic emission, Spectrum analysis