关键词: 突发失稳, 临界差应力, 应力降, 特征错距, 地震复发

Abstract: The recurrence of stick-slip events along the sawcut or newly-created fracture zone in rockspecimens are carried out at confining pressures with the triaxial compression apparatus with solidmedia for studying the evolution characteristics of sudden-instability sequences and the effects ofvarious factors on them. The results indicate that, with increasing sliding displacement the critical differential stress level necessary for sudden instability and stress drop change successively bystages of“ascending-slope”,“descending-slope”and“flat-cum－fluctuation”,while the ratio ofstress drop to critical differential stress level tends to decrease. These evolutions are attributedmainly to the changes of the contact and asperity degrees of sliding zone,the thicknesses andgrain sizes of fragments within it,and the loaded and constrained conditions of specimen It isexpected that the characteristics of sudden-instability sequences revealed in this study would be aconceptual basis for predicting the tendency of ensuing earthquakes in their magnitudes,recurrence intervals and hypocenter offsecs.

Key words: Sudden-instability sequence, Critical differential stress level, Stress drop, Characteristic sliding displacement, Earthquake recurrencc