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

摘要： 根据三轴压缩条件下岩石试件变形过程中多次重复发生的粘滑失稳事件,着重研究了突发失稳序列的演变特征及其影响因素。研究表明,随着错动量的增大,突发失稳的临界差应力和应力降呈现“正坡”、“负坡”和“平缓跳动”等阶段性变化,而应力降比率则渐趋减小；其变化原因主要与错动面的密接和凹凸程度、碎屑厚度、粒度、以及试件受力和刚度约束条件的改变等因素有关。突发失稳序列的变化特征,有可能为预测后续地震强弱变化的趋势提供依据。

关键词: 突发失稳, 临界差应力, 应力降, 特征错距, 地震复发