静态库仑破裂应力对断层地震失稳过程影响的模拟研究

SIMULATION STUDY ON THE EFFECT OF STATIC COULOMB FRACTURE STRESS ON SEISMIC INSTABILITY OF FAULT

基于速率—状态依赖性摩擦滑动定律,建立断层黏滑模型,采用阶跃形式的应力扰动加载于断层模型上,利用Runge-Kutta数值积分方法,主要分析了应力扰动值的正负、大小和加载时间t0对断层滑移时间的影响。结果发现,当库伦破裂应力为常数,不论是正应力起主导作用还是剪应力起主导作用,对后续断层的作用几乎一样。静态应力扰动作用下断层的成核周期会发生提前或者延后,具体表现为:当库伦应力为正时引起断层的成核时间提前,且提前量小于原有周期值;库伦应力为负时引起时间延迟,且延迟时间不受原有成核周期限制。库伦应力扰动的幅值越大,引起的滑移时间改变量越大。成核时间提前量与应力扰动的加载时间有关,在前期施加同样大小的应力扰动,时间提前量呈现随加载时间增加而增加的趋势。

Based on the rate of state dependent friction law of sliding fault bond-slip model is set up,in the form of step disturbance load stress on the fault model,using Runge-Kutta numerical integral method,the stress disturbance value plus or minus,size and loading time t0 the impact on the time of fault slip is analyzed.The results show that when the Coulomb fracture stress is constant,whether the normal stress plays a leading role or the shear stress plays a leading role,the effect on subsequent faults is almost the same. Nucleation of fault disturbance under the action of static stress cycle will happen in advance or delay,it shows as following：when the Coulomb stress for timing caused by fault of nucleation time in advance,and people are less than the original cycle value; The Coulomb stress is negative and causes time delay,which is not restricted by the original nucleation period. The greater the amplitude of Coulomb stress disturbance,the greater the change of slip time. The nucleation time advance is related to the loading time of the stress disturbance,and the same amount of stress disturbance is applied in the early stage.