水库诱发地震的折迭突变模型

Fold Catastrophe Model of Reservoir-Induced Seismicty

基于库水在水库诱发地震中的重要作用,引入水致弱化函数Φ(ω).运用突变理论对走滑断层诱发水库地震的机制进行分析,建立了围岩-断层系统的折迭突变模型,分析了水库诱发地震的发生条件和过程,并给出了系统失稳破裂的临界条件.分析表明:水库诱发地震的临界条件是由围岩刚度与断层本构曲线的软化段斜率的绝对值的比值K确定,在库水的影响下,围岩刚度降低,断层本构曲线的软化段变陡,围岩-断层系统易达到K<1的临界条件,进而诱发水库地震.

A ＂water weakening＂ function,Φ（ω）, was proposed to predict the effect of water level on reservoir-induced seismic activity （RISA）. Catastrophe theory was used to analyze the mechanism of strike-slip fault movement during RISA. A fold catastrophe model for the rock- fault system surrounding a reservoir was established. RISA was predicted by the model and a critical condition where the system becomes unstable was noted. This critical condition is given by the ratio, K, of the stiffness to （the absolute value of） softness in the surrounding rock. Water in the reservoir reduced stiffness and the softening region of the constitutive curve becomes steeper. This makes it easy for the critical condition, K〈1, to occur. Hence, RISA is induced in the rock-fault system surrounding the reservoir.