水渗透引起的应力场调整及岩石强度弱化的初步研究

本文采用二维线弹性的两相多孔介质理论,对水库蓄水后由水渗透引起的耦合应力变化及岩石强度弱化进行了数值模拟计算。结果表明,由于水的渗透使得岩石中的孔隙压力增大,耦合应力随之减小,从而导致岩石的有效应力减小,同时抗剪强度也相应减小,其减小的量值可以与地震时断层面上的应力降相比。根据计算结果,本文讨论了由水渗透引起地震的可能机制。

PRELIMINARY STUDY ON STRESS FIELD ADJUSTMENT AND ROCK STRENGTH WEAKENING CAUSED BY WATER SEEPING

In this paper, we make a numerical and simulant calculation of coupled stress and rock strength weakening caused by water seeping after reservoir impounding, using the theory of two-phase porous medium. The results show that due to water seeping, pore pressure in rock increases and coupled stress decraeses, so the effective stress in rock decreases and the shear strength should decrease. The decreasing increment is comparable to the value of the shear stress drop on seismic fault surface. Finally, some possible mechanisms about reservoir earthquake caused by water seeping are discussed.