裂隙岩体高压压水试验水．岩耦合过程数值模拟

Numerical simulation of hydro-mechanical coupling process of fractured rock mass during high pressure permeability test

为了解高压水渗流作用对裂隙岩体应力和变形的影响,结合黑麋峰抽水蓄能电站岩体高压压水试验的渗压及变形测试成果,采用多孔连续介质全耦合理论,研究了试验区岩体测点在压水孔加压和卸压过程中的孔隙压力和位移变化过程。通过对测点位移和渗压随时间变化过程的计算值和实测值对比研究,验证了所采用的水-岩耦合数值模型的合理性。研究表明:在压水孔内的水压力和岩体孔隙压力的共同作用下,岩体内的应力大幅度增加;压水过程中,岩体因渗流作用产生了较大的位移,停止压水后的一段时间内,由于岩体中还存在一定的孔隙水压力和水压力梯度,从而导致岩体内仍存在部分变形值,且该部分变形值并非是压水孔卸载后岩体内的塑性残余变形;高压水渗流作用下的岩体耦合效应对工程应力和围岩变形有重大影响,考虑水-岩耦合效应的岩体稳定性评价结果对工程设计更具指导意义。

In order to understand the influence of seepage under high pressure condition on stress and deformation of fractured rock mass, fully coupling model based on porous media mechanics is employed to study the variations of pore pressure and displacement of measuring point in rock mass during the experiment period, combined with measured data of pore pressure and displacement obtained in high pressure permeability test at Heimifeng pumped storage power station. The hydro-mechanical coupling model is validated by the comparison of calculated results of pore pressure and displacements with measured data. It also indicates that rock mass stress increases sharply under the effect of water pressure in water injected borehole and pore pressure in rock mass, During the experiment, it occurs larger displacement in rock mass due to the seepage. After stopping injection of water, the deformation remains due to the existence of pore water pressure and hydraulic gradient in rock mass. The part of deformation is not the plastic residual deformation of rock mass after the unloading of water injected borehole. Hydro-mechanical coupling effect of rock mass under high water pressure condition is obvious. The evaluated results of rock mass stability with the consideration of hydro-mechanical coupling effect have more significance for engineering design.