脆性岩石破裂过程渗透性演化试验

Experimental Investigation on Permeability Evolution of Brittle Rock in Failure Process

为探讨脆性岩石变形破裂过程中渗透性的演化规律,利用电液伺服控制岩石力学试验系统(MTS815 02)对不同岩性的岩石进行了应力 应变全过程渗透试验·试验结果表明岩石的渗透率与其应力状态密切相关,岩石峰后的渗透率普遍远大于峰前,常在应力 应变曲线峰后区出现'突跳'现象,而造成这一现象的根本原因在于岩石内部细观结构的变化·并根据试验结果建立了峰值前后反映岩石结构变化特征的分段应力 渗透率关系方程,为建立描述岩石破裂过程应力 渗透率耦合数值模型提供了可靠的试验依据·

A large number of permeability tests of different brittle rocks were conducted using an electro-hydraulic servo-controlled MTS 815.02 testing machine to investigate the permeability evolution characteristics of brittle rock in compressive deformation and failure process corresponding to the complete stress-strain path. Laboratory tests showed that the permeability of brittle rock relates closely to the state of stress in rock and the permeability of brittle rock in post-peak stress-strain region is much higher than that in pre-peak stress-strain region. Moreover, the sharp increase or sudden jump of permeability frequently occurs in the post-peak stress-strain region due to the catastrophic changes of microstructure of rock in compression. Based on the experimental results of permeability evolution tests for different brittle rocks, the piecewise stress-permeability fitting curves for brittle rocks in compression were obtained to offer reliable experimental evidence for the numerical model of coupled stress-permeability regarding the permeability evolution of brittle rock in compressive failure.