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Abstract Based on a series of triaxial cyclic loading-unloading and permeability tests，the damage evolution of granite under compressive stress condition and its impact on rock′s permeability are investigated. In this study，the conventional permeability test method is optimized by drilling two small boreholes from the sample surfaces，which allows measuring the permeability variation of rock sample with different failure modes. The testing data reveal that the damage evolution is initiated simultaneously with the appearance of microcracks，and accelerated in the failure and post-peak phases. A consistent tendency between the damage evolution and the accumulation of recorded acoustic emission(AE) events is noticed，which verifies that the initiation and propagation of the microcracks are the essential mechanism related to the degradation of mechanical behaviour of granite. The permeability is also mainly increased during the failure and post-peak phases，and its variation is found to be hysteretic compared to the damage evolution before rock failure. It means that the impact of damage evolution on permeability is limited before the coalescence of microcracks. With the increase of confining pressure，the permeability is decreased abruptly at first；and then the decreasing tendency becomes less pronounced when the confining pressure reaches a certain level. Based on the AE data，an empirical equation describing the impact of damage evolution and confining pressure on rock?s permeability is established.
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Received: 19 April 2013
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2014, Vol. 33 
