岩石剪切裂隙渗流特性试验与理论研究

 通过在三轴应力条件下对丹江口库区辉绿岩进行剪切破坏得到剪切裂隙，然后对剪切裂隙进行不同围压和裂隙水压力(渗透压差)作用下渗透性能的试验研究。研究结果表明：绝大部分岩样在剪切破坏后会形成单条贯穿剪切裂隙，这种剪切裂隙的渗透系数与净围压的关系符合指数函数特征，且受环向应变影响很大，但受轴向应变影响较小；裂隙水压力对裂隙渗透系数影响明显，在相同净围压下，裂隙水压力越大，渗透系数越大，其主要原因是较大的裂隙水压力使裂隙两侧基岩产生附加变形，导致隙宽增加。基于试验数据和理论分析，根据三维应力下的裂隙–岩块位移模型推导考虑裂隙水压力的渗透系数计算公式，该公式可以较好地描述不同围压和裂隙水压力下实测渗透系数的变化趋势，并且公式中的参数均可根据简单的三轴压缩试验得到，计算结果与实测数据符合较好。

TEST AND THEORETICAL RESEARCH ON PERMEABILITY CHARACTERISTICS OF SHEAR FRACTURE IN ROCK MASS

Under the triaxial stress state,a shear fracture of the diabase samples from Danjiangkou reservoir is obtained by shear failure. Permeability tests under different confining pressures and fracture water pressures(i.e. permeability pressure gradients) are carried out to study the permeability characteristics of the shear fracture. The test results show that overwhelming majority of the rock samples produces a single running-through fracture after shear failure,of which the permeability coefficient decreases with the increase of net confining pressure,following the law of exponential function. The effect of axial strain on the permeability coefficient of rock samples is relatively weak,while the circumferential strain has strong influence on it,as well as the fracture water pressure. The permeability coefficient of fracture increases with the increase of fracture water pressure while the net confining pressure is the same,which is mainly for the additional compressive deformation of the rock matrix caused by the comparatively big fracture water pressure that leads to the widening of fracture aperture. Based on test data,theoretical analysis and the displacement model of fracture and rock under three-dimensional stress condition,a formula for permeability calculating is obtained with the effect of fracture water pressure taken into consideration. The formula corresponds with the changing trend of permeability coefficient under different confining pressures and fracture water pressures fairly well;and all the parameters can be obtained by triaxial compression test simply. The calculated and measured values of permeability coefficient of fracture match with well each other.