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近几十年来,国内外广泛研究了应力对岩石渗透性影响的重要科学命题,对于等效均质岩石而言,其结果主要表明轴向应力、侧向压力和体积应力对岩石渗透性有重要影响。剪应力的影响如何,有过许多讨论,但并无一致结论。以课题组进行的20余个矿井煤样三轴应力作用下的渗透率测试结果为基础,采用八面体剪应力表征剪应力,通过数据拟合的方法,给出了同时考虑体积应力、孔隙压力和八面体剪应力影响的公式,并与文献[11]仅考虑体积应力与孔隙压力影响的拟合结果比较,发现拟合公式增加八面体剪应力项,给出的拟合结果的复相关系数提高不大,平均仅1.06%,最高仅4.73%。充分说明对于等效连续介质而言,剪应力对渗透性的影响很小,主要是体积应力的作用,其机理是体积应力对孔隙大小的变化,而不是八面体剪应力对孔隙形状的改变。
In recent decades, the important scientific propositions on the influence of stress on rock permeability have been extensively studied both at home and abroad. For equivalent homogeneous rocks, the results mainly show that axial stress, lateral pressure and volume stress are important to rock permeability influences. There have been many discussions on the impact of shear stress, but no conclusion has been reached. Based on the test results of the permeability of more than 20 coal samples under the triaxial stress of the research group, the octahedral shear stress is used to characterize the shear stress. The data fitting method is used to calculate the influence of the volume stress, pore pressure And octahedron shear stress. Compared with the fitting results of literature [11], which only consider the influence of volume stress and pore pressure, it is found that the fitting formula increases the octahedral shear stress term and the complex correlation coefficient of the fitting result Little improvement, an average of only 1.06%, the highest only 4.73%. It is fully demonstrated that the shear stress has little effect on the permeability for the equivalent continuous media, mainly the effect of volume stress. The mechanism of volume stress is the change of pore size, rather than the change of pore shape by octahedral shear stress.