Effect of shear displacement on the hydraulic conductivity of a fracture
Effect of shear displacement on the hydraulic conductivity of a fracture
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DOI：
10.1016/j.ijrmms.2009.10.002
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发表时间：
2010-04
影响因子：
7.2
通讯作者：
K. Matsuki;Y. Kimura;K. Sakaguchi;A. Kizaki;A. Giwelli
中科院分区：
文献类型：
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作者：
K. Matsuki;Y. Kimura;K. Sakaguchi;A. Kizaki;A. Giwelli
利用人造裂缝再现花岗岩中的拉伸裂缝，估计相对于宏观水流倾斜的剪切位移对岩石裂缝的水力传导性的影响。结果表明，平均孔径归一化的水力孔径随剪切位移方向与宏观水流方向夹角的增大而增大，并呈2倍夹角的正弦函数关系。根据本工作和以前的工作中得到的结果，建立了公式来估计作为平均孔径，初始孔径的标准偏差，剪切位移，剪切位移和宏观水流之间的角度的函数的断裂的水力孔径，但忽略尺度效应。在忽略尺度效应的前提下，根据花岗岩裂隙的实验结果，对裂隙的力学性质进行了假设，并对裂隙在应力状态（σ1= 29 MPa，σ2= 25 MPa，σ3=13.5MPa）下的渗透系数进行了估算。在应力主轴方向上，将裂隙的横向位移等值线图绘制在裂隙法线方向的立体网格上时，会出现一个脊线（局部最大值线），脊与σ3轴的倾角随剪切位移的增大而减小，因为剪切膨胀随着法向应力的减小和剪切位移的增大而增大。此外，在本研究所给应力条件下，对于垂直于σ2-σ 3平面内的裂隙，宏观水流沿σ 1方向的透过率最大，而对于垂直于σ1-σ 3平面内的裂隙，宏观水流沿σ 2方向的透过率最大。
The effect of shear displacement inclined relative to macroscopic water flow on the hydraulic conductivity of a rock fracture was estimated, using synthetic fractures that reproduce a tensile fracture in granite. The results showed that the hydraulic aperture normalized by the mean aperture increased with the angle between the directions of shear displacement and macroscopic water flow, according to a sinusoidal function of twice the angle. Formulae were established to estimate the hydraulic aperture of the fracture as a function of the mean aperture, the standard deviation of the initial aperture, the shear displacement, and the angle between the shear displacement and macroscopic water flow, based on results obtained in both this work and previous work, but neglecting scale effects. By assuming the mechanical properties of the fracture based on experimental results for granite, but neglecting scale effects, the hydraulic conductivity of the fracture with an arbitrary direction under a given state of stress (σ1=29MPa, σ2=25MPa and σ3=13.5MPa) was estimated for macroscopic water flow in the directions of both σ1and σ2. When the contour map of the transmissivity of the fracture is plotted on a stereonet of the normal direction of the fracture in the principal axes of stress, there is a ridge (line of the local maximum) of transmissivity in the circumferential direction, and the inclination angle of the ridge from the σ3-axis decreases with shear displacement, since shear dilation increases with both a decrease in normal stress and an increase in shear displacement. Furthermore, for the condition of stress given in this study, the transmissivity for macroscopic water flow in the direction of σ1is maximum for a fracture with a normal direction within the σ2–σ3plane, while that in the direction of σ2is maximum for a fracture with a normal direction within the σ1–σ3plane.