Numerical study of the geometrical and hydraulic characteristics of 3D self-affine rough fractures during shear
Numerical study of the geometrical and hydraulic characteristics of 3D self-affine rough fractures during shear
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剪切过程中三维自仿射粗糙裂缝几何和水力特性的数值研究
DOI：
10.1016/j.jngse.2017.05.018
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发表时间：
2017-09-01
影响因子：
--
通讯作者：
Jiang, Yujing
中科院分区：
文献类型：
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作者：
Huang, Na;Liu, Richeng;Jiang, Yujing
本研究提出一个预测模型，以估计在剪切过程中的三维自仿射粗糙裂缝的渗透率。采用改进的连续随机添加（SRA）算法生成一系列三维粗糙裂隙，对不同正应力下的剪切流试验进行了数值模拟，研究了裂隙开度和渗透率的演化规律。结果表明，裂隙剖面的节理粗糙度系数（JRC）服从高斯分布，JRC是岩石力学和岩石工程中广泛接受的表征裂隙表面粗糙度的参数。随着剪切位移的增加，孔径分布变得更加各向异性，并形成更复杂的流体流动通道。渗透率随正应力的增加而减小。在较小的正应力下，由于较大的正应力抑制了较大的膨胀，渗透率的变化更为显著。由于剪切诱导的显著流动通道，垂直于剪切方向的渗透率是平行于剪切方向的渗透率的约1.12-10.98倍。通过与以往工作中报道的结果进行比较，验证了所提出的渗透率预测函数的有效性。在实际应用中，当已知JRC、剪切位移和正应力等参数时，该模型可以很好地计算渗透率的一阶估计。(C)2017爱思唯尔B. V.保留所有权利。
This study presents a predictive model to estimate the permeability of 3D self-affine rough fractures during shear. Numerical simulations of shear-flow tests under different normal stresses were performed on a series of 3D rough fractures generated using the modified successive random additions (SRA) algorithm, and the evolutions of aperture and permeability were investigated. The results show that joint roughness coefficient (JRC) distribution of fracture profiles follows a Gauss function, where JRC is an extensively accepted parameter for characterizing fracture surface roughness in rock mechanics and rock engineering. As the shear displacement increases, aperture distribution becomes more anisotropic and more complex channels of fluid flow are formed. Permeability decreases with the increase in normal stress. For a smaller normal stress, the change of permeability is more significant because of the larger dilation inhibited by a larger normal stress. Due to the significant flow channels induced by shearing, the permeability in the direction perpendicular to the shear direction is approximately 1.12-10.98 times as large as that in the direction parallel to the shear direction. The validity of the proposed functions for permeability prediction is verified by comparisons with reported results in previous works. In practice, the permeability can be well calculated as a first-order estimation using the proposed model when the parameters such as JRC, shear displacement and normal stress are given. (C) 2017 Elsevier B.V. All rights reserved.