Effects of fracture surface roughness and shear displacement on geometrical and hydraulic properties of three-dimensional crossed rock fracture models
Effects of fracture surface roughness and shear displacement on geometrical and hydraulic properties of three-dimensional crossed rock fracture models
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DOI：
10.1016/j.advwatres.2018.01.005
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发表时间：
2018-03
影响因子：
4.7
通讯作者：
N. Huang;Ri-cheng Liu;Yujing Jiang;Bo Li;Liyuan Yu
中科院分区：
文献类型：
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作者：
N. Huang;Ri-cheng Liu;Yujing Jiang;Bo Li;Liyuan Yu
虽然通过裂缝介质的剪切流动行为已经在单裂缝尺度上进行了研究，但三维交叉裂缝模型的水力响应的剪切效应的数值分析。分析是基于一系列的交叉裂缝模型，其中考虑了裂缝表面粗糙度和剪切位移的影响。采用改进的连续随机添加（SRA）算法生成粗糙断裂面。在一个裂缝上施加剪切位移，同时另一个裂缝沿剪切裂缝的上、下表面沿着移动。模拟结果揭示了剪切过程中优先流路的发展和变化，并伴随着出口边界两个流面之间流量比的变化。剪切过程中的平均接触面积约占断裂面的5-27%，但实际计算的流动面积约为断裂面的38-55%，远小于非接触面积。等效渗透率随剪切位移的增大而增大或减小，其大小取决于裂缝交汇处的孔径分布。当剪切位移连续增加到20 mm时，等效渗透率先急剧增加，然后以较低的梯度继续增加。粗糙裂隙模型的等效渗透率约为平行板模型等效渗透率的26-80%，垂直于剪切方向的等效渗透率约为平行于剪切方向的1.31-3.67倍。这些结果可以为剪切作用下流体在交叉裂缝模型中的流动提供基本的认识。
While shear-flow behavior through fractured media has been so far studied at single fracture scale, a numerical analysis of the shear effect on the hydraulic response of 3D crossed fracture model is presented. The analysis was based on a series of crossed fracture models, in which the effects of fracture surface roughness and shear displacement were considered. The rough fracture surfaces were generated using the modified successive random additions (SRA) algorithm. The shear displacement was applied on one fracture, and at the same time another fracture shifted along with the upper and lower surfaces of the sheared fracture. The simulation results reveal the development and variation of preferential flow paths through the model during the shear, accompanied by the change of the flow rate ratios between two flow planes at the outlet boundary. The average contact area accounts for approximately 5–27% of the fracture planes during shear, but the actual calculated flow area is about 38–55% of the fracture planes, which is much smaller than the noncontact area. The equivalent permeability will either increase or decrease as shear displacement increases from 0 to 4 mm, depending on the aperture distribution of intersection part between two fractures. When the shear displacement continuously increases by up to 20 mm, the equivalent permeability increases sharply first, and then keeps increasing with a lower gradient. The equivalent permeability of rough fractured model is about 26–80% of that calculated from the parallel plate model, and the equivalent permeability in the direction perpendicular to shear direction is approximately 1.31–3.67 times larger than that in the direction parallel to shear direction. These results can provide a fundamental understanding of fluid flow through crossed fracture model under shear.