The evolution of fracture geometries caused by asperity damage and gouge formation during the shear significantly affect fluid flow in rock fractures. In this research, a cylindrical sandstone sample was fractured by using the Brazilian splitting test. Fluid flow tests and 3D scanning methods were performed on the fractured sample when it was sheared, to examine how shear-induced alteration of fracture geometries affected the permeability. A simplified modeling algorithm was proposed to quantitatively characterize the asperity degradation and gouge accumulation within the fracture during shear, based on which a series of fracture geometries models at different shear stages were established to conduct the N–S (Navier-Stokes) flow simulations, allowing for an analysis of the link between the fracture geometries evolution and the change in flow behavior during shear. Test results show that shear dilation increase the permeability at the early shearing stages but then was offset by the gouge formation at the residual shear stages, leading to the reduce of fracture permeability. The simulated distribution of asperity degradation and gouge distribution, as well as the normalized permeability change in the sheared fracture correlated well with the experimental measurements. Simulation results show that the fracture permeability is affected not only by the fracture aperture but also by the distribution, location and size of contacts evolving during shear. The channeling flow become more dominant as the shear displacement increases; this is largely controlled by the location of contacts that span almost the entire width of the fracture and has the tendency to block the flow paths. The fluid flow transforms from the dispersion at the early shearing stage to the apparent channeling flow along the narrow side of the fracture in the later shearing stages.

剪切过程中由凹凸不平损坏和凿孔形成引起的裂缝几何形状的演变显着影响岩石裂缝中的流体流动。在这项研究中，使用巴西劈裂试验将圆柱形砂岩样品压裂。剪切样品时，对断裂的样品进行了流体流动测试和3D扫描方法，以检查剪切引起的断裂几何形状的变化如何影响渗透率。提出了一种简化的建模算法来定量表征剪切过程中裂缝内的凹凸不平降解和凿痕积聚，在此基础上，建立了一系列在不同剪切阶段的裂缝几何模型，以进行N–S（Navier-Stokes）流动模拟，分析裂缝几何形状演变与剪切过程中流动行为之间的联系。试验结果表明，剪切膨胀在早期剪切阶段增加了渗透率，但在残余剪切阶段被切屑形成所抵消，导致裂缝渗透率降低。粗糙变形和断层分布的模拟分布以及剪切裂缝中的归一化渗透率变化与实验测量值具有很好的相关性。仿真结果表明，裂缝的渗透率不仅受岩心的影响。断裂孔的大小，还取决于剪切过程中不断变化的接触的分布，位置和大小。随着剪切位移的增加，窜流变得更加占优势。这主要是由接触点的位置控制的，这些接触点几乎跨越了裂缝的整个宽度，并且有阻塞流动路径的趋势。流体流动从早期剪切阶段的分散体转变为沿后期剪切阶段的裂缝狭窄侧的表观窜流。