Fractures provide preferential flow paths and establish the internal “plumbing” of the rock mass. Fracture surface roughness and the matedness between surfaces combine to delineate the fracture geometric aperture. New and published measurements show the inherent relation between roughness wavelength and amplitude. In fact, data cluster along a power trend consistent with fractal topography. Synthetic fractal surfaces created using this power law, kinematic constraints and contact mechanics are used to explore the evolution of aperture size distribution during normal loading and shear displacement. Results show that increments in normal stress shift the Gaussian aperture size distribution toward smaller apertures. On the other hand, shear displacements do not affect the aperture size distribution of unmated fractures; however, the aperture mean and standard deviation increase with shear displacement in initially mated fractures. We demonstrate that the cubic law is locally valid when fracture roughness follows the observed power law and allows for efficient numerical analyses of transmissivity. Simulations show that flow trajectories redistribute and flow channeling becomes more pronounced with increasing normal stress. Shear displacement induces early aperture anisotropy in initially mated fractures as contact points detach transversely to the shear direction; however, anisotropy decreases as fractures become unmated after large shear displacements. Radial transmissivity measurements obtained using a torsional ring shear device and data gathered from the literature support the development of robust phenomenological models that satisfy asymptotic trends. A power function accurately captures the evolution of transmissivity with normal stress, while a logistic function represents changes with shear displacement. A complementary hydro-chemo-mechanical study shows that positive feedback during reactive fluid flow heightens channeling.

裂缝提供了优先的流动路径并建立了岩体的内部“管道”。断裂表面粗糙度和表面之间的配合结合起来描绘了断裂几何孔径。新发布的测量结果显示了粗糙度波长和振幅之间的内在关系。事实上，数据沿着与分形地形一致的功率趋势聚集。使用此幂律创建的合成分形曲面、运动学约束和接触力学用于探索法向载荷和剪切位移期间孔径分布的演变。结果表明，法向应力的增加使高斯孔径尺寸分布向更小的孔径移动。另一方面，剪切位移不影响未配合裂缝的孔径分布；然而，孔径平均值和标准偏差随着初始配合裂缝中的剪切位移而增加。我们证明了当裂缝粗糙度遵循观察到的幂律并允许对透射率进行有效的数值分析时，三次定律是局部有效的。模拟表明，随着法向应力的增加，流动轨迹重新分布，流动通道变得更加明显。当接触点横向于剪切方向分离时，剪切位移在最初配合的裂缝中引起早期孔径各向异性；然而，当裂缝在大剪切位移后脱开时，各向异性会降低。使用扭环剪切装置获得的径向透射率测量值和从文献中收集的数据支持满足渐近趋势的稳健现象学模型的发展。幂函数准确地捕捉到透射率随正应力的演变，而逻辑函数表示随剪切位移的变化。一项补充性的水化学机械研究表明，反应性流体流动期间的正反馈增强了沟道效应。