Geometry of a single fracture has significant influence on the fluid flow in fractured rocks. However, quantification of geometry–flow relationship in a rock fracture is still far from being completed. The primary goal of this study was to identify a few key geometric parameters for quantifying its impact on fluid flow in a single rock fracture and then to evaluate its hydraulic conductivity. The concept of a threshold aperture is first introduced to estimate the effective area involved in the flow process in a single rock fracture. It is assumed that only those zones with greater apertures than a threshold value are involved in the flow process. The effect of variable aperture distributions on flow in a single rock fracture is quantified based on the cumulative distribution of individual apertures of sampling points. The surface roughness is decomposed into primary roughness (i.e. the large-scale waviness of the fracture morphology) and secondary roughness (i.e. the small-scale unevenness) with a wavelet analysis. The influence of surface roughness on the fluid flow in a single rock fracture is quantified with the normalized area of primary roughness and the standard deviation of secondary roughness. By combining the variable aperture distributions and the surface roughness on flow, an empirical equation to estimate the intrinsic hydraulic aperture and hydraulic conductivity of a single rock fracture is proposed. In addition, a series of high-precision hydraulic tests are conducted on 60 artificial tensile fractures to verify the proposed equation. The results show that the proposed equation predicts the intrinsic hydraulic aperture and hydraulic conductivity of a single rock fracture very well.

中文翻译：

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一种基于几何特征评价单岩裂隙导水率的创新方法

单个裂缝的几何形状对裂缝岩石中的流体流动有显着影响。然而，岩石裂缝中几何-流动关系的量化还远未完成。本研究的主要目标是确定几个关键几何参数，以量化其对单个岩石裂缝中流体流动的影响，然后评估其水力传导率。首先引入阈值孔径的概念来估计单个岩石裂缝中流动过程中涉及的有效面积。假设只有那些孔径大于阈值的区域参与流动过程。可变孔径分布对单个岩石裂缝中流动的影响是基于采样点各个孔径的累积分布来量化的。用小波分析将表面粗糙度分解为一次粗糙度（即断口形貌的大尺度波纹度）和二次粗糙度（即小尺度不平整度）。表面粗糙度对单个岩石裂缝中流体流动的影响用一次粗糙度的归一化面积和二次粗糙度的标准差来量化。通过结合可变孔径分布和流动的表面粗糙度，提出了估计单个岩石裂缝的固有水力孔径和水力传导率的经验方程。此外，对 60 条人工拉伸裂缝进行了一系列高精度水力试验，以验证所提出的方程。