Studying the frictional process, acoustic emission (AE) characteristics and permeability evolution of fractures under water injection is fundamental for proposing theories and methods to control the stability of geological structures. In this work, the shear-flow test was conducted on Longmaxi shale fractures with different specific roughness to analyze the frictional deformation and mechanical properties of shale fractures during the frictional slip process, and the influence of effective normal stress and surface morphology was investigated. AE monitoring technology was also utilized to reveal the AE evolution during the frictional slip process. Based on the AF/RA values, AE signals were subjected to cluster analysis using the Gaussian Mixture Model (GMM) to distinguish and quantify the crack types and proportions during frictional slip. Combining the development of cracks and considering the ratio of worn area, a theoretical analytical expression was established to reasonably describe the friction-damage evolution, classifying the friction-damage during the frictional slip process into tensile and shear damage, respectively. Meanwhile, the permeability evolution of Longmaxi shale fractures was also studied in detail. A theoretical model capable of describing and predicting the permeability evolution was proposed under the condition that the permeability evolution and damage process of Longmaxi shale fractures correspond to each other. Finally, the interaction between asperities on shale fractures with different surface morphologies during the frictional slip process was discussed, and the influence mechanism of surface morphology on permeability evolution was revealed.

中文翻译：

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特定粗糙度龙马溪页岩注水摩擦过程、声发射特征及渗透率演化


研究注水条件下裂缝的摩擦过程、声发射（AE）特征和渗透率演化是提出控制地质结构稳定性的理论和方法的基础。本文对不同粗糙度的龙马溪页岩裂缝进行剪切流试验，分析摩擦滑移过程中页岩裂缝的摩擦变形和力学特性，并研究有效正应力和表面形貌的影响。声发射监测技术也被用来揭示摩擦滑移过程中的声发射演变。基于 AF/RA 值，使用高斯混合模型 (GMM) 对 AE 信号进行聚类分析，以区分和量化摩擦滑动过程中的裂纹类型和比例。结合裂纹的发展情况并考虑磨损面积的比例，建立了合理描述摩擦损伤演化的理论解析表达式，将摩擦滑移过程中的摩擦损伤分别分为拉伸损伤和剪切损伤。同时，还对龙马溪组页岩裂缝渗透率演化进行了详细研究。在龙马溪组页岩裂缝渗透率演化与损伤过程相互对应的情况下，提出了能够描述和预测渗透率演化的理论模型。最后，讨论了不同表面形貌页岩裂缝在摩擦滑移过程中凹凸体之间的相互作用，揭示了表面形貌对渗透率演化的影响机制。