Persistency, as a key geometric parameter of joints, significantly affects shear strength parameters of jointed rock mass. A good understanding of how persistency affects shear behavior of joint is therefore crucial for better evaluation of stability of rock slope. To investigate the failure and micro-cracking behavior of non-persistent rock joint under direct shear, a novel Voronoi generation algorithm is first used to establish an improved grain-based model (GBM) of granite which considers the shape of feldspar. The calibrated model is then used to simulate the direct shear test of numerical models possessing different joint persistency under various normal stresses. The results reveal that the developed micro-cracks generally increase rapidly when the shear strain reaches to a value approximately 50 % of the peak shear strain and the grain boundary tensile micro-crack is dominant among these initiated micro-cracks. Micro-cracks generally initiate at the ends of rock bridge, and then gradually propagate to the central of rock bridge, forming en-echelon fractures. The failure mode of numerical model is closely related to the generated en-echelon fractures. An increase in both joint persistency and normal stress can lead to a shear failure. The finding in this study provides an important basis for understanding the mechanical behavior and failure mechanism of jointed rock mass.

中文翻译：

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直剪作用下非持续性岩石节理破坏及微裂纹行为的数值模拟


持久性作为节理的关键几何参数，对节理岩体的抗剪强度参数有显著影响。因此，充分了解持久性如何影响节理的剪切行为对于更好地评估岩石边坡的稳定性至关重要。为了研究非持久性岩石节理在直接剪切作用下的破坏和微裂纹行为，首先使用一种新的 Voronoi 生成算法建立了一种考虑长石形状的改进花岗岩基于颗粒的模型 （GBM）。然后使用校准模型模拟在各种法向应力下具有不同关节持久性的数值模型的直接剪切试验。结果表明：当剪切应变达到峰值剪切应变的 50 % 左右时，形成的微裂纹通常会迅速增加，并且晶界拉伸微裂纹在这些引发的微裂纹中占主导地位。微裂纹一般始于岩桥末端，然后逐渐向岩桥中心蔓延，形成梯形裂缝。数值模型的破坏模式与生成的梯次裂缝密切相关。关节持久性和法向应力的增加都可能导致剪切破坏。本研究结果为理解节理岩体的力学行为和破坏机理提供了重要依据。