The shear resistance of multi-joint rock masses significantly affects the stability of underground engineering structures. In this work, using 3D printing technology, rock-like samples containing two joints with varying joint spacings and roughness values are prepared and subjected to direct shear tests under different normal stress conditions. The results demonstrate that the shear stress-shear displacement curve is influenced by the joint roughness coefficient (JRC) and normal stress. Peak shear stress increases with increasing JRC and normal stress but decreases with increasing joint spacing. Increases in JRC and normal stress increase the shear stress softening. The primary failure mode of the double-joint samples involves rock interlayer fracturing, the joint spacing has a smaller impact on shear failure mode than the JRC and normal stress. The shear failure behaviour and microcracking mechanism of a double-joint sample are revealed based on the developed cohesive zone model (CZM) method. Numerical tests revealed that the number of cracks in the double-joint model increases with increasing JRC and normal stress but decreases with increasing joint spacing. The model results in significantly more tensile cracks than shear cracks, tensile cracks are predominantly located in the rock interlayer of the double-joint model, whereas shear cracks are concentrated near the joint surfaces. This study explores the shear mechanical characteristics and microdamage behaviour of double-joint rock masses and offers foundational insights into the shear failure mechanisms of complex multi-joint rock masses.

中文翻译：

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标准 JRC 双节理岩体剪切行为的试验和数值研究


多节理岩体的抗剪强度显著影响地下工程结构的稳定性。在这项工作中，使用 3D 打印技术，制备了包含两个具有不同节理间距和粗糙度值的节理的岩石状样品，并在不同的法向应力条件下进行了直接剪切测试。结果表明，剪切应力-剪切位移曲线受节理粗糙度系数 （JRC） 和法向应力的影响。峰值剪切应力随 JRC 和法向应力的增加而增加，但随着节理间距的增加而减小。JRC 和法向应力的增加会增加剪切应力软化。双节理试样的主要破坏模式涉及岩石层间压裂，节理间距对剪切破坏模式的影响小于 JRC 和法向应力。基于开发的内聚区模型 （CZM） 方法揭示了双接头样品的剪切破坏行为和微裂纹机制。数值测试表明，双节理模型中的裂纹数量随着 JRC 和法向应力的增加而增加，但随着节理间距的增加而减少。该模型产生的拉伸裂纹明显多于剪切裂纹，拉伸裂纹主要位于双节理模型的岩石夹层中，而剪切裂纹集中在节理表面附近。本研究探讨了双节理岩体的剪切力学特性和微损伤行为，并为复杂多节理岩体的剪切破坏机制提供了基础见解。