Abstract Underground projects are typically performed in nonpersistent jointed rock masses. Excavation of tunnels or chambers causes crack initiation, propagation and coalescence, resulting in the instability and destruction of surrounding rocks. The failure behaviour of rocks is complicated owing to the interaction between holes and joints. Therefore, understanding the failure characteristics of holes in jointed rock masses is essential. In this paper, the mechanical characteristics of a jointed rock mass with double circular holes under uniaxial loading was investigated using the discrete element method. The effects of different joint parameters on the strength and failure behaviour of the jointed rock mass with double circular holes were studied. The results show that the existence of joints degrades the mechanical behaviour of the rock mass. Specifically, the peak strength and elastic modulus of the specimens show a “U” shape change with the joint dip angle and reach the minimum value when the angle is 30°. With an increase in joint spacing, the peak strength and elastic modulus increase gradually. An investigation of the crack coalescence process and displacement field of the specimens reveal the crack propagation mechanism based on the interaction between holes and joints under uniaxial loading. Five types of crack coalescence among the holes and adjacent joints were summarized. Four typical failure modes were observed: tensile failure across joints, block rotation failure around holes, shear failure through joint planes and tensile–shear mixed failure through holes.

中文翻译：

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单轴压缩双圆孔节理岩体的强度与破坏特性：离散元方法建模的启示

摘要 地下工程通常在非持久的节理岩体中进行。隧道或室的开挖引起裂缝的萌生、扩展和聚结，导致围岩的失稳和破坏。由于孔洞和节理之间的相互作用，岩石的破坏行为是复杂的。因此，了解节理岩体中孔洞的破坏特征至关重要。本文采用离散元方法研究了单轴加载下双圆孔节理岩体的力学特性。研究了不同节理参数对双圆孔节理岩体强度和破坏行为的影响。结果表明节理的存在降低了岩体的力学行为。具体而言，试样的峰值强度和弹性模量随着接头倾角呈“U”形变化，在倾角为30°时达到最小值。随着接头间距的增加，峰值强度和弹性模量逐渐增加。对试样的裂纹合并过程和位移场的研究揭示了基于单轴加载下孔和接头之间相互作用的裂纹扩展机制。总结了孔和相邻接缝之间的五种裂纹合并。观察到四种典型的破坏模式：跨接头的拉伸破坏、围绕孔的块旋转破坏、通过接头平面的剪切破坏和通过孔的拉伸-剪切混合破坏。试样的峰值强度和弹性模量随接头倾角呈“U”形变化，倾角为30°时达到最小值。随着接头间距的增加，峰值强度和弹性模量逐渐增加。对试样的裂纹合并过程和位移场的研究揭示了基于单轴加载下孔和接头之间相互作用的裂纹扩展机制。总结了孔和相邻接缝之间的五种裂纹合并。观察到四种典型的破坏模式：跨接头的拉伸破坏、围绕孔的块旋转破坏、通过接头平面的剪切破坏和通过孔的拉伸-剪切混合破坏。试样的峰值强度和弹性模量随接头倾角呈“U”形变化，倾角为30°时达到最小值。随着接头间距的增加，峰值强度和弹性模量逐渐增加。对试样的裂纹合并过程和位移场的研究揭示了基于单轴加载下孔和接头之间相互作用的裂纹扩展机制。总结了孔和相邻接缝之间的五种裂纹合并。观察到四种典型的破坏模式：跨接头的拉伸破坏、围绕孔的块旋转破坏、通过接头平面的剪切破坏和通过孔的拉伸-剪切混合破坏。峰值强度和弹性模量逐渐增加。对试样的裂纹合并过程和位移场的研究揭示了基于单轴加载下孔和接头之间相互作用的裂纹扩展机制。总结了孔和相邻接缝之间的五种裂纹合并。观察到四种典型的破坏模式：跨接头的拉伸破坏、围绕孔的块旋转破坏、通过接头平面的剪切破坏和通过孔的拉伸-剪切混合破坏。峰值强度和弹性模量逐渐增加。对试样的裂纹合并过程和位移场的研究揭示了基于单轴加载下孔和接头之间相互作用的裂纹扩展机制。总结了孔和相邻接缝之间的五种裂纹合并。观察到四种典型的破坏模式：跨接头的拉伸破坏、围绕孔的块旋转破坏、通过接头平面的剪切破坏和通过孔的拉伸-剪切混合破坏。