Mechanical excavation or blasting generates stress waves that rapidly dissipate in the surrounding high-geostress rock, causing microdynamic disturbances. These disturbances trigger microcracks within the damaged rock, even inducing engineering disasters. However, the fracture behaviors and mechanisms of rockmass subjected to excavation disturbances under three-dimensional geostress remains unclear. Therefore, this study proposed a true triaxial static–dynamic combined loading method to capture the entire process of tunnel excavation damage and the continuous fracturing induced by microdynamic disturbances. True triaxial static–dynamic combined tests and numerical simulations using PFC-GBM were employed systematically to analyze the influence of principal stresses , , and on the disturbances mechanical behaviors of the gabbro. The disturbance failure under true triaxial stress indicated a three-stage pattern of deformation: deceleration, constant velocity, and acceleration. With increased or decreasing and , the disturbance bearing capacity of the gabbro significantly decreased. Moreover, an increase in and corresponded to an increased proportion of intergranular shear cracks, whereas an increase in resulted in a notable increase in intragranular tensile cracks. Small-magnitude events tended to disperse during the deceleration and constant-velocity stages, whereas larger-magnitude events were concentrated during the acceleration stage. The AE parameter -value initially increased and then decreased during disturbance fracture process. The excavation disturbance of the tunnel intensified the depth of the damage zone and the energy released, thereby increasing the risk of a catastrophic deep fracture.

中文翻译：

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地下开挖扰动下岩石力学行为、细观裂纹机制及前兆的真三轴试验和DEM模拟


机械开挖或爆破产生的应力波会在周围的高地应力岩石中迅速消散，从而引起微动力扰动。这些扰动会引发受损岩石内的微裂纹，甚至引发工程灾难。然而，三维地应力作用下岩体在开挖扰动作用下的断裂行为和机制尚不清楚。因此，本研究提出了一种真正的三轴静动力联合加载方法来捕获隧道开挖损伤和微动力扰动引起的连续破裂的整个过程。系统地采用真三轴静动力联合试验和 PFC-GBM 数值模拟来分析主应力 、 、 和 对辉长岩扰动力学行为的影响。真实三轴应力下的扰动破坏表明变形的三阶段模式：减速、等速和加速。随着 和 的增大或减小，辉长岩的扰动承载能力显着下降。此外， 的增加对应于晶间剪切裂纹比例的增加，而 的增加导致晶内拉伸裂纹的显着增加。小震级事件在减速和等速阶段趋于分散，而较大震级事件在加速阶段趋于集中。扰动断裂过程中AE参数值先增大后减小。隧道的开挖扰动加剧了损伤区的深度和释放的能量，从而增加了发生灾难性深度断裂的风险。