深部隧道围岩分区破裂颗粒流模拟研究

深部岩体处于"三高"环境下,表现出不同于浅埋岩体的性质,其变形破裂规律更为复杂(分区破裂、片帮、塑性流动、岩爆等),为了准确描绘深部隧道围岩变形破裂规律,采用PFC从微观角度研究深部岩体的宏观响应。研究发现:随着隧道埋深增加,压力增大,由浅部围岩表面塑性破坏变为深部围岩破裂扩展,破裂区域呈交替分区破裂向深部发展,破裂区的间距与岩性和埋深有关;从横断面看,拱腰先出现破裂,然后拱脚出现破裂,最后贯通形成破裂区;若围岩表面施加外力,破裂区域减小,分区向深部移动,因此预应力锚杆有效地改善了围岩承载特性;研究结果与模型试验吻合,符合深部岩体卸荷作用下的变形破坏规律。结论可为深部岩体工程设计施工提供参考。

Particle Flow Simulation of Zonal Disintegration inDeep Tunnel Surrounding Rock

With the development and utilization of deep resources, there is an increasing number of problems associated with deep rock masses. In environments characterized by high stress, high water pressure, and high temperature with more complex crack deformations (including zone cracks, rock blasts, splits on side walls, and plastic fluids), deep rock masses exhibit different corresponding characteristics than those of shallow rock masses. In this study, to precisely describe the deformation laws of deep rock masses, we used PFC software to examine the macro-responses of deep rock masses by micro-scale stimulation. The results show that with increased depth, temperature, and pressure, the plastic damage in shallow surrounding rock becomes crack damage in deep surrounding rock, with crack zones and alternating zonal disintegration with depth. The spacing of the crack zone is related to the rock mass properties and depth. In the cross section of tunnels, the first crack zone appears in the haunch of the arch and then at the arch springing line, eventually becoming an entire crack zone. If pressure is exerted on the surface of the surrounding rock, the crack zone will decrease and move into the deep area. As such, a pre-stressed anchor can effectively improve the bearing characteristics of surrounding rock and reduce the number of cracks. These results agree with model-test data and also reflect the deformation law of deep rock masses. These conclusions provide a valuable reference for the design and construction of deep underground engineering projects.