开挖卸荷扰动下的深部巷道支护及其效果评价

Deep Roadway Support and Its Effect Evaluation Under Excavation Unloading Disturbance

为了解决某金矿深部巷道存在的围岩灾变损伤严重、支护结构濒临失效的问题,开展了有关深部巷道开挖卸荷和采动影响耦合作用下的开挖损伤研究,并针对性地提出围岩变形控制方案。运用FLAC3D软件从应力集中—迁移演化、位移场和塑性区分布3个方面对该支护方案的支护效果进行深入探讨,并结合现场工程试验监测所获得的实时原位数据进行分析对比。研究结果表明:深部破碎化巷道在开挖扰动下塑性区扩展趋势明显,两帮肩部及侧墙底角处应力集中程度较高,底板所受破裂损伤压力最大,高应力向巷道深部迁移,最终巷道开挖影响区停留在半径的2~4倍。同时,验证了针对这种工程环境所施加的喷—锚—网联合支护替代传统的U型钢架、锚杆支护做补强支护这一围岩控制方案能够更好地发挥破碎化围岩的自承载能力,有效抵御巷道的变形破坏,具有良好的支护效果,能够为类似工程环境的矿山深部巷道围岩变形控制和支护设计提供合理化建议。

Roadway support work is very important to ensure the safety and sustainable development of enterprise production,reasonable support can not only ensure the stability of the roadway to the greatest extent,but also greatly save the cost of support.Especially in recent years,with the increase of mining depth,there is a high stress environment caused by excavation unloading and mining impact the deep roadway,which greatly increases the probability of safety hazards such as roof caving,gangstay or even collapse,so it is more necessary to optimize governance and time-effective support.In order to solve the serious catastrophic damage of the surrounding rock and the near failure of the supporting structure in the deep roadway of a gold mine,the excavation damage of deep roadway under the coupling effect of excavation and mining unloading was studied,and the deformation control scheme of surrounding rock was proposed.FLAC3Dwas used to conduct an in-depth discussion on the support effect of the supporting scheme from three aspects of stress concentration-migration evolution,displacement field and plastic zone distribution characteristics,and the real-time in-situ data obtained from field engineering experiment monitoring were analyzed and compared. The results show that under the disturbance of excavation in the deep fractured roadway,the plastic zone is obviously expanded,the stress concentration degree at both shoulders and the bottom corner of the side wall is high,the fracture damage pressure on the floor is the largest,and the high stress migrates to the deep part of the roadway.Finally,the influence of roadway excavation stays at about 2~4 times the radius.At the same time,according to the measured data,the stress of the surrounding rock of the roadway increases continuously during the unloading disturbance process of the roadway excavation,which indicates that the excavation disturbance in the adjacent stope will have a greater impact on the stability of the roadway.Before and after the support is applied,the average growth rate of the roadway surrounding rock stress decreases from 0.096 to 0.008.At this time,as the amount of ore continues to increase,the stress in the surrounding rock remains relatively stable. It is verified that the surrounding rock control scheme of shotcrete-anchor-net combined support instead of the traditional U-shaped steel frame and bolt support as reinforcement support for this engineering environment can better play the fragmented surrounding rock.The self-bearing capacity of the roadway effectively resists the deformation and damage of the roadway,and has a very good supporting effect. It can provide reasonable suggestions for the design of surrounding rock deformation and support for deep mine roadways with similar engineering environments.