实体煤掘进加卸载路径下的冲击机理及防控研究

Study on mechanism and prevention of rock burst under loading and unloading path in solid coal driving

实体煤掘进冲击矿压受覆岩运动影响较小是其典型特点,其冲击机理缺乏系统研究。本文从实体煤掘进围岩力学行为入手,展开其冲击机理及防控研究。首先,运用数值模拟方法得到煤巷掘进围岩应力路径具有"竖向加载-倾向卸载-走向固定"的三轴加卸载特征;然后展开三轴加卸载路径下的煤样力学和冲击特征试验;最后用试验结果指导实体煤掘进冲击防控设计。试验揭示了煤样峰值点的加卸载侧应力不仅受初始加载侧应力和初始卸载侧应力影响,而且与卸载速率和加载速率比值(简称"卸加比")呈指数型降低,但是受初始固定侧应力影响较小。发现实验室煤样需要满足高应变速率和高应力2个条件才能形成冲击,非冲击煤样和冲击煤样分别呈现层裂式和爆裂式破坏特征,前者对应的声发射能量值比后者小2个数量级。根据加卸载下煤样破裂特征及冲击形成条件,制定相应的实体煤掘进冲击防控设计方案。现场实践表明,所设计的实体煤巷道掘进冲击防控方案有效降低了大能级矿震和冲击矿压的发生概率。

Rock burst during solid coal roadway excavation is always slightly affected by the movement of overburden rock.However,few systematic research has been conducted on that rock burst mechanism.In this study,the mechanism and prevention of rock burst during solid coal roadway excavation were studied from perspective of mechanical behavior of surrounding rock.Firstly,the triaxial stress path characteristics of surrounding rock during roadway excavation were obtained through using numerical simulation,which are"vertical loading-inclined unloading-strike fixed".Then mechanical and burst behavior tests of coal samples under triaxial loading and unloading path were conducted.Finally,above results were used to guide the design of rock burst prevention during solid coal driving.Results show that the peak stress of coal samples are not only affected by initial loading and unloading lateral stress,but also has a negative exponential relationship with the ratio of unloading rate and loading rate.However,it is less affected by the initial fixed side stress.Rock burst is commonly induced by high strain rate and high stress in the experiments.The non-burst coal samples and burst coal samples could be characterized by exfoliation and decrepitation,respectively.Meanwhile,the acoustic emission energy value corresponding to the former is two orders of magnitude smaller than the latter.According to fracture characteristics of coal samples under loading and unloading and the forming process of rock burst,design scheme of rock burst control for solid coal driving are provided.Engineering application show that the rock burst prevention design for solid coal roadway driving could effectively reduce the probability of strong tremors and rock bursts.