深部巷帮煤体失稳机制及能量释放特征

Study on coal rib burst mechanism and its energy release characteristic in deep roadways

冲击地压灾害已成为国内外煤矿井下开采的重大安全隐患。利用真三轴电液伺服加载试验系统,研究了巷帮煤岩组合体三向应力加载、煤体三向和两向应力加载下的应力-应变规律、破坏特征、声发射活动规律,建立了巷帮深、浅部煤体的强度准则关系,分析了深部巷帮煤体的能量释放特征,揭示了深部巷帮煤体失稳诱冲机理。结果表明:不同应力类型的煤体试样受应力环境及结构差异的影响,巷帮浅部煤体试样和高σ_(2)围压条件下的巷帮煤岩组合体试样在峰值应力后均产生应力快速跌落现象,脆性破坏与冲击性较强;在破坏机制上,巷帮浅部煤体试样主要受张拉−剪切耦合机制控制;巷帮深部煤体试样主要受剪切机制控制;巷帮煤岩组合体试样靠近约束面、自由面区域分别受剪切、张拉−剪切耦合机制控制。同围压条件下巷帮浅部煤体更容易破坏,进而基于巷道煤帮冲击能量释放的来源,建立了深部巷帮煤体失稳模型,揭示了深部巷帮煤体失稳机制。

Rock burst disaster has become a major safety problem in underground coal mining worldwide.Using the true triaxial electro-hydraulic servo loading test system,the stress-strain law,failure characteristics and acoustic emission activity law of coal-rock combination,deep coal body and shallow coal body with three different stress types are studied.The strength criterion relationship of deep and shallow coal bodies is established,the energy release characteristics of deep coal body are analyzed,and the instability mechanism of deep coal body is revealed.The results show that the coal samples with different stress types are affected by the stress environment and structural differences.The shallow coal samples of the roadway rib and the coal-rock combination samples of the roadway rib under high σ_(2) confining pressure all produce rapid stress drop after the peak stress,and the brittle failure and impact are strong.In the failure mechanism,the shallow coal sample of the roadway is mainly controlled by the tensile-shear coupling mechanism.The deep coal sample of the roadway is mainly controlled by the shear mechanism.The area near the constraint surface and the free surface of the coalrock combination sample is controlled by the shear and tension-shear coupling mechanism respectively.Under the condition of same confining pressure,the shallow coal body of the roadway is more likely to be destroyed.Based on the source of the impact energy release of the roadway coal rib,the instability model of the coal body in the deep roadway is established,and the instability mechanism of the coal body in the deep roadway is revealed.