超深井厚煤层下山孤立煤体冲击机理研究

Study on Rock Burst Mechanism of Isolated Downhill Coal Body in Thick Coal Seam of Ultra Deep Well

为研究巷道切割形成孤立煤体冲击失稳机理,以古城煤矿32采区下山区域冲击地压事故为工程背景,通过现场调研、理论分析和数值模拟等方法,研究了巷道卸压后孤立煤体的应力演化规律,建立了巷道卸压后孤立煤体承载能力估算模型和支承压力分布简化模型,揭示了超深井下山孤立煤体整体失稳冲击机理:巷道卸压后孤立煤体弹性承载区应力集中,当该集中应力与采掘活动等其他应力叠加后的孤立煤体平均支承压力超过发生冲击临界值时,易诱发冲击。在此基础上提出了孤立煤体整体失稳冲击力学判据,事故案例及数值模拟计算验证了理论计算的正确性。在此基础上提出了降低孤立煤体平均支承压力和增强巷道围岩综合抗压强度的具体防治措施。

To study the mechanism of isolated coal body impact instability caused by roadway cutting,the impact rock burst accident in the 32 nd mining area of Gucheng Coal Mine was taken as the engineering background.Through the field investigation,numerical simulation and theoretical analysis,the isolated coal body after roadway pressure relief was studied.The stress evolution law is established.The model of the bearing capacity of the isolated coal body after the pressure relief of the roadway and the simplified model of the bearing pressure distribution are established.The mechanism of the overall instability of the isolated coal body in the ultra-deep well is revealed:the stress concentration is in the isolated coal body elastic load zone after the pressure relief of roadway,when the average supporting pressure of the isolated coal body after the concentrated stress and other stresses such as mining activities exceed the impact threshold,the impact is easily induced.Based on this,the criterion of the overall instability impact mechanics of the isolated coal body is proposed.The accident case and numerical simulation calculation verify the correctness of the theoretical calculation.On this basis,specific prevention measures for reducing the average supporting pressure of isolated coal and strengthening the comprehensive compressive strength of surrounding rock of roadway are proposed.