煤矿冲击地压与冒顶复合灾害研究

Study on compound disaster of rock burst and roof falling in coal mines

随着煤矿向深部发展,矿井动力灾害既表现出冲击地压的部分特征,又表现出冒顶的部分特征。2种典型的灾害打破以往冒顶与冲击地压的发生具有一种互为逆向性的认知规律,在深部高应力煤巷,特别是留顶煤巷道中出现了相互诱导、复合发生的新灾害类型。在总结山东、山西和新疆矿区典型巷道冲击致顶板(顶煤)动力灾害特征的基础上,提出了深部巷道冲击地压与冒顶复合灾害的概念、机理与分类,指出复合灾害机理关键点在于揭示巷道整体系统和破碎区子系统的稳定原理及其2者间的相互影响。建立了巷道发生复合灾害的力学模型,根据扰动响应失稳判据,提出并得到了巷道发生复合灾害的临界应力Pcr、临界软化区半径ρ_(cr)和最大容许采扰应力增量σ_(max),厘清了灾害发生的主控因素,分析了煤岩冲击倾向指数K、支护强度ps、巷道半径ρ_(0)、煤岩强度σ_(c)等对灾害发生的影响规律,同时阐明了围岩塑性软化、破碎深度随地应力增加的发育规律。研究结果表明,破碎发育巷道的动力失稳主体为弹性区、软化区与破碎区构成的不稳定系统,垮落主体为破碎区;稳定的破碎区提升了巷道冲击启动临界值,使其启动难度增大,但破碎区的发育又易引起顶煤垮落;巷道稳定支护是解决复合灾害的关键,科学合理支护既能有效调控围岩破碎防冒,又能提升冲击启动临界值。通过理论研究,揭示了巷道冲击地压与冒顶复合灾害的发生机理,阐明了巷道软化与破碎区及其稳控支护对深部破碎发育巷道动力灾害防治的重要性。

With the development of coal mine to the deeper zone,the dynamic disaster of coal mines not only shows some characteristics of rock burst,but also shows some characteristics of roof falling.The two typical disasters break the previous cognitive law that the occurrence of roof fall and rock burst is mutually converse.These two type of disasters are mutually induced and compounded in deep coal roadway with high stress,especially coal roadway with thick top coal.On the basis of summarizing the characteristics of roof(top coal)accidents caused by rock burst of typical roadways in Shandong,Shanxi and Xinjiang mining areas,the concept,mechanism and classification of the compound disaster of rock burst and roof fall in deep roadway were proposed.It is pointed out that the key point of compound disaster mechanism is to reveal the stability principle of the whole roadway system,the subsystem of the fracture area and their interaction.In this paper,the mechanical model of compound disaster in roadway was established.According to the criterion of disturbance response instability,the critical load,the radius of critical softening zone and maximum allowable disturbance stress increment were obtained,the main control factors of the disaster were clarified and the influence of rock burst tendency index,support strength,roadway radius and uniaxial compressive strength on the occurrence of the disaster was analyzed.In addition,the development law of the surrounding rock softening and fracture depth along the increase of the ground stress was clarified.The results show that the main body of dynamic instability of roadway is an unstable system composed of elastic zone,softening zone and fracture zone,and the main body of falling is fracture area.The stable fracture area increases the critical value of rock burst start-up,which makes it more difficult to start,but the development of fracture area is easy to cause roof fall.Roadway stability support is the key to solve the compound disaster.Scientific and reasonable support can not only effectively control the surrounding rock fracture and roof falling-resistant,but also improve the critical value of rock burst start-up.The occurrence mechanism of the compound disaster of rock burst and roof fall is revealed with theoretical study,and the significance of the softening and fracture area and its stability control for the prevention and control of the dynamic disaster in the deep roadway is clarified.