突出和冲击地压中层裂现象的机理研究

针对突出和冲击地压中常出现的岩壁应力突然卸载的力学条件,建立简化的层裂发生及发展数学模型。利用动力学理论,分析了岩壁应力突然卸载时应力在岩体中的传播规律,得出了层裂破坏的原因,并通过数值模拟方法再现了层裂过程。结果表明,冲击地压中层裂现象产生的主要原因是由于地应力突然卸载而形成卸载波,该卸载波向深部传播过程中发生部分反射,反射波和入射波叠加使岩石受拉应力而破坏。煤与瓦斯突出中层裂现象的产生不仅受到卸载波反射叠加的影响,还受到瓦斯的影响,分别表现为高压游离瓦斯参与了煤中裂隙的扩展,以及伴随着层裂的间断性出现,瓦斯压力的间断性释放又会产生向深部传播的卸载波。

Mechanism Research on the Spall Fracture Phenomenon in Outburst and Coal Bump

Because of the frequent occurrence of suddenly unload of rock stress in outburst or coal bump,this mechanical condition was used to established a simplified spall fracture model.The stress propagation in rock mass after the suddenly unload of rock stress was analyzed based on kinetic theory,the cause of spall fracture was obtained,and the developing process of spall fracture was reproduced by numeric simulation.The result shows that the main cause of spall fracture in coal bump is the unloading wave which comes into being after the suddenly unload of rock stress,then part of the unloading wave is reflected during the propagation process into rock mass,the incoming wave and the reflecting wave interact to produce a tension region and thus lead to the tensile failure of rock.The cause of spall fracture in coal/gas outburst is affected not only by the interaction between incoming wave and reflection wave,but also by gas;gas influence manifest itself in two aspects,high pressure free gas is involved in the fracture propagation in coal,and the discontinuous releasing of gas pressure along with the discontinuous occurrence of spall fracture may induced inward propagating unloading wave again.