瓦斯压力作用下煤岩裂纹扩展机理研究

Study on the Mechanism of Fracture Propagation in Coal-Rock under Gas Pressure

瓦斯压力作用下煤岩裂纹扩展是煤与瓦斯突出的必经环节。利用断裂力学方法对裂纹扩展机理进行了研究,首先给出了裂纹内作用有瓦斯压力时裂纹表面的正应力和剪应力表达式,然后分拉剪破坏和压剪破坏两种情况分析了裂纹扩展方向、临界瓦斯压力与侧压系数之间的关系。研究表明,对于拉剪裂纹,裂纹方向与最大主应力方向一致时最易扩展;对于压剪裂纹,压剪参数与摩擦系数的差值决定裂纹的扩展方向。

The fracture propagation in coal - rock under gas pressure is a necessary process for coal and gas outburst. The mechanism of fracture propagation in coal - rock is studied by using fracture mechanics. The expressions of the normal stress and shear stress on the surface of fracture under gas pressure are given first. Then the relationship among the direction of fracture propagation, critical gas pressure and side pressure coefficient is analyzed according to the two situations of tension - shear failure and compression - shear failure. The studies show that for tension - shear fracture,the fracture will be easy to propagate while the fracture has the same direction as maximum principal stress, and for compression - shear fracture, the propagation direction depends on the difference of compression - shear parameter and friction coefficients.