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高瓦斯煤层冲击地压发生条件与影响因素

CONDITION AND INFLUENCE FACTOR OF ROCK BURST IN HIGH GASSY COAL SEAM

  • 摘要: 针对高瓦斯煤层冲击地压问题,用解析方法得到冲击地压发生条件,分析了主要影响因素对满足冲击地压发生条件的临界塑性区半径和临界应力的影响规律。结合五龙矿开采实际情况对影响高瓦斯煤层冲击地压的煤的模量比、煤层瓦斯孔隙压力、支护应力和内摩擦角4个因素做了对比分析。研究发现:高瓦斯煤层在巷道掘进面附近由于存在开挖面空间效应,掘进面前方尚未开挖的煤体对巷道变形起到了限制作用,减少了冲击地压的发生,随着掘进面向前推进,后方一定距离范围内的巷道支护应力增大。随着瓦斯解吸渗流的进行,巷道壁处孔隙压力降低,巷道冲击地压危险性明显提高,此时提高支护应力,冲击危险性有所降低。高瓦斯煤层巷道发生冲击地压的临界塑性区半径和临界应力随模量比、瓦斯孔隙压力的增大而快速减小,随支护应力的增大而增大,临界塑性区半径随内摩擦角的增大而增大,临界应力与内摩擦角不是单调函数关系,存在一个极小值点,当内摩擦角小于此极小值时,临界应力随内摩擦角增大而减小;当内摩擦角大于此极小值时,临界应力随内摩擦角增大而增大。

     

    Abstract: Aiming at the problem of rock burst in high gassy coal seam, the occurrence conditions of rock burst are obtained by analytical analysis, the influence rule of main factors on the radius and the critical stress of the critical plastic zone are analyzed. In connection with Wulong mining practice, the effects of the coal modulus ratio, gas pore pressure, support stress, and internal friction angle on rock burst of in high gassy coal seam are analyzed in comparison. The results show that, non excavated solid coal plays a limiting role in the deformation of the roadway because of the spatial effect with excavation face nearby roadway heading face about high gassy coal seam. It reduces the danger of rock burst, the support stress of the roadway is increased in a certain distance from the rear along with the excavating face ahead. At the same time, along with the gas desorption seepage, the pore pressure of the tunnel wall is decreased, and the risk of rock and the critical stress of the high gassy coal seam tunnel decrease rapidly with the increase of the modulus ratio λ=E and the pore pressure, and they increase with the increase of the support stress, the radius of the critical plastic zone increases with the increase of the internal friction angle, the relationship between the critical stress and the internal friction angle is not monotone, there exists a minimum value, when the internal friction angle is less than the minimum value, the critical stress decreases with the increase of the internal friction angle; when the internal friction angle is larger, the results are opposite.

     

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