The mechanism and prevention of coal and gas outburst are investigated based on a rare coal and gas outburst accident in which the seam is shallow,soft,and lows gas.The results show that the accident caused by geological factors.The island area constituted by shallow and extremely thick roof,large area gob,and normal fault provides stress conditions for the accident.Vertical stress caused by the extremely thick roof's weight in the island area provides stress condition for coal seam damage and pregnant of the accident.Stress along the oblique direction provides ballistic performance for accident seam and throw coal.Such characteristics of coal seam as large gas desorption speed,low permeability,soft structure,thickness provides gas condition.According to the mechanism of the accident,the accident prevent and control methods is put forward which should prevent and control from the aspects of geological storage,high stress,gas.%以某矿浅埋松软煤层在瓦斯较低的条件下发生的瓦斯动力现象事故为背景,研究事故发生的机理及预防措施.研究表明:事故的发生由地质因素起主控作用,浅埋巨厚顶板、大面积采空区、正断层形成的"孤岛区"结构为事故的发生提供了应力条件;"孤岛区"内浅埋巨厚顶板沿煤层垂直方向产生的应力,为煤体破坏、瓦斯动力现象的孕育提供了条件,沿倾斜方向的应力,为事故煤层及煤体的抛出提供了弹性能;煤层瓦斯解吸速度快、低透气性、松软结构、厚度变化大的特征,为事故的发生提供了良好的瓦斯条件.根据事故发生的机理,提出了从地质构造赋存、高地应力、瓦斯三个方面进行灾害预防的方法.
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