For the tectonic coal ， the properties of higher porosity and lower permeability make it capable of keeping higher gas pressure ； both of the “ isolating action ” and “ gas - cushion action ” cut down the resistance against outburst ； the specifity of high - defomed - extent makes desorption ， escape and flowing quickly become possible ； the existing of weak - seam or “ thoroughfare - seam ” create suitable conditions for the initial erupting and continued developing of coal and gas outburst . on the whole ， it is the synhesis action of all factors ， which leads to outbursts . the existing of tectonic coal with certain thickess is the essential condition of coal and gas outbursts ， but not the sufficient condition 高空隙率、低透气性使构造煤能够保持较高的瓦斯压力；破碎性、 “隔离”作用及“气垫”作用，使构造煤抵御外力作用的能力大大降低；构造煤变形幅度大的特性，为瓦斯的迅速解吸、放散和快速流动创造了条件；构造煤薄弱分层或“通道层”的存在，则为煤与瓦斯突出的初始激发和持续发展奠定了基础；上述因素的共同作用，影响和制约了煤与瓦斯突出的强度和分布.尽管如此，一定厚度的构造煤的存在只是发生煤与瓦斯突出的必要条件和有利条件，而非充分条件
