“三软”矿区采掘工作面煤与瓦斯延期突出机理

Mechanism of delayed coal and gas outbust on working face in “three soft” mining areas

针对我国"三软"矿区含瓦斯软煤严重的蠕变失稳问题,串联一个非线性黏塑性体与四元件线性黏弹性伯格体模型,建立含瓦斯软煤非线性黏弹塑性流变模型,并据此推导了煤壁蠕变失稳时间公式.针对采区工作面前方的矿压时空演化特征,建立了地应力和瓦斯压力随时间变化的函数M(t);通过煤与瓦斯突出判断条件,探讨了卸压区的形成对煤与瓦斯延期突出的影响.结果表明:"三软"矿区延期突出的滞后时间为第1阶段卸压带形成时间与第2阶段应力集中带软煤蠕变失稳时间之和.

In order to study the serious creep buckling problem of gas-containing soft coal in ＂three soft＂ area in China, a new nonlinear viscoelasto-plastic rheological model of gas-contai- ning coal was established by connecting a nonlinear viscoplastic body and four-component linear viscoelastic Burgers model, and then creep buckling time formula of coal wall was derived. Function M（t） was established based on space-time evolution characteristics of mining pressure before coal extraction face, which can indicate the change of ground stress and gas pressure o- ver time, and then the influence of distressed zone formation on delay outburst of coal and gas was discussed through the judgment condition of coal and gas outburst. The results show that the total time of delay outburst in ＂three soft＂ coal mine is the sum of the formation time of distressed zone in the first stage and creep buckling time of soft coal in stress concentration zone in the second stage.