放顶煤工作面立体自燃带动态变化特性研究

Research on dynamic change characteristics of three-dimensional spontaneous combustion zone in caving coal face

为探究采空区自燃带动态分布特征,采用理论分析、数值模拟与现场实测相结合的方法,研究空隙、裂隙结构及氧化速率改变对采空区漏风及氧气体积分数分布特征的影响,揭示综采放顶煤自燃带由采空区后部向工作面顶煤动态变化特性。结果表明:受采动应力及上覆岩层垮落滞后影响,顶煤裂隙及采空区空隙结构随暴露时间延长发生改变;支架后方中上部伞檐空场形成自由扩散漏风;随冒落煤岩体暴露时间增加,耗氧速率增大,顶煤裂隙结构发育,采空区垮落空间上移,中下部内部空隙结构下降,导致自燃带范围由采空区后部向综采支架顶煤范围扩展。

In order to explore dynamic distribution characteristics of spontaneous combustion zone in goaf, a combination of theoretical analysis, numerical simulation and field measurement were used to study effects of changes in voids, fracture structure and oxidation rate on features of air leakage and oxygen volume fraction distribution, and it was revealed that spontaneous combustion zone of fully mechanized top coal caving changed from the back of goaf to top coal in working face. The results show that the fracture of top coal and void structure of mined-out area change with extension of exposure time due to influence of mining stress and overburden caving lag. Free diffusion air leakage is formed in open field of upper and middle eaves behind the support, and as exposure time of caving coal and rock mass increase, oxygen consumption rate increases, top coal fracture structure develops, caving space in goaf moves up, and internal void structure in middle and lower part declines, leading to the expansion of spontaneous combustion zone from the back of goaf to top coal of fully mechanized mining support.