地表环境温度对煤田火系统影响的数值分析

Numerical Analysis on System Impact of Atmospheric Temperature to Coal-field Fires

煤田火灾持续燃烧的重要原因是存在沟通地表与地下的供氧裂隙,新疆煤田火区地表黄土覆盖稀薄、含砂量大形成了透气率较高的地层条件,加之四季温差大对地下煤田火系统具有一定的影响。建立了露头煤层自燃的数值模型,以新疆硫磺沟火区的四季温度为参数,分析了地下火区受四季温度影响下的内部压力场、温度场的演化过程。数值实验结果表明:地下火区的温度场分布范围随大气温度的降低而缩小,但影响范围随深度增加而减小;地下渗流气体的流速受外部压力和内部气体热膨胀效应的差值影响,一般随外部温度的下降而增大、升高而减小。

The reason for continuous combustion in coalfield is the existence of fractures which can provide oxygen between ground and underground. Xinjiang coalfield fires ground is covered by thin loess, and sediment content is high,the conditions with high-permeability layers is formed. The atmosphere temperature changes in a wide range in four reasons,so there has an impact on the system of coal-field fires. Numerical model was built ,the evolution process of inner pressure field and temperature field affected by the temperature change in four reasons. The result of numerical analysis shows that,the distribution range of temperature field of underground fire region will de- crease as atmosphere temperature drops,but the influence range of temperature field will decrease as atmosphere temperature rises. The velocity of underground gas flow,which is controlled by the D-value between atmospheric pressure and thermal expansion,will become large when temperature falls down, and become smaller when temperature rises.