Microcirculation of air leakage of gob-side coal pillar in fully-mechanized face

Microcirculation of air leakage among the gob behind the working face, the gob-side coal pillar and the adjacent gob is investigated theoretically by nonlinear seepage equation. The 2D model is built containing two gobs with heterogeneous porosity distribution and one gob-side coal pillar. Velocity field and streamline distribution of the microcirculation are simulated by the commercial code Fluent. Causes of the microcirculation are also discussed. The results show that fresh air flows into the gob behind the working face, and penetrates into the adjacent gob through the gob-side coal pillar. Microcirculation of air leakage increases air volume that flows into the gob and promotes the spontaneous combustion of residual coal. Gob breathe is also initiated by the oxidation process in which the consumption and supplement of oxygen alternates and thus results in the fluctuation of concentration of CO and O-2.