Determination of Reasonable Advancing Speed of Fully Mechanized Top-coal Caving Face Based on Prevention and Control of Residual Coal Spontaneous Combustion

In order to study the effect laws of the advancing speed of the working face on the residual coal spontaneous combustion in the gob, study was carriied out in this paper on the the relationships of the advancing speed of the working face with the recovery rate, the distribution rule of the stress field and the porosity in the gob, the air leakage and the width of oxidation zone by means of the theoretical analysis, numerical simulation, similar simulation and regression analysis, the functional relations of the advancing speed of the working face with each factor and the reasonable determination method for the advancing speed of the working face were obtained. The analysis results showed that the lower limit and upper limit of the advancing speed of the working face existed for the prevention of residual coal spontaneous combustion, when there was a range of the reasonable advancing speed of the working face which was estimated with the lower and upper values, it had a larger changing space and the recovery rate was taken into consideration, the reasonable advancing speed of the working face for the effective prevention of residual coal spontaneous combustion can be obtained; when this range did not exist or was small, it indicated that the increase of the advancing speed of the working face can't prevent the residual coal spontaneous combustion, then the reasonable advancing speed of the working face should be determined by the recovery rate. If the advancing speed was slower and the relation curve with the width of the oxidation was more gentle, the increase of the advancing speed of the working face was more beneficial to the prevention of residual coal spontaneous combustion.