Study On The Mechanism Of Concealed Fire Of Coal Pillar In Mining Roadway

The coal seam of No.9th coal seam in the south one mining area of Kailuan Dong Huan Tuo coal mine belongs to spontaneous combustion,and the problems such as the deformation and failure of pillar and the surface spontaneous combustion of coal pillar seriously affect the safety production of coal mine during the excavation of the 2394 working face.Therefore,aiming at the characteristics of Dong Huan Tuo coal mine,this paper probes into the causes of the hidden fire of the coal pillar in the mining roadway,which is of great significance to prevent and control the coal pillar fire and ensure the safety production of the mine.In view of the actual situation of the coal mine site in Dong Huan Tuo,the development process of the coal pillar fissure in the upper 9 coal seam roadway in 2394 working face in the 12-1 coal seam of the mining area and the deep study on the spontaneous combustion of the coal pillar were carried out by theoretical analysis,numerical simulation and similar material simulation experiment.By establishing the numerical simulation model of the coal pillar in the mining roadway of the 2394 working face of the Dong Huan Tuo,this paper analyzes the variation characteristics of the stress field and the displacement field of the coal pillar in the mining roadway of the upper oblique 2394 working face in the 2322 working face.At the same time,the spatial-temporal relationship of two coal seam is analyzed and calculated to reach the range of caving zone and fissure zone height and downhill boundary in the 2322 working face,the study shows that in the mining process of the lower coal seam 2322 working face,the coal pillar of 2394 working face will be formed obviously.Lead to fracture development and deformation damage of coal pillar in upper seam.The effect of the coal pillar in the mining roadway in the 12-1 coal seam 2322 face of the Dong Huan Tuo coal mine is analyzed by using similar material simulation experiment.The results show that the subsidence zone and the fractured zone have influence on the coal pillar at the top of the roof strata caused by the mining action.The stress state of coal pillar is changed,which leads to the development of coal pillar fissure and the trend of internal expansion.The simulation and FLAC3 D numerical simulation of similar materials and the actual situation in the field show that the coal pillar is deformed and damaged under the influence of mining,and there is a large number of fissures,which provides a precondition for the spontaneous combustion of coal pillar because of the constant infiltration of oxygen into the fissure.At last,from the example of concealed fire in the roadway pillar in 2394 face of Dong HuanTuo coal mine,the measures of shallow water injection and shotcrete have achieved good effect,so that the co can be controlled effectively and the safe production of mine is ensured.The research results provide a theoretical reference for the similar situation in mine,which has a certain guiding significance to the prevention and control of similar concealed fire in mine.