Study of the bearing mechanism of the coal roof and the dimension selection of the room and pillar in the shallow and close distance coal seam

Abstract

Combinated the theoretical analysis and the field measurement,the model of the coal seam roof masonry structure for the issue of the coal roof bearing mechanism and the reasonable dimension adjustment of the room and pillar under the condition of the room and pillar goaf in the shallow and close distance coal seams were studied.It was presented that: the stress and movement characteristics universal model has been established for the masonry structure under the condition of the discontinuous and uniform load;the typical model has also been established about the stress and movement characteristics of the 'main roof-coal pillar-immediate roof-supports'composite structure system;the safe and reasonable dimension selection principle of the room and pillar under the condition of the room and pillar goaf in the close distance coal seams.The results show that the bearing and the breaking characteristics of the roof has been effectively improved when the reasonable dimension was adjusted or determined of the room and pillar.Through the comparison and analysis of the lower coal seam strata behavior regularity measurement under the condition of the room and pillar dimension changing of the upper coal seam in the context of the actual production in Shigetai coal mine,the reasonable dimension of the room and pillar finally determined to set at 6.0 m and 2.5 m.In this condition,the roof pressure characteristics of the lower coal seam face was significantly improved,the safe and efficient production was guaranteed.