Three kinds of basic structures of working face in near horizontal coal seam

Based on the mechanical effect and the movement rule of overlying strata of coal seam during coal extrac- tion,this paper investigates the phenomenon of pressure arch and structural arch,and the relationship between struc- ture arch and pressure arch,and proposes three forms of pressure arch in coal mine. According to theoretical analysis, similar simulation and numerical simulation,the working face in near horizontal coal seam is divided into the rock sup- port structure,the rock pressure movement structure and the protective structure of working face,which are respectively referred to as “large structure”,“small structure” and “micro structure”. The relationship between the concrete form of the three kinds of basic structure and the behavior of mine pressure are studied in this paper,and thus the relation- ship between coal pillar and large structure is obtained. Finally,in terms of the shield crushing accidents during the coal pillar in the lower coal seam of shallow buried close distance coal seams is mined out,the causes of the accident are studied from the changes of three basic structural forms of the working face before and after the shield crushing ac- cidents,and thus its control measures are proposed.