Research on the Design of Roof Cutting Parameters of Non Coal Pillar Gob-side Entry Retaining Mining with Roof Cutting and Pressure Releasing

With the increasing tension of current coal resources and the increasing depth of coal mining in China, Non Coal Pillar Gob-side Entry Retaining Technology has become a preferred coal mining method in underground coal mines. In the current study of the non coal pillar gob-side entry retaining mining with roof cutting and pressure releasing, the theory and design of roof cutting under near-level conditions have formed a certain system. However, there is a lack of systematic research on the design of the roof cutting and the connection requirement of the cutting seam and other aspects about the inclined coal seam. Therefore, choosing the concrete representative target mines as the research foundation, using mechanics analysis, geometric analysis, numerical simulation and other means, on the basis of considering the change of mining height, this paper mainly studies about the effect of coal seam inclination on roof slit depth and angle, then get the three steps of the cutting height design, the three considerations of the roof cutting angle design and the connection rate requirement of the roof cutting. At last the key roof cutting parameters of the three target mines are calculated accordingly. Based on the existing research, this paper puts forward the concept and design method of roof cutting connectivity rate. The design system of roof cutting seam parameters of non coal pillar gob-side entry retaining mining with roof cutting and pressure releasing is further improved, and the corresponding calculation method is deduced for the design of the key parameters of the inclined coal seam and the gently inclined coal seam, and proposing the second roof cutting scheme of the upper side gob-side entry retaining.