3. AFR Mining Method and Key Technologies

In Chap. 3, the corresponding technologies were developed according to balance mining theory to achieve AFR without mine pillars. It mainly included in-situ drilling and zoning technology, high prestressed energy absorption control technology, directional roof cutting technology, and roadway gangue rib support technology. The specific meanings of core technologies are as follows. (a) This method utilizes in-situ drilling of surrounding rock to accurately partition the roadway roof, guiding roof cutting & support parameters design. (b) High prestressed energy absorbing support are used to assure the roadway roof's stability during the mining stages. (c) The gob roof is collapsed using mining pressure after determining the cutting direction, which severs the gob roof's physical link to the roadway roof quantitatively. The gob is filled with rock mass broken expansion, forming a stable gangue rib. (d) Maintain the AFR through the roadway gangue support system. Finally, this method eliminated the retention of mine pillars and automatically formed a roadway, while retaining the AFR for continued use in the next working face. Furthermore, this chapter provides the detailed introduction to the advantages and performance of each technology of AFR mining method through experimental methods.