Key technologies and management of arc section in full-mechanized caving face for "three soft" ultra-thick coal seam with large dip angle

At present, there are still some long-term unsolved problems in full-mechanized caving mining technology of "three soft" ultra-thick coal seam with large dip Angle at home and abroad. The main performance is that the mining equipment dominated by support will slide and fall under the condition of Angle above 38°, and the floor may also slide downward when it is damaged, which aggravates the instability of the "support - surrounding rock" system, and the large falling top coal and roof will slide and fill. The complexity of roof movement is increased, and the complex movement of the roof will inevitably affect the ore pressure appearance of the working face and the stability of equipment such as support. The advance support range of transportation and return air roadway is affected by moving abatement pressure, and the roadway convergence and deformation are fast, so it is necessary to expand and repair the bottom repeatedly. It is difficult to maintain effective section of roadway, difficult to control hydraulic support and sliding up and down, difficult to add or remove hydraulic support of working face, frequent production impact of full-mechanized mining equipment, and difficult to shift the tunnel end support area due to stress concentration. Taking some of the technical difficulties in the above problems as a breakthrough, and taking the 47407 full-mechanized caving face of Wangjiashan Coal Mine as the engineering background, based on the horizontal and circular transition full-mechanized caving mining technology of "three soft" ultra-thick coal seam with large dip Angle, combined with geological conditions and the current situation of the working face, the method of combining theoretical analysis and engineering practice has been adopted through long-term practical exploration. The key technology of the management of the circular section of the working face is summarized. The transportation roadway is arranged in the roof of the coal seam, and the return air roadway is misarranged in the goaf of the upper section and more than 2/3 of the floor rock is broken, which reduces the frequent expansion and repair of the upper and lower exits and the mining roadway. The lower section of the working face adopts the "arc-horizontal" transition arrangement. The paper puts forward the control and quantitative analysis of the production state and length of the working face based on the arc segment, the influence of the driving force and gravity of the shearer on the sliding down of the front slide based on the arc segment, the sliding down of the equipment adjusting the upper and lower cutting wall (slop) of the working face, the analysis and calculation of the sliding down of the equipment adjusting the working face using the arc segment The new methods of analysis and calculation, such as quantity analysis and estimation, have briefly analyzed and described the new experiential methods of working face production status, length control and quantitative calculation, working face equipment control, production status and engineering quality control based on circular arc segment. Up to now, three full-mechanized caving faces with large dip Angle have been mined by using this technology. It provides a new method for full-mechanized caving mining of large dip seam under "three soft" geological conditions.