Design of equipment system and surrounding rock control for N00 mining method without coal pillar left and roadway excavation

The N00 mining method without coal pillar left and roadway excavation is a new method developed in Chi⁃ na，which has some advantages in improving the rate of resource recovery，reducing the amount of roadway excavation， and eliminating the stress concentration caused by coal pillar. To further promote the development of this method，the core design idea of the N00 mining method is summarized from the aspects of mining face layout，surrounding rock control and equipment system based on the industrial test of this mining method in the Ningtiaota coal mine. In view of the surrounding rock structural characteristics of the N00 mining method，the de⁃ sign method for surrounding rock control is proposed，considering the overall stability of surrounding rock spatial struc⁃ ture during the whole movement process. That is using the rock crack⁃expansion to balance the pressure and using the dynamic and static coupling support to control surrounding rock. Based on this， three control objects， four control technologies， eight design standards and related design contents are defined. Simultaneously， based on the design concept of “integration of mining and retention”of the N00 mining method，the design of the N00 mining equipment system and the N00 roadway forming equipment system is formed，and the key structure and function de⁃ sign contents of the N00 equipment system are clarified. The test results show that using the N00 mining method，the coal cutter can complete mining under the condition of no roadway in front of the mining face，the synchro⁃ nous formation of roadway can be realized in the mining process，and the excavation of roadway in advance and coal pillar retention are on longer needed，which breaks through the traditional mining equipment separated layout mode. In the roadway retention stage，the maximum roof deformation is 145 mm，which fully meets the safety requirements. The successful application of the N00 mining method in the Ningtiaota coal mine verifies the feasibility of the method， and provides a new way to improve the recovery rate，save coal resources，reduce roadway excavation，reduce mining cost，and overcome the contradiction between mining and excavation.