Application study of narrow coal pillars along goaf in large mining height fully-mechanized top-coal caving roadway

In order to study the pressure control of the dynamic pressure roadway along the roadway with narrow coal pillars in the fully mechanized top coal caving mining face，this article takes the return roadway of No.130205 large mining height fully mechanized caving face in 2-2 extra-thick coal seam of Yangchangwan Coal Mine of Ningmei Group as the engineering background. It is impossible to maintain the excavation roadway with the full cross-section anchor cable support of the 35 m protection lane coal pillar in the original roadway.A narrow coal pillar study was performed under section conditions. A combination of on-site measurement，numerical simulation，and theoretical prediction was used to establish a mechanical structure model of the internal and external stress fields of the surrounding rock of the roadway. FLAC3D was used to simulate 5，6，8，10，and 15 m coal pillars with different widths in the return airway. Stress distribution of surrounding rocks. The theoretical calculation of the internal stress field is in the range of 9.5～10.3 m，and the reasonable width of a narrow coal pillar is 5.14～5.56 m; numerical simulation shows that 0～10 m is a low stress area，10～14 m is a stress peak area，and 14～45 m is a high stress value. In the area and slow-down area，after 45 m，the original rock stress gradually increases，and the supporting pressure in the coal pillars is distributed in a single peak. The size of the coal pillars for the protection lane is determined through research to be 6 m. According to the field application，the maximum deformation of the two sides during the mining of the 6m narrow coal pillar air return roadway is 241 mm，and the maximum deformation value of the top and bottom plates is 92 mm. The roadway support design is reasonable，the narrow coal pillar grouting effect is significant，and the narrow coal pillar roadway. The production requirements were fully met during the extraction.