Research on the Key Technology of Gob-Side Entry Retaining by Roof Cutting for Thick and Hard Sandstone Roofs

In order to ensure the application of gob-side entry retaining by roof cutting for thick and hard sandstone roofs, key technology pre-split blasting was studied. The LS-DYNA used analyze effect energy-gathering pipe. Using methods theoretical analysis numerical simulation, it determined that optimal height 16 m angle 15°. pressure relief verified FLAC3D. It is proposed use deep-hole loosening solve problem with a being difficult collapse. A group loose holes designed be arranged every 20 in roadway. depth #1 blasthole 47 m, horizontal direction 20°; #2 65 field test carried out 7135 ventilation roadway Qidong Coal Mine China. on-site peeping results showed pipe had good directional slitting. After blasting, collapsed filled gob time. monitoring curves hydraulic support resistance working face side much smaller than without cutting, good.