CONVERGENCE BEHAVIOR - PACKING RELATIONS OF FULL EXTRACTION GATE ROADWAYS AT OAL LIGNITE MINE

This paper describes the results of convergence measurements conducted about five years for the re-use gate roadways at OAL lignite mine in Turkey. Double lignite seams separated with a marn layer, are mined wi th longwall retreating mining system at the mine. Rib pillar has been abandoned and gate roadways were planned to be packed for the re-use o f full extraction. Various packing systems have been attempted, namely three rows of wooden chock, one row of wooden chock plus concrete wal l and concrete wall only. The re-use of main gate roadways packed with wooden chock yielded 62% of closure. Lastly developed concrete packin g of 3 meters wide and specially developed support set composed of thr ee friction props and a cap, which is a modification of yieldable set, have successfully maintained the main and tail gate roadways stabilit y with a total vertical convergence of 32%. Good correlation has been established between pack stiffness and floor heave as well as maingate and tailgate convergences. The elimination of rib pillars by re-use o f gate roadways increased the coal recovery by 20% and decreased the d evelopment/production ratio from 0.065 m(3)/ton to 0.022 m(3)/ton.