Rock pressure relief is the basic alternative for sustainable underground mining

Abstract

Retreat longwall mining is the most productive system for underground extraction of tabulated deposits. However, the steady growth of the mining depth dramatically increased the ground pressure in chain pillars protecting the longwall entries. Therefore, several coal industries have tried to shift to pillarless mining and practiced maintenance of the head or tail entry behind the longwall in the stress relief zones using the backfill bodies in the thin coal seams. We modernized the pillarless variant of the retreat longwall system introducing the third roadway, which is driven in the consolidated goaf behind the moving longwall in a stress relief zone. We used a computer code FLAC3D to simulate stress redistribution during pillarless extraction of adjacent panels that assisted to determine optimal parameters of mining layout. This modernized technology provides for sustainable mining due to enhancement of transport, ventilation, safety conditions, and a comfortable environment because of the stability of the underground roadways, which serve the high productive longwalls.