A New Application of Gangue Waste in Coal Mine for Reinforcing Strip Coal Pillar

In this paper, a new application of gangue watse in coal mine for reinforcing strip coal pillar was introducted, which is that filling walls made of gangue concrete are filled on both sides of the strip coal pillar for improving the performances and bearing capacity of strip coal pillar. The reinforcing mechanisms and reasonable parameters (strength and size) of filling walls were studied. And the reinforcing effects of filling walls made of gangue concrete were simulated and analyzed using FLAC3D software. The reinforcing role of filling walls mainly acts as the lateral restraint at the strip coal pillar. Meanwhile, filling walls with a certain strength can cut off a certain height of roof rocks at goaf side and the combined bearing body of the strip coal pillar, filling walls and the broken roof rocks in goaf is formed for supporting overlying strata, sharing the bearing loads of the strip coal pillar. The strength and size of the filling wall should meet the controlled conditions to ensure the reforcing effects. In the simulation, the strength of the filling wall of gangue concrete satisfied the theoretical calculation strength, and the size was taken as 3 m for the convenience of research. The simulation results show that the yielding zones of strip coal pillar have a carrying capacity again and the lateral deformation of the strip coal pillar is limited. And its bearing capacity is enhanced, preventing its further damage. And the stress distribution of the strip coal pillar nearly leveled off, and the filling wall was stable with small lateral deformation, and only a small part occurred yield failure. The above achievements provide a new approach to use of the gangue and have important significances for mining area environment.