Research On Height Of Water Flowing Fractured Zone Of Slice Excavation In Extremely Thick Coal Seam Of Barapukuria Colliery In Bangladesh

Strata movement and fracture of surrounding rock after coal excavation would cause water submerging the whole colliery when broken strata were exposed to underground or surface water. It’s not only a serious threat to the safety of coal production, but also causes serious damage for the mine ecological environment. It was necessary to get better understandings of mechanism of strata fracture, particularly height and distribution of flowing fracture zone after excavation.We adopted second slice excavation in extremely thick coal seams of Barapukuria colliery in Bangladesh as study area. Firstly mining and geological settings were clear and basic physical and mechanical properties of aquifer and aquifuge were gotten. With in-situ upward slant drilling plugging double-end testing monitoring for height of flowing fracture zone, results indicated that maximum height of flowing fracture zone was 61.46 m with 20.49 for max excavation ratio when hardness and fragility of strata without aquifer were obvious. Combining with physical and numerical simulation, the results were 70.68 m and 23.56. Moreover, distributions of flowing fracture zone between fully mechanized excavation and top-coal caving were given. All above considered, calculation methods of thickness of waterproof pillar in both conditions were provided.Relevant researches supported deeply study on mechanism of strata fracture in extremely thick coal seams, which was prerequisite for excavation under water in Barapukuria colliery.