Research On Breakage Regulation Of Floor And Forecast On Water Burst When Mining With Confined Water Under Floor

When mining coal above aquifer, water inrush from seam floor is frequent because of the influence of mining activity and confined water. The No.15 coal seam in a mine, a new consolidated colliery of Shanxi Coal Group, is with confined water under its floor, which is faced with serious threat of water inrush.This thesis analyses the main problem of No.15 coal seam based on the hydrogeology information of No.15 coal seam in Working face 1501, on the point of mining, is chosen as object of study. By constructing hydrological drill, the component and waterproof ability of floor is obtained, and the generalized geological section of working face 1501 is corrected. The cores are used in rock mechanics test. After comparing the effect factors of water inrush from working face floor, water pressure and water-resisting layer are selected as the main factors of floor breakage. The distribution of stress, displacement and plastic zone of floor is simulated by using FLAC3 D when working face 1501 is mined with confined water under its floor. As a result, when mining with confined water, the deepest breakage position is 10~14m under the floor, and the effect of water-resisting layer is stronger than water pressure. Plastic theory and empirical formula is used to analyze the deepest position of mining breakage, and the result is in accord with numerical simulation. The deepest beakage position is thought to be 15 m under the floor. The possibility of water inrush in workingface 1501 is forecasted by using water bursting coefficient method,“next three-zone” theory etc. It is concluded that the floor of workingface 1501 is stable, which is able to control water inrush, if there is no structures in the working face. While hydrological detection activities should still be strenthened, especially in areas with thin water-resisting layer, to prevent water inrush.