Research on failure characteristics of goaf floor in the inclined coal seam based on the fracture mechanics

Abstract

Floor failure is the leading cause of mine water inrush after coal mining above the confined aquifer. Therefore, the prediction of floor failure depth is an important content of mine water prevention. The mining-induced failure depth and goaf floor characteristics are researched to grasp the goaf failure condition after the inclined coal seam mining with the theoretical analysis method. The inclined coal goaf floor's stress solving mechanics mode is set up based on the fracture mechanics theories. According to the Mohr-Coulomb criterion, the floor failure depth solving the equation is derived. With the theoretical analysis of the floor failure characteristics during the inclined coal seam mining, (1) the maximum failure depth of floor is nonlinear to the coal seam dip and the lateral pressure coefficient; the working face length, mining depth and floor cohesion positively correlate with the failure range; the floor cohesion is reversely proportional to the failure range. (2) There appears asymmetry in the layout of stress and plastic zones in the inclined coal goaf floor. Failure range and depth in-floor plastic zone increasingly enlarge when the coal face advances.