A new analytical solution method of water inrush risk for an inclined coal floor above a confined aquifer

The risk assessment of water inrush from mining floors above confined aquifers has important theoretical and practical significance for safe mining operations and sustainability. At present, the risk assessment methods of water inrush from the floor are mostly based on the mathematical assessment theory which lacks physical process information that can reflect the mechanism of floor water inrush. Therefore, in this study, a new analytical solution method for assessing water inrush risk from the inclined mining floor of a coal seam above a confined aquifer is proposed. First, considering the factors of mine pressure, confined water pressure, and coal seam dip angle, a mechanical and analytical model of the stress distribution in the mining floor along the inclination of a coalface is established. Subsequently, the failure characteristics of the inclined mining floor along the inclination of the coalface are investigated using the Mohr–Coulomb criterion and on-site measurement. Then, a criterion to determine the location of the effective water-resisting layer and the water inrush from the inclined mining floor is deduced based on the thin plate theory, and applied for the risk assessment of water inrush in the 330301# coalface. Finally, considering the failure characteristics of the mining floor along the coalface’s strike, the spatial characteristics of the failure of the inclined mining floor are analyzed. Furthermore, the influence of the coal seam’s dip angle on the water inrush position from the floor is discussed.