Study on the Control Mechanism of Water-Resisting Performance in Deep High-Pressure Floor Strata

Abstract

As shallow coal resources become increasingly depleted, deep mining has emerged as an inevitable trend. However, floor water inrush disasters seriously restrict the safe and efficient exploitation of deep coal resources. The traditional water inrush coefficient method has limitations under the conditions of high in-situ stress, high confined water pressure, and strong mining-induced disturbances in deep mining, making it difficult to accurately reflect the hydraulic fracturing and conduits-forming failure mechanism of thick plates. To address this, based on the fluid-solid coupling theory, this study systematically investigates the influence of factors such as lithological combination, effective aquifuge thickness, fault structures, and aquifer water pressure on the failure depth and water-resisting performance of the floor using the FLAC3D numerical simulation method. The results indicate that the lithological combination plays a dominant role in floor stability, with the optimal water-resisting performance observed when the mudstone proportion is approximately 55%. The effective aquifuge thickness shows a positive correlation with the failure depth, but the presence of limestone interlayers exacerbates the failure. Increases in fault conductivity, dip angle, and thickness all significantly deepen the failure zone. For every 1 MPa increase in confined water pressure, the failure zone deepens by an average of 5 - 7 m, identifying water pressure as the key dynamic factor inducing water inrush. This study reveals the instability mechanism of hydraulic fracturing in deep mining floor strata, providing a theoretical basis for the precise prediction and prevention of mine water hazards.