Theoretical Calculation and Numerical Simulation of Floor Failure Depth in Coal Mining Above High-Pressure Karst Aquifers

North China-type coalfields have gradually entered deep mining operations, facing severe threats from the Ordovician limestone aquifer at the base of the coal-bearing strata. The evaluation of water inrush risks in deep coal seam mining floors is the final barrier ensuring the safe extraction of working faces. The failure depth of the mining-disturbed floor, as a key evaluation indicator, directly influences the prediction of water inrush risks. Based on the engineering geological context of the No. 16 coal seam mining in the 10th Mining District of Xinyi Coal Mine, this study integrates theoretical analysis and numerical simulation to construct a prediction model for mining-induced failure depth under the condition of an ultra-thick Ordovician limestone aquifer base. Through comparative analysis of multiple methods, the differential characteristics of floor failure depth parameters at various mining step distances were obtained, revealing the spatiotemporal evolution laws of floor rock failure induced by mining. This research findings can provide theoretical support for the safe exploitation of deep resources in North China-type coalfields.