Research on the stratigraphic parameters of the floor multi-functional roadway under the strong mining of deep coal seams

Intense mining disturbances in deep, extra-thick coal seams readily induce severe deformation and instability in underlying multi-functional roadways, significantly compromising the efficacy of integrated mine disaster control. To mitigate the effects of strong mining-induced stresses and ensure surrounding rock stability, this study systematically investigates the rational layout horizon of multi-functional roadways in the coal seam floor, using the Binchang mining area as the engineering background. A comprehensive approach integrating theoretical analysis, physical similarity modeling, numerical simulation, and field monitoring was employed. Results indicate that: (1) Theoretical calculation yields a maximum floor failure depth of 18.37 m, suggesting that the roadway should be positioned below this depth to avoid the directly damaged zone. (2) Physical similarity modeling reveals significant mining-induced stress perturbations and large surrounding rock deformations at depths of 30 m and 50 m, whereas the stress environment at a depth of 70 m tends to stabilize, exhibiting a gentle strain response. (3) Numerical simulations further corroborate these findings, demonstrating that at the 30 m level, roof-to-floor convergence reaches 1068 mm, indicating severe failure; at the 50 m level, floor heave attains 190.5 mm, posing substantial control challenges; conversely, at the 70 m level, the maximum floor heave is reduced to 159.5 mm, and the roof exhibits coordinated deformation, reflecting superior overall surrounding rock stability. Consequently, an optimal layout horizon of 60-70 m below the coal seam floor within a competent rock stratum is determined. Field implementation confirms that in roadways situated at this horizon, roof-to-floor convergence is generally less than 100 mm, roof separation is constrained within 30 mm, and stress fluctuations are minimal, thereby ensuring stable, long-term roadway operation.