Hydraulic Support Loading in a Deep Longwall Face with Large Dip and Advance Angles: Distribution Characteristics and Mechanical Interpretation

Deep longwall mining under large dip and advance inclinations can induce strongly asymmetric roof deformation and nonuniform load transfer, complicating the assessment of hydraulic support loading. Taking the 2902 working face of Chensilou Coal Mine as an engineering case, this study combines field monitoring, theoretical analysis, and FLAC3D simulation to investigate a recurrent M-shaped pressure distribution under a fixed geometry with dip and advance-direction inclinations of approximately 35°. Representative field profiles at cumulative advance distances of 40, 60, 80, and 100 m consistently exhibited an M-shaped hydraulic support pressure distribution. To interpret this spatial pattern, the main roof was represented as a bidirectionally inclined equivalent elastic plate with three clamped edges and one free edge, while the hydraulic support–immediate roof system was represented by a local Winkler foundation. The analytical solution identified two spatially separated roof-deflection concentration zones, and the FLAC3D results exhibited a broadly similar bimodal pressure tendency. The complete 28-day monitoring record was subsequently analyzed to examine whether the observed pattern persisted beyond the four representative advance stages, revealing two recurrent high-pressure sectors approximately within supports 45–75 and 105–135. The field, analytical, and numerical results showed approximate sector-level correspondence. This study therefore provides a case-specific mechanical framework relating recurrent zonal hydraulic support loading to spatially variable overburden loading, asymmetric equivalent boundary constraints, nonuniform main-roof flexure, and local roof–support load transfer.