Experimental study on posture evolution and load transfer mechanisms of hydraulic supports in steeply dipping stopes based on digital twins

Safe and efficient mining of steeply dipping coal seams (35°–55°) constitutes a pivotal challenge for global energy supply, arising from the complex coupling effects between mining equipment instability and roof strata dynamics. To mitigate the frequent instability of hydraulic supports in such complex environments, this study establishes a novel Digital Twin-driven experimental framework. This framework integrates large-scale (1:5) physical similarity experiments with FLAC3D numerical modeling to elucidate the spatiotemporal posture evolution and multidimensional load transfer mechanisms of the "support-surrounding rock" system. The results demonstrate a non-linear degradation in support stability as the inclination angle increases. Notably, at a critical inclination threshold of 65°, the self-stabilizing capacity of the support is compromised, resulting in irreversible toppling (7.1°) and severe roof fragmentation. Under dynamic loading conditions, a distinct asymmetric load transfer pattern is identified where back-push and lateral impacts induce a directional load migration toward the up-dip section of the shield beam. This generates high-stress concentrations at articulated hinge points, peaking at 29 MPa, and triggers cascading instability from the up-dip to down-dip supports. Based on these mechanical insights, stability-oriented optimization measures, specifically active base-lifting mechanisms and reinforced side guards, are proposed. This work provides a robust theoretical basis for optimizing mining equipment to ensure continuous and safe energy extraction in complex geological settings.