Boundary distribution of top-coal limit-equilibrium zone in fully mechanized caving in steeply dipping coal seams

In fully mechanized caving mining, the earlier top coal enters limit-equilibrium zone, easier it is for leakage to be induced in front of support. As dip angle seam increases, support drastically reduces stability stope support–surrounding rock system. this study, theoretical analysis, a physical simulation experiment, numerical simulation, and field measurements were performed consider influence effect on gradual deterioration first time, quantitative characterization limit equilibrium boundary was realized based analysis continuous damage medium mechanics. The results show that two boundaries exhibit consistent, asymmetric ‘double arch’ distribution along incline. inclined upper-middle region working face enter state, whereas upper lower regions lag behind. initial final zone are distributed from 1.24 3.04 m 0.19 −1.95 wall, respectively. verified by times face. These could provide reference information evaluating systems mining with steeply dipping seams.