Stability analysis of inclined bauxite pillar under goaf of coal seam considering principal stress rotation

• Principal stress rotation is most pronounced at the ends of the coal seam goaf, with maximum rotations of 19° (clockwise) and −40° (counterclockwise) in the bauxite layer. • Inclined bauxite pillars experience combined compressive and shear loading; clockwise principal stress rotation increases the shear-to-normal stress ratio, reducing pillar stability. • Pillars beneath the coal wall fail first due to stress concentration and principal stress rotation, potentially triggering cascading instability among adjacent pillars. • The study provides a theoretical basis and practical guidance for safe co-mining of coal seams and bauxite resources.