Macro-meso fatigue failure of bimrocks with various block content subjected to multistage fatigue triaxial loads

•Cyclic triaxial increasing-amplitude loading tests were performed on bimrocks.•Multiple interface damage-cracking and volumetric dilatancy were impacted by block content.•The strain rate analysis reveal the instability precursor of bimrock using volumetric strain rate.•CT images highlight the meso-structural changes and mesoscopic failure mechanism was revealed.