Coupled FEM/DEM modeling for the pull-out failure of corroded rockbolt

Corrosion of rockbolt significantly affects the long-term performance of anchoring structures. The pull-out behavior is a reference of the most practical significance for the design and assessment of rockbolt. Existing research normally uses reduced mechanical parameters to analyze the anchoring performance of corroded rockbolt. This paper presents a novel FEM/DEM coupling numerical method for investigating the pull-out failure of corroded rockbolt. Corrosion products are modeled as a layer of particles, and rock, grouting materials and rockbolt are modeled as bulk. The pull-out experiments of corroded rockbolt are carried out. The pull-out stress–displacement curves from experiments are employed for the calibration of rust parameters. Further, unified parameters of rust particles are used to model the effects of corrosion and confining pressure on the pull-out failure of rockbolt. It has been found that, as the corrosion development, the thickness of the corrosion layer grows thicker, which causes the degradation of bond strength and critical displacement. When corrosion degree increases from 0.62 to 4.83%, the bond strength and critical displacement decrease by 68.6% and 80%, respectively. Moreover, the larger the confining pressure is, the effect of corrosion on the strength reduction is more significant. This study provides a simple and feasible way to model the pull-out failure of corroded rockbolt.