Evaluation of restitution coefficients concerning surface roughness

Rock fall phenomenon commonly occurs in excavation projects, road cuts and mining projects in the Queensland area, and it can cause safety problems, casualties and financial losses. In order to analyse rock fall, coefficients of restitution associated with energy dissipation during impact, have been widely used by many researchers. Despite the significant effects of surface roughness on rock fall analysis, far too little attention has been paid to explore a correlation between surface roughness and coefficients of restitution. This paper investigates the influence of surface roughness on the kinematic, normal and tangential coefficients of restitution. Several series of small-scale laboratory experiments were carried out, using natural rock and rock surfaces, characterized by different joint roughness coefficient (JRC). Also, various falling heights and surface inclinations were considered to assess the impact of surface roughness under particular circumstances. It was found that lower values of JRC led to a narrower range of the coefficients of restitution, whereas surface profiles with higher JRC values resulted in more scattered restitution coefficients owing to the more irregular geometry of the impact area