Le COR et la perte d’énergie de diverses combinaisons de grains et de blocs de base sont étudiés, y compris les grains de sable de Leighton Buzzard (LBS) de forme assez régulière comme sol naturel et le granit ou caoutchouc comme blocs de base, à part l’utilisation de matériaux artificiels pour les grains (billes d’acier au chrome, billes de verre) et les blocs (acier inoxydable, laiton). Dans cette étude, un nouvel appareil micromécanique de chargement par impact construit sur mesure est présenté, ainsi que des expériences d’impact sur des matériaux naturels et artificiels. Le coefficient de restitution (COR) est un paramètre d’entrée important dans la simulation numérique des flux granulaires, car il régit la distance de déplacement, l’étalement latéral et la conception des barrières. This is due to the variation of the elastic and morphological characteristics among individual LBS grains. Compared to glass balls and chrome steel balls, greater scatter in the COR values is observed for natural sand grains. However, within the narrow range of composite surface roughness of the tested grain–block interfaces no particular trend was observed in the COR values. For the tested grain–block combinations, lower values of COR were observed for impacts between materials of low values of composite Young’s modulus. In all the test combinations, the higher and lower values of the COR are found for granite block (ranging between 0.75 and 0.95) and rubber block (ranging between 0.37 and 0.44) combinations, respectively.

The repeatability of the new micromechanical impact loading apparatus was checked by impacting chrome steel balls on stainless steel block. The COR and energy loss of various grains and base block combinations are studied, including fairly regular-shaped Leighton Buzzard sand (LBS) grains as a natural soil and granite or rubber as base blocks, apart from the use of engineered materials for the grains (chrome steel balls, glass balls) and blocks (stainless steel, brass). In this study, a new custom-built micromechanical impact loading apparatus is presented along with impact experiments on engineered and natural materials. The coefficient of restitution (COR) is an important input parameter in the numerical simulation of granular flows, as it governs the travel distance, the lateral spreading, and the design of barriers.

Coefficient of restitution