Shape effects on the coefficient of restitution during rockfall impacts

Rockfall mitigation technique, such as rock fence, is extremely important in protecting Highway as well as residential buildings in many mountainous countries. In practice, rockfall simulation computer programs are commonly used for the acquirement of the required rockfall parameters. They include the probabilities of the horizontal and vertical travel distances of the probable rockfall events, the bouncing height at various positions along the slope, and the impact energy of rockfalls at location at which the mitigation devices are going to be installed. The most crucial input parameter that controls the final output of the rockfall statistics is the coefficient of restitution. This paper considers the shape effect of boulders on the coefficient of restitution, and it is found that the tangential component of coefficient of restitution is relatively insensitive to the shape of the boulder whereas the normal component of coefficient of restitution increases with the angularity of the boulders.