Experimental studies on fragmentation of rock falls on impact with rock surfaces

Rock fall is a common natural hazard causing significant damage to infrastructure and loss of life. Rock fragmentation is frequently observed during rock fall events and several authors have raised issues related to the impact of fragments on the protection structure. However, this phenomenon is not accounted for when designing the protection barriers. The paper presents the results of 20 rockfall tests performed in a quarry in Italy to provide new insight into the fragmentation phenomenon, especially in the case of foliated materials. The results have shown that the impacting angle plays a key role in the fragmentation of foliated rocks whereas the effect of the impacting energy tends to be of second order. No threshold in impacting energy could be defined to explain what triggers the fragmentation. It has been noticed that the proportion of impacting energy dissipated during fragmentation is relatively constant and depends on the choice of the normal restitution coefficient.