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a b s t r a c tRock 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.

Despite the significance of rockfall hazards in Australia, this phenomenon is still poorly characterized in many regional environments. In particular, the relationship between slope/rock properties and rockfall motion parameters needs to be better defined. In the context of rockfall prediction, it is important to quantify the normal and tangential restitution coefficients (referred to as k n and k t) and the equivalent rolling coefficient (µ), which are site-specific. Several series of rockfall tests have been conducted in three different geological environments in New South Wales. The results of the tests show a large variability of the motion parameters, which is due to the natural variability of the blocks and to the randomness of the impact positions. Also, values of k n consistently and systematically higher than the benchmark values from the literature have been inferred. Despite there being no clear correlation between the restitution coefficients and the rotational energy, this latter is believed to be at the origin of such results.

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