Deeply weathered tertiary basalt rocks occur along many major highways and rural roads of New South Wales (Australia) and the nature of the associated rockfall hazard is poorly characterized. In order to quantify the restitution coefficient in this specific geological situation, real scale rock fall tests were performed on a natural slope derived from basalt rock. The slope, with an average inclination of around 22 degrees, was covered by scattered rock and vegetal debris of variable size. During the tests, the motions of 21 blocks were recorded to estimate the pre- and post-impact velocities with the objective to quantify the normal and tangential restitution coefficients kn and kt . This paper presents the preliminary results of these series of tests. They include the restitution coefficients determined for 10 blocks and a study of rotational and translational energy for 4 blocks.


Deeply weathered tertiary basalt rocks predominate along the major highways and rural roads along the Great Dividing Range of New South Wales (Australia). In spite of the main importance for safety for road and highways in such environments, the nature of the associated rockfall hazard in these environments is poorly characterized. In particular, no quantitative values of restitution coefficients are available. The restitution coefficients are a necessary input in most numerical rockfall codes to estimate the energy acquired by a block during its travel. Typical values of restitution coefficients for different natures of impacted surface are available in the literature (Piteau and Clayton, 1976; Pfeiffer and Bowen, 1989,Azzoni and de Freitas, 1995). However, these data are somehow incomplete since other factors such as block shape, mass and velocity – to name a few – tend to affect the values of the restitution coefficients as discussed by Giani (1992) and Labiouse and Heidenreich (2009).

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