Coefficient of restitution and rotational motions of rockfall impacts

By K. Chau, R. Wong, J. J. Wu. 2002

326 citations recorded by the source corpus.

Abstract This paper presents experimentally obtained results for the coefficient of restitution for spherical boulders impacting on rock slopes. Plaster modeling material is used for casting both the boulders and slopes. It is observed that the normal component of the coefficient of restitution ( R n ) increases with the slope angle α , which agrees with Wu's observations (Trans. Res. Rec. 1–5 (1985) 1031). However, there appears to be no clear correlation between the tangential component of the coefficient of restitution ( R t ) and the slope angle α . When the ratio of the resultant velocities and the ratio of the kinetic energies before and after impacts are used to define the coefficient of restitution (i.e. R V and R E ), a very clear increasing trend in the coefficient of restitution with α is observed. When all data are plotted onto the R t − R n space, our laboratory data fall into the rock slope regime proposed by Fornaro et al. (In: D.G. Price (Ed.), Proceedings of the Sixth International Congress IAEG, Amsterdam, Balkema, Rotterdam, 1990, p. 2173) and also agree with those data gleaned from literature. In addition, the rotational kinetic energy E r , induced at each impact, increases with the slope angle α , achieves a maximum at about α =40°, before decreasing again to a negligible value at α =70°. A simple theoretical model is proposed to explain this observation based on the locking between the boulder and the slope during impact. The α -dependence of E r differs from the recommendation by the Japanese Railway Association that the induced rotational energy is about 10% of that of the translational kinetic energy.

Subfields: Biomedical Engineering, Computational Mechanics, Management, Monitoring, Policy and Law

View Paper: https://www.semanticscholar.org/paper/6d25cb315ddad61239e96e11aa277a4ca5f84555

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Citations in the corpus

COLLISIONS BETWEEN GRAVITY-DOMINATED BODIES. I. OUTCOME REGIMES AND SCALING LAWS (2011, background): “Each body has ∼ 104 particles; in the inelastic bouncing phase, each particle has a normal coefficient of restitution, n = 0.5, and a tangential coefficient of restitution, t = 1, consistent with field observations and friction experiments on rocky materials (e.g., Chau et al. 2002).”
Geotechnical and kinematic parameters affecting the coefficients of restitution for rock fall analysis (2012, methodology): “[7] conducted laboratory tests using plaster for casting both blocks and impact surfaces.”
VELOCITY-DEPENDENT CATASTROPHIC DISRUPTION CRITERIA FOR PLANETESIMALS (2009, background): “Inelastic collisions between spheres are governed by a normal restitution coefficient of 0.2–0.8 (nominal value of 0.5) and no surface friction (Chau et al. 2002).”
Comparison of three Gis-based models for predicting rockfall runout (2003, methodology): “Instead, these model parameters were estimated on the basis of the land-cover map in combination with published data (Pfeiffer and Bowen, 1989; van Dijke and van Westen, 1990; Kobayashi et al., 1990; Giani, 1992; Azzoni et al., 1995; Chau et al., 1998, 2002; Meißl, 1998).”
Laboratory Investigation on High Values of Restitution Coefficients (2011, background): “Laboratory studies tend to produce the usually low values of restitution coefficients (Labiouse and Heidenreich 2009; Chau et al. 1999, 2002; Wu 1985).”
Full numerical simulations of catastrophic small body collisions (2008, background): “materials constrain the value of n (Chau et al., 2002).”