The apparent shear strength of rock discontinuities is lower than that of small scale samples. At the same time, the sliding behavior is characterized, in situ, by marked instabilities. Numerical algorithms permit to calculate contact forces at any point, and to describe the stick-slip transition. On the other hand, the critical aspects are not captured by classical theories. Multiscale simulations show that the contact domain between rough surfaces is a lacunar set. This explains the size-dependence of the apparent friction coefficient. By applying an increasing tangential force, the regime of partial-slip comes into play. However, the continuous and smooth transition to full-sliding predicted by the Cattaneo-Mindlin theory is not occurring in real situations. We implement a numerical renormalization group technique, taking into account the redistribution of stress consequent to partial-slip. This permits the critical value of the tangential force to be found. The critical force is less than the one predicted by Coulomb’s theory, and depends on the specimen size and on the topology of the interface.

Multiscale modelling of stick-slip transition of rough (fractal) surfaces / Chiaia, Bernardino; BORRI BRUNETTO, Mauro. - ELETTRONICO. - 539-543:(2007), pp. 2594-2600. (Intervento presentato al convegno THERMEC 2006, 5th International Conference on Processing & Manufactoring of Advanced Materials tenutosi a Vancouver, Canada nel July 4-8, 2006) [10.4028/www.scientific.net/MSF.539-543.2594].

Multiscale modelling of stick-slip transition of rough (fractal) surfaces

CHIAIA, Bernardino;BORRI BRUNETTO, Mauro
2007

Abstract

The apparent shear strength of rock discontinuities is lower than that of small scale samples. At the same time, the sliding behavior is characterized, in situ, by marked instabilities. Numerical algorithms permit to calculate contact forces at any point, and to describe the stick-slip transition. On the other hand, the critical aspects are not captured by classical theories. Multiscale simulations show that the contact domain between rough surfaces is a lacunar set. This explains the size-dependence of the apparent friction coefficient. By applying an increasing tangential force, the regime of partial-slip comes into play. However, the continuous and smooth transition to full-sliding predicted by the Cattaneo-Mindlin theory is not occurring in real situations. We implement a numerical renormalization group technique, taking into account the redistribution of stress consequent to partial-slip. This permits the critical value of the tangential force to be found. The critical force is less than the one predicted by Coulomb’s theory, and depends on the specimen size and on the topology of the interface.
2007
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/1434256
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