Molinari A., Perfettini Hugo. (2017). A micromechanical model of rate and state friction : 2. Effect of shear and normal stress changes. Journal of Geophysical Research : Solid Earth, 122 (4), p. 2638-2652. ISSN 2169-9313.
Titre du document
A micromechanical model of rate and state friction : 2. Effect of shear and normal stress changes
Journal of Geophysical Research : Solid Earth, 2017,
122 (4), p. 2638-2652 ISSN 2169-9313
In this paper we analyze the influence of shear and normal stress changes on frictional properties. This problem is fundamental as, for instance, sudden stress changes are naturally induced on active faults by nearby earthquakes. As any stress changes can be seen as resulting from a succession of infinitesimal stress steps, the role of sudden stress changes is crucial to our understanding of fault dynamics. Laboratory experiments carried out by Linker and Dieterich (1992) and Nagata et al. (2012), considering steps in normal and shear stress, respectively, show an instantaneous response of the state variable (a proxy for the evolution of contact surface in our model) to a sudden stress change. We interpret this response as being due to an (instantaneous) elastic response of the plastic and elastic contacts. We assume that the anelastic response of the plastic contacts is frozen during sudden stress changes. The contacts, which were driven by plasticity before the stress change, are elastically accommodated during the sudden variation of the load. On the contrary, when the loading is slowly varying, elastic deformation of plastic contacts can be neglected. Our model is able to explain the evolution law for the state variable reported by Linker and Dieterich (1992). Plain Language Summary In this paper we analyze the influence of shear and normal stress changes on frictional properties. This problem is fundamental as, for instance, sudden stress changes are naturally induced on active faults by nearby earthquakes. Our model is able to retrieve the Linker and Dieterich evolution law, which is a reference one that describes the evolution of friction under variable normal stress. Our model assumption is that the plastic contacts that accommodate friction on a fault have an instantaneous elastic response to sudden changes in shear and normal stress. This allows the extrapolation of our frictional model to fault scale.
Plan de classement
Sciences fondamentales / Techniques d'analyse et de recherche [020]
;
Géologie et formations superficielles [064]
