A viscoplastic model including anisotropic damage for the time dependent behaviour of rock

Abstract

SUMMARYThis paper presents a new constitutive model for the time dependent mechanical behaviour of rock which takes into account both viscoplastic behaviour and evolution of damage with respect to time. This model is built by associating a viscoplastic constitutive law to the damage theory. The main characteristics of this model are the account of a viscoplastic volumetric strain (i.e. contractancy and dilatancy) as well as the anisotropy of damage. The latter is described by a second rank tensor. Using this model, it is possible to predict delayed rupture by determining time to failure, in creep tests for example. The identification of the model parameters is based on experiments such as creep tests, relaxation tests and quasi-static tests. The physical meaning of these parameters is discussed and comparisons with lab tests are presented. The ability of the model to reproduce the delayed failure observed in tertiary creep is demonstrated as well as the sensitivity of the mechanical response to the rate of loading. The model could be used to simulate the evolution of the excavated damage zone around underground openings.

A thermodynamically consistent framework for saturated viscoplastic rock-materials subject to damage

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“…(25) described in case 1. Using the procedure proposed by Lemaitre and Chaboche (2001) and followed by Pellet et al (2005), the viscoplastic dissipation potential of a virgin material is defined from a load surface depending on the first and second stress invariants and q. Its expression is inspired from Lemaitre's dissipation potential ϕ * L ( , k/ vp ):…”

A new rheological model and its application in mountain tunnelling

“…Many researchers have contributed theirs pioneering works on this issue (Pellet et al, 2005;Bhandari and Inoue, 2005;Shao et al, 2006). Generally, the dissipation potential consists of two independent potentials, which correspond to the strain softening (i.e.…”

Nonlinear visco-elastic and accelerating creep model for coal under conventional triaxial compression

“…The other method is to adopt new theory (such as fracture and damage theory etc.) to construct creep model of rock (Grgic et al 2003;Enrico and Tsutomu 2001;Pellet et al 2005;Fabre and Pellet 2006;Sterpi and Gioda 2009). The proposed rheological models by the above two methods can all describe the accelerating creep stage of rock material.…”