A Microcrack Based Continuous Damage Model for Brittle Geomaterials

Shao, Jian-Fu; Rudnicki, John W.

doi:10.4028/www.scientific.net/kem.177-180.103

Cited by 12 publications

(14 citation statements)

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“…This softening can be explained by damage mechanics due to the initiation, growth, and coalescences of microcracks that reduce the effective cross-sectional area, Figure 2. For more details, the reader is referred to numerous articles and books on damage mechanics [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The use of strain-softening material models leads to an ill-posed boundary value problem (BVP) [27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Computational Methods for Fracture in Brittle and Quasi-Brittle Solids: State-of-the-Art Review and Future Perspectives

Rabczuk

2013

ISRN Applied Mathematics

161

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An overview of computational methods to model fracture in brittle and quasi-brittle materials is given. The overview focuses on continuum models for fracture. First, numerical difficulties related to modelling fracture for quasi-brittle materials will be discussed. Different techniques to eliminate or circumvent those difficulties will be described subsequently. In that context, regularization techniques such as nonlocal models, gradient enhanced models, viscous models, cohesive zone models, and smeared crack models will be discussed. The main focus of this paper will be on computational methods for discrete fracture (discrete cracks). Element erosion technques, inter-element separation methods, the embedded finite element method (EFEM), the extended finite element method (XFEM), meshfree methods (MMs), boundary elements (BEMs), isogeometric analysis, and the variational approach to fracture will be reviewed elucidating advantages and drawbacks of each approach. As tracking the crack path is of major concern in computational methods that preserve crack path continuity, one section will discuss different crack tracking techniques. Finally, cracking criteria will be reviewed before the paper ends with future research perspectives.

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Section: Introductionmentioning

confidence: 99%

Computational Methods for Fracture in Brittle and Quasi-Brittle Solids: State-of-the-Art Review and Future Perspectives

Rabczuk

2013

ISRN Applied Mathematics

161

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“…However, they are basically phenomenological, and thus not sufficiently realistic for some demanding applications. As has been pointed out [5], their parameters are not clearly connected to physical mechanisms, especially to those of an oriented character. The models based on continuum damage mechanics employ the crack density tensor which characterizes the global damage due to cracks of all orientations.…”

Section: Introductionmentioning

confidence: 98%

“…Significant advances have been achieved [1][2][3][4][5][6] but a realistic and versatile model of broad applicability, suitable for large-scale numerical computations, is still unavailable.…”

Section: Introductionmentioning

confidence: 99%

“…Among the studies of contiguous rock located between the joints, two types of models may again be distinguished: (a) micromechanics of various physical mechanisms of inelastic deformation in the microstructure [2,3], and (b) the development of constitutive and fracture models on the macroscopic continuum level [4][5][6][7][8]. The objective of this study is to develop for isotropic porous rocks a model that is basically of the latter type but incorporates an approximate characterization of oriented physical mechanisms in the microstructure, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Microplane constitutive model for porous isotropic rocks

Bažant¹,

2002

Num Anal Meth Geomechanics

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SUMMARYThe paper deals with constitutive modelling of contiguous rock located between rock joints. A fully explicit kinematically constrained microplane-type constitutive model for hardening and softening non-linear triaxial behaviour of isotropic porous rock is developed. The microplane framework, in which the constitutive relation is expressed in terms of stress and strain vectors rather than tensors, makes it possible to model various microstructural physical mechanisms associated with oriented internal surfaces, such as cracking, slip, friction and splitting of a particular orientation. Formulation of the constitutive relation is facilitated by the fact that it is decoupled from the tensorial invariance restrictions, which are satisfied automatically. In its basic features, the present model is similar to the recently developed microplane model M4 for concrete, but there are significant improvements and modifications. They include a realistic simulation of (1) the effects of pore collapse on the volume changes during triaxial loading and on the reduction of frictional strength, (2) recovery of frictional strength during shearing, and (3) the shearenhanced compaction in triaxial tests, manifested by a deviation from the hydrostatic stress-strain curve. The model is calibrated by optimal fitting of extensive triaxial test data for Salem limestone, and good fits are demonstrated. Although these data do not cover the entire range of behaviour, credence in broad capabilities of the model is lend by its similarity to model M4 for concrete}an artificial rock. The model is intended for large explicit finite-element programs.

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“…Several authors [20,21] have shown that the geometrical properties of a given damage state can be correctly described by a second-order symmetrical tensor. The main limitation of this approach is that, in the most general case, the damage described has an orthotropic symmetry where the orthotropic axes are identified with the main directions of the damage tensor.…”

Section: Law Of Induced Anisotropic Damagementioning

confidence: 99%

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

Pellet

Hajdu

Deleruyelle

et al. 2005

Num Anal Meth Geomechanics

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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.

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A Microcrack Based Continuous Damage Model for Brittle Geomaterials

Cited by 12 publications

References 0 publications

Computational Methods for Fracture in Brittle and Quasi-Brittle Solids: State-of-the-Art Review and Future Perspectives

Computational Methods for Fracture in Brittle and Quasi-Brittle Solids: State-of-the-Art Review and Future Perspectives

Microplane constitutive model for porous isotropic rocks

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

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