A unique Critical State two-surface hyperplasticity model for fine-grained particulate media

Coombs, William M.; Crouch, Roger S.; Augarde, Charles E.

doi:10.1016/j.jmps.2012.08.002

Cited by 15 publications

(14 citation statements)

References 44 publications

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“…Note that the yield surfaces are oblique with a fixed inclination without hardening in the models of Ohta and Hata and Sekiguchi and Ohta . Recognizing of the importance of rotational hardening during shearing, various forms of rotational hardening rules have been proposed to simulate more realistic behaviors of anisotropic clays …”

Section: Introductionmentioning

confidence: 99%

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

Chen

Yang

2019

Num Anal Meth Geomechanics

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Summary A bounding surface model is formulated to simulate the behavior of clays that are subject to an anisotropic consolidation stress history. Conventional rotational hardening is revisited from the perspective of thermodynamics. As the free energy cannot be accumulated infinitely upon critical state failure, the deviatoric back stress must vanish. This requires the rotated yield surface to be turned back to eventually align on the hydrostatic axis in the stress plane. Noting that most of the previous propositions violate this restriction, an innovative rotational hardening rule is formulated that is thermodynamically admissible. The bounding surface framework that employs the modified yield surface is applied to simulate elastoplastic deformations for overconsolidated clays, with which the overprediction of strength on the “dry” side can be greatly improved with reasonable results. Other important features, including contractive or dilative response and hardening or softening behavior, can also be well‐captured. It has been shown that the model can simulate three types of reconstituted clays that are sheared with initial conditions over a wide range of anisotropic consolidation stress ratios and overconsolidation ratios under both triaxial undrained and drained conditions. Limitations and potential improvement of the model regarding the fabric anisotropy at critical state have been discussed.

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Section: Introductionmentioning

confidence: 99%

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

Chen

Yang

2019

Num Anal Meth Geomechanics

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“…Following some earlier formulations,() the improved RH for the PPS rule evokes dependency on both the volumetric (

{\overset{ε}{true}}_{v}^{p}

) and deviatoric (

{\overset{ε}{true}}_{s}^{p}

) plastic strain increments. This is by no means a universally accepted proposition, as several RH rules have been proposed() that involve only

{\overset{ε}{true}}_{v}^{p}

.…”

Section: Improved Rh Rulesmentioning

confidence: 99%

“…Previous constitutive models() used the term I / I 0 (or the axisymmetric triaxial counterpart

p^{'} false/ p_{0}^{'}

) to diminish the rate of rotation when simulating the response of overconsolidated clays. To achieve a similar effect, other models() enclosed

{\overset{ε}{true}}_{v}^{p}

in Macauley brackets. However, in assessing the capabilities of the GBSM, it became evident that the accurate simulation of effective stress paths for C K 0 U E tests required a rather sizable acceleration in the rotation of the PPS toward the CSL in extension.…”

Section: Improved Rh Rulesmentioning

confidence: 99%

“…Having presented an improved RH rule for the BS, it is timely to briefly discuss the existence of an anisotropic state that results in a unique CSL in

e - \ln false(p^{'} false)

e - \ln false(I false)

space. Coombs et al referred to this as the “Critical Anisotropic State.” Dafalias and Taiebat recently stated that the issue of fabric evolution at critical state for clays is a debatable issue, largely because of the fact that precious little experimental evidence is available that can confirm or deny the existence of a CAS. It is thus not surprising that although some authors have introduced this concept into their RH rules,() a larger number have not.…”

Section: Critical Anisotropic Statementioning

confidence: 99%

“…Since these pioneering undertakings, several RH rules, possessing varying degrees of sophistication, have been proposed for cohesive soils. ()…”

Section: Introductionmentioning

confidence: 99%

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Improved rotational hardening rule for cohesive soils and definition of inherent anisotropy

Leal

Kaliakin

Mashayekhi

2017

Num Anal Meth Geomechanics

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Summary Improved, microfabric‐inspired rotational hardening rules for the plastic potential and bounding surfaces associated with the generalized bounding surface model for cohesive soils are presented. These hardening rules include 2 new functions, fη and fI0, that improve the simulation of anisotropically consolidated cohesive soils. Three model parameters are associated with the improved hardening rules. A detailed procedure for obtaining suitable values for these parameters is presented. The first 2 parameters affect the simulation of constant stress ratio loading where, because of the presence of fη, the third parameter is inactive. The second new function, fI0, accelerates the rotation of the plastic potential and bounding surfaces during shearing, which is particularly important for overconsolidated soils tested in extension. This paper also describes the proper manner in which to define the inherent anisotropy. This seemingly straightforward test has rarely been discussed in sufficient detail.

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Continuously unique anisotropic critical state hyperplasticity

Coombs

2016

Int. J. Numer. Anal. Meth. Geomech.

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Summary This paper presents the theoretical development and methodological motivation of a single surface anisotropic hyperplasticity model. The model extends the isotropic family of models developed by Coombs and Crouch by: (i) introducing anisotropic shearing into the yield surface, (ii) relating two of the material constants to a single physical quantity and (iii) using a more physically realistic pressure sensitive elastic free energy function. This model overcomes the difficulty of determining the constants of the isotropic two‐parameter surface by analytically relating them to a single experimentally measurable physical quantity, namely the normalised hydrostatic position of the Critical State. This provides a model with a Critical State surface that is constant throughout the loading process, invariant of the level of anisotropy inherent in the yield envelope. The model is compared with experimental data from triaxial tests on Lower Cromer Till, contrasted against the SANIclay model and the recent model of Yang et al. (2015) as well as being compared with rarely considered experimental data from hollow cylinder tests on London Clay. Copyright © 2016 John Wiley & Sons, Ltd.

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A unique Critical State two-surface hyperplasticity model for fine-grained particulate media

Cited by 15 publications

References 44 publications

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

Improved rotational hardening rule for cohesive soils and definition of inherent anisotropy

Continuously unique anisotropic critical state hyperplasticity

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