We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.

Durham Research Online
You are in:

Continuously unique anisotropic critical state hyperplasticity.

Coombs, W. M. (2017) 'Continuously unique anisotropic critical state hyperplasticity.', International journal for numerical and analytical methods in geomechanics., 41 (4). pp. 578-601.


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.

Item Type:Article
Full text:(AM) Accepted Manuscript
Download PDF
Publisher Web site:
Publisher statement:This is the accepted version of the following article: Coombs, W. M. (2017) Continuously unique anisotropic critical state hyperplasticity. IInternational Journal for Numerical and Analytical Methods in Geomechanics, 41(4): 578-601, which has been published in final form at This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving. International journal for numerical and analytical methods in geomechanics.
Date accepted:28 July 2016
Date deposited:28 July 2016
Date of first online publication:20 August 2016
Date first made open access:20 August 2017

Save or Share this output

Look up in GoogleScholar