Stress-dependent hardening and failure surfaces of dry sand
Article first published online: 10 JAN 2012
Copyright © 2012 John Wiley & Sons, Ltd.
International Journal for Numerical and Analytical Methods in Geomechanics
Volume 37, Issue 8, pages 787–809, 10 June 2013
How to Cite
Ehlers, W. and Avci, O. (2013), Stress-dependent hardening and failure surfaces of dry sand. Int. J. Numer. Anal. Meth. Geomech., 37: 787–809. doi: 10.1002/nag.1121
- Issue published online: 15 MAY 2013
- Article first published online: 10 JAN 2012
- Manuscript Accepted: 8 OCT 2011
- Manuscript Revised: 7 OCT 2011
- Manuscript Received: 14 FEB 2011
- cohesionless frictional material;
- stress-dependent hardening and failure;
- conventional and path-dependent triaxial experiments;
- inhomogeneous failure-based boundary-value problems;
- class file
During several triaxial compression experiments on plastic hardening, softening, and failure properties of dense sand specimens, it was found on various stress paths that the size of the failure surface was not constant. Instead, it changed depending on the current state of hydrostatic pressure. This finding is in contrast to the standard opinion consisting of the fact that the failure surface remains constant, once it has been reached during an experiment or in situ.
In general, the behaviour of cohesionless granular-material-like sand is somehow characterised in between fluid and solid, where the solid behaviour results from the angle of internal friction and the confining pressure. Although the friction angle is an intrinsic material property, the confining pressure varies with the boundary conditions, thus defining different solid properties like plastic hardening, softening, and also failure.
Based on our findings, it was the goal of the present contribution to introduce an improved setting for the plastic strain hardening and softening behaviour including the newly found yield properties at the limit state. For the identification of the material parameters, a complete triaxial experimental analysis of the tested sand is given. The overall elasto-plasticity concept is validated by numerical computations of several laboratory foundation- and slope-failure experiments. The performance of the proposed approach is compared with the standard concept of a constant failure surface, where the corresponding yield surfaces are understood as contours of equivalent plastic work or plastic strain. Copyright © 2012 John Wiley & Sons, Ltd.