A constitutive model for granular materials with grain crushing

Manuela Cecconi, Antonio DeSimone, Claudio Tamagnini, and Giulia Viggiani

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Submission date: 23. Feb. 2002
Pages: 36
published in: International journal for numerical and analytical methods in geomechanics, 26 (2002) 15, p. 1531-1560 
DOI number (of the published article): 10.1002/nag.257
Bibtex
with the following different title: A constitutive model for granular materials with grain crushing and its application to a pyroclastic soil
PACS-Numbers: 62.20.Fe, 91.60.Ba, 61.43.Gt
Keywords and phrases: granular materials, plasticity, grain crushing
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Abstract:
A constitutive model for granular materials is developed within theframework of strain--hardening elastoplasticity, aiming at describing some of themacroscopic effects of the degradation processes associated with grain crushing. Thecentral assumption of the paper is that, upon loading, the frictional properties of thematerial are modified as a consequence of the changes in grain size distribution.

The effects of these irreversible microscopic processes are described macroscopically asaccumulated plastic strain. Plastic strain drives the evolution of internal variableswhich model phenomenologically the changes of mechanical properties induced by graincrushing by controlling the geometry of the yield locus and the direction of plasticflow.

An application of the model to Pozzolana Nera is presented. The stress--dilatancyrelationship observed for this material is used as a guidance for the formulation ofhardening laws. One of the salient features of the proposed model is its capability ofreproducing the stress--dilatancy behaviour observed in Pozzolana Nera, for which theminimum value of dilatancy always follows the maximum stress ratio experienced by thematerial.