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Durham University

Department of Engineering

Staff Profile

Publication details for Dr Ashraf Osman

Osman, A. S & Birchall, T. J. (2014), Modelling tertiary creep in geomaterials using a continuum damage mechanics approach, in Soga, Kenichi, Kumar, Krishna, Biscontin, Giovanna & Kuo, Matthew eds, International Symposium on Geomechanics from Micro and Macro. Cambridge, UK, CRC Press, London, 705-708.

Author(s) from Durham

Abstract

Tertiary creep is often observed in soft rocks and it represents a problem in a mining environment.
Tertiary creep behaviour appears due to progressive micro cracking of the material and would result in a
loss of strength and stiffness, which may eventually lead to failure and a complete loss of load carrying capability
of the material. In this paper, the authors combined the continuum damage mechanics within the framework
of hyperplasticity, thus encompassing viscoplasticity and damage within a single theory. The authors
present a family of models which obeys the laws of thermodynamics. The entire constitutive behaviour is derived
from two scalar potentials; a free energy potential which provides the elasticity law, and a dissipation
potential which provides the yield function, the direction of plastic flow and the evolution of a damage variable.
No additional assumptions are required. These new models require only few parameters which have physical
meanings and are capable of capturing tertiary creep observed in soft rocks.