A THERMOVISCOPLASTIC CONSTITUTIVE MODEL FOR CLAYS

The effect of heat on clay behaviour is characterized by non-linearity and irreversibility. Due to the complex influence of temperature, the rmomechanical factors have to be taken into account for the numerical simulation of the behaviour of such materials. A cyclic thermo-viscopl astic model is developed for this purpose, It includes thermal hardeni ng and the evolution of yield surfaces with temperature. From the phys ical point of view, it is built on the basis of available experimental results for a temperature range in which no phase change occurs. Conc eptually, it is the generalization of an isothermal multimechanism cyc lic model. A thermoplastic formulation of the model is also derived. T he results obtained from numerical simulations compare well with exper iments. (C) 1997 by John Wiley & Sons, Ltd.