Secondary Development of a Thermo-Elastoplastic Constitutive Model for Saturated Clay in ABAQUS

Some projects, such as application of energy piles, underground storage of nuclear waste, geothermal development and laying of heat pipes, are necessary to consider the effect of temperature on the mechanical properties of clay. Test results have shown that clay may show two different phenomena: the shear strength of soil increases (thermal hardening) or decreases (thermal softening) with an increase in temperature. In order to describe these two different thermo-mechanical behaviors of clay, a new thermal elastoplastic constitutive model of saturated clay, in which the influence of temperature on pre-consolidation pressure and critical state parameter M of clay are taken into considerations, is proposed based on sub-loading modified Cam-clay model. The secondary development of the new model on ABAQUS was completed by preparation of the UMAT material subroutine. Through comparing the theoretical results with test results, it is known that the proposed constitutive model is capable of describing the thermal hardening and thermal softening behavior of clay well. And the correctness of the proposed constitutive model was verified. Finally, based on the proposed model, the generating mechanism of the thermal hardening and thermal softening behavior of clay are discussed macroscopically in terms of the influence degree of temperature on pre-consolidation pressure and critical state parameters.