Thermomechanical approach to modeling constitutive behaviors of geomaterials

The thermomechanical approach to establishing elastoplastic constitutive model for geomaterials is introduced briefly. The major attraction of this approach is that it not only provides a tight mathematical structure, but also satisfies the laws of thermodynamics automatically. The whole of the constitutive structure (yield condition, flow rule, hardening laws and elasticity law) is determined just from two thermodynamic potentials (the free energy and the increment of dissipation function). It is demonstrated that, whenever the dissipation potential depends on the current stress; the flow rule is necessarily non-associated; and the concepts of friction and of non-associated flow rule are intimately linked. Then, some research advances, including three-dimensional problems, characteristic of geomaterials on micro and meso level, homogenization of stress-strain relation, dilation and anisotropy, are given. Several important concepts, such as "stored plastic work or frozen elastic energy" and "Reynolds-Taylor State", are explained and analyzed. Finally, some proposals for further research are made.