Ph.D Thesis

Ph.D StudentEinav Itai
SubjectApplications of Thermodynamical Approaches to Mechanics
of Soils
DepartmentDepartment of Civil and Environmental Engineering
Supervisors ASSOCIATE PROF. Konstantin Volokh
PROF. Alexander Puzrin


This research focuses on the applicative aspects of thermomechanical approaches to constitutive modeling of soils, using the frameworks of Hyperelasticity, Hyperplasticity, and Continuous Hyperplasticity. Except for Hyperelasticity, attention in these frameworks has been chiefly focused on the theoretical aspects, while the applicative side has been neglected. Although this thesis is not lacking in theoretical or numerical efforts, the main objective of the thesis is to try and close a part of the theoretical-practical gap. Towards this end, the thesis tries to answer three major questions: (A) Is it possible to construct competitive models within rigorous thermodynamical approaches? (B) If there are theoretical differences between rigorous and non-rigorous frameworks, what are the imposed restrictions on constitutive modeling? (C) If restrictions exist, how do they affect the predictions of stress-strain curves and solutions of geotechnical boundary value problems (BVP's)? The answer for these questions is accompanied to development of a novel computational algorithm for automatic constitutive modeling. The routine is utilized for automatic developments of thermodynamically admissible constitutive models and predictions of BVP's.

Another major contribution is the unification of the thermodynamical frameworks of hyperplasticity and continuous hyperplasticity, which allows modeling new materials without loss of thermodynamical generality. This, together with an establishment of a tool for modeling kinematic hardening regions for different stiffness variation types, facilitates the development of a new Continuous Hyperplastic Critical State model. The model shows relatively high success rates in estimations of experimental data both from triaxial testing and different BVP's.