ii This thesis presents constitutive theories for finite deformation of homogeneous, iso-tropic thermoelastic solids in Lagrangian description using Gibbs potential. Since con-servation of mass, balance of momenta and the energy equation are independent of the constitution of the matter, the second law of thermodynamics, i.e. entropy inequality, must form the basis for all constitutive theories of the deforming matter to ensure thermody-namic equilibrium during the evolution [1, 2]. The entropy inequality expressed in terms of Helmholtz free energy is recast in terms of Gibbs potential. The conditions resulting from the entropy inequality expressed in terms of Gibbs potential permit the derivation of constitutive theory for strain tensor in terms of conjugate stress tensor and the constitutive theory for the heat vector. In the work presented here, it is shown that using the conditions resulting from the entropy inequality, the constitutive theory for the strain tensor can be derived using three different approaches: (i) assuming the Gibbs potential to be a function of the invariants of the conjugate stress tensor and then using the conditions resulting from

ent land plasticity model accounting for the effect of fabric and its evolution is used in the finite element analysis bserve ilure o ards s These studies identified the following key factors which influence and the drainage conditions. However, relatively less attention has been paid to the correlation of strain localization with the pres-ence of fabric and its evolution in sand. The fabric in sand, or the so-call internal structure of sand attributable to the sand particle orientation, contact normal distribution and void space distribu-tion, has been widely regarded to affect the key behavior of sand including dilatancy, liquefaction and critical state, and may of shear band depends crucially on the initial fabric orienta bric in san rent defor stages of sand. The change of internal structure in soil due to evolution may apparently affect the initiation and developm shear band. This has indeed been proved by micromechanics studies including distinct element simulations (e.g., Bardet and