Soil-water coupled finite deformation analysis

Theoretical basis of the soil-water coupled finite deformation analysis has been presented within the framework of finite deformation theory, critical state soil mechanics, subloading surface concept, effective stress principle and Darcy's law. Since the constitutive law is expressed in rate form, all the governing equations are thereof expressed in rate form. The essentials of the original Cam-clay model for finite deformation are reviewed with due consideration to the hardening/softening behavior of normally consolidated clays. For overconsolidated clays, the subloading surface Cam-clay model, in which the subloading surface concept is applied to original Cam-clay, is discussed in detail. In order to illustrate the applications of soil-water coupled finite deformation analysis, some numerical examples are presented on triaxial compression tests in which the tests are considered not as tests on a single soil element but as tests on soil mass with properly defined boundaries. The significance of elasto-plastic soil-water coupled analysis is also discussed through the numerical results comparing non-coupled and coupled analysis for two extreme cases: the fully undrained case and the fully drained case. These two extreme cases analyzed, reveal that the non-coupled analysis cannot yield unique solutions independent of mesh size and incremental step size. The coupled analysis on the other hand yields approximate, yet unique solutions independent of mesh and step size.