| The objective of this dissertation is to explore the application of continuum/FEM techniques to the soil slope stability analysis (SSA) problem. The classical SSA methods routinely used typically assume a Mohr-Coulomb strength criterion, and compute in-situ soil stresses using simple statics approximations. Taking advantage of numerous advances in the past two decades in soil constitutive modeling, in porous medium theories, and in nonlinear computational mechanics, the goal is to advance the state of the art in computational SSA.; To develop more powerful methods of SSA, porous medium models for soil are first implemented and tested. Such models are important for many slope stability problems due to relevant interactions between interstitial pore fluid and the soil skeleton, which can have significant effects on soil strength behaviours. Next, a unique, smooth, three-surface elastoplastic cap model is formulated, its numerical integration algorithm is developed, presented, and tested on a number of problems. The attractive aspect of presented cap models is that it features continuous coupling between a soil's volumetric and deviatoric plastic behaviors in an associative elastoplastic framework. This coupling effects can be quite important for the stability analysis of embankments constructed on saturated, normally consolidated, clay/silt soil deposits.; With this background in place, two basic complementary basic methods of SSA in a continuum/FEM framework are then presented, analyzed and compared. The first is the so-called gravity increase method, which involves gradually increasing the body force loading on realistic numerical slope models. The second method, the so-called strength reduction method, involves applying realistic body force loadings to a mathematical slope model while monotonically reducing the shear strength of the comprising soils.; For more general types of SSA including pore-pressure effects, the former method is shown to be extremely well suited to stability analysis of embankments constructed on soft saturated soil deposits, whereas the latter method is shown to be very well suited to problems in which unconfined steady state seepage is occurring in a slope system. |
