木元 小百合

An elasto-viscoplastic model for unsaturated expansive soil is developed. An evolutional equation is adopted to describe the absorption of water into the interlayer of clay platelets. In addition, the internal compaction effect caused by swelling of clay unit is expressed with the expansion of the overconsolidation boundary surface and the static yield surface. Based on the model, a one-dimensional finite element analysis is conducted to study the development of swelling pressure. Comparing the experimental results and the simulated results, it is found that the proposed model can reproduce the effects of dry density and the initial water content on the swelling behavior.

The last decades have shown a remarkable increase in the number of heavy rains, typhoons and earthquakes. These natural phenomena are the main causes for geohazards. As a result the mitigation of geohazards has become a major research topic in geotechnical engineering, and in recent years simulation-based predictions and monitoring tools have been developed to enquire the mechanisms underlying geohazards. This book is a comprehensive overview of these developments, and will be of interest to engineers, researchers, students in Civil and Environmental Engineering.

In the present study, a multiphase deformation analysis of a river embankment has been carried out using an air-soil-water coupled finite element method considering the unsaturated seepage flow. A numerical model for unsaturated soil is constructed based on the mixture theory and an elasto-viscoplastic constitutive model. The theory used in the analysis is a generalization of Biot's two-phase mixture theory for saturated soil. An air-soil-water coupled finite element method is developed using the governing equations for three-phase soil based on the nonlinear finite deformation theory, i.e., the updated Lagrangian method. Two-dimensional numerical analyses of the river embankment under seepage conditions have been conducted, and the deformation associated with the seepage flow has been studied. From the numerica/11 methods, it has been found that the seepage-deformation coupled three-phase behavior can be simulated well with by the proposed method.