ONE-DIMENSIONAL CONSOLIDATION OF SATURATED-UNSATURATED COMPRESSIBLE POROUS MEDIA WITH VARIABLE TOTAL STRESS.

摘要

This study covers one-dimensional theories and numerical solutions to analyze the fluid flow and deformation in saturated and/or unsaturated deformable porous media with variable total stress.; For saturated porous materials, due to the decline of the water table, the total stress at points within the flow domain changes continuously. The separation of an initially coinciding water table, which serves as the upper boundary of the medium, and a surface consisting of a set of solid particles during the lowering of the water table and the compaction of the medium is taken into account. Following the development of a one-dimensional mathematical model consisting of a mass conservation equation, quasi-static equilibrium equations, stress-strain relations for an assumed perfectly elastic solid matrix, and a variable total stress expression, numerical solutions obtained by finite element method are presented for various problems of practical importance. These include compression of a saturated column with time dependent and constant displacement at the upper boundary, one-dimensional subsidence due to variability in total stress with a leakage from an underlying aquitard, and consolidation due to surface flooding. Variability of soil properties such as porosity and permeability is considered. The consolidation of a saturated very soft soil column due to self-weight is also analyzed.; In a similar way, a mathematical model is developed for an unsaturated deformable porous medium. The total stress variability is obtained in terms of change of moisture content. The problems solved by finite difference techniques include gravity drainage, capillary rise, and movement of infiltration front into a homogeneous and layered compressible porous medium. Different types of soils; i.e., sand and clay and different number of layers; i.e., two and three, are studied.; Under coupled flows, the two zones; i.e., saturated and unsaturated, are solved simultaneously to get a more rigorous solution for pore pressure and vertical displacement due to gravity drainage in a one-dimensional soil mass. The infiltration into a compressible salt marsh due to tidal inundation is also studied by employing this technique.