An Elastic Visco-Plastic Model for Soft Soil with Reference to Radial Consolidation

The viscous nature of soft soil means it exhibits time-dependent stress-strain behaviour that affects its long term settlement and pore water dissipation. A novel mathematical model developed using the Peaceman-Rachford ADI scheme (P-R FD Scheme) can describe the visco-plastic behaviour of soft clay with a non-Darcian flow function; this model is a combination of the basic radial consolidation equation developed by Barron and Bjerrum\u27s time-equivalent (Bjerrum, 1967) concept that incorporates Yin and Graham\u27s (1989b) visco-plastic parameters. The settlement and excess pore water pressure obtained from this model are then compared with pre-existing models such as a Class C prediction for the Ballina trial embankment. This elastic visco-plastic model gives better results in terms of settlement and pore water pressure with the field data, although the excess pore water pressure that did not dissipate after one year is mainly due to the piezometers becoming biologically and chemically clogged in terrain with acid sulphate soil (ASS)