Numerical Study of Undrained 1D Compression for Unsaturated Soil

This paper presents a new numerical analysis method for one-dimensional, large strain compression of a single undrained, unsaturated soil element. The method builds on the framework of the consolidation model, CS2, which has been used successfully for many consolidation-related engineering applications. In this work, soil properties and relationships are used to model undrained compression from first principles. A numerical study is performed to investigate the effect of increasing applied total stress on element compression and corresponding soil properties. Results indicate that volume change is non-linear and, as the element approaches saturation, an increase in total stress yields a nearly equivalent increase in pore air pressure. Ultimately, this work will serve as a point of departure for the development of a new large strain consolidation model for unsaturated soil.