Undrained cavity expansion analysis with a unified state parameter model for clay and sand

This paper presents a new analytical solution for undrained expansion of spherical and cylindrical cavities in soils with a unified state parameter model for clay and sand (CASM). Large strain and effective stress solutions are derived for soils in the elastic, plastic and critical-state regions. The key advantage of using the state parameter model CASM is that it can model both clay and sand and is generally able to capture overall soil behaviour as observed in the laboratory. The newly developed solution provides the stress and strain fields during the expansion of a cavity from an initial to a final radius. Following the validation with the original Cam Clay solution, a simple parametric study is conducted to investigate the effects of key model parameters on stress distributions and cavity expansion curves. Applications to the analysis of pile installation and self-boring pressuremeter tests highlight some important implications in geotechnical practice.