The package, written in collaboration with Dr David Wood of CUED provides the description and analysis of soil response that could occur in a conventional triaxal apparatus.
The user must state past stresses which have given rise to the present condition of the soil, the present stress state, the desired final stress state of the soil, which will not always be reached, the drainage conditions, and optionally, the strain at which the test is to stop. The program plots the predicted stress paths and stress-strain curves, indicating the separate elastic and plastic portions of the path and providing 3D views of the path in stress-volume space.
Students find it difficult to grasp the model and the key to this understand- ing is the idea of thinking in terms of parallel paths in p':q stress space and p':V compressive space. With this package students are able to see the onset of plastic deformations in the stress strain curve, the consequences of passing though the current yield locus and they can see the link between p':q space and p':V space as the current yield locus and the current volumetric unloading-reloading line change in step with one another. Graphs can be examined in detail and numerical values obtained using a mouse and zooming facility.
Within the constraints of an elasto-plastic strain hardening model the more advanced students may input different geometries for the yield locus shape and vary the stress dilatancy relationship, additionally the parameters describing the soil may be changed by the user (shear modulus, slope of critical state line etc.), allowing the user to investigate the importance of various parameters on the stress-strain path.