ABSTRACT
In laboratory triaxial or shear tests, and in the ground, soil is loaded from some initial state and it will ultimately reach a critical state. (If the soil is clay it may go on to a residual state.) In Chapter 8 I described the behaviour of soils during isotropic and one-dimensional compression and swelling and I showed how these were related. If the history of isotropic or one-dimensional loading and unloading is known the initial state described by the current effective stress, specific volume and overconsolidation ratio are fixed. Notice that the conditions in a shear test when the shear stress is zero are the same as those in a one-dimensional compression test and the conditions in a triaxial test when q = 0 (i.e. when σ a = σ r) are the same as those in an isotropic compression test.
