Modelling soil stratification under triaxial loading using critical state soil mechanics : technical paper

This paper compares the performance of critical state constitutive modelling with laboratory triaxial test data from a classic series of tests on reconstituted Weald clay. Critical state models used for predicting the test results include the original Cam-Clay model, Cam-Clay incorporating the planer Hvorslev surface on the dry side of critical and the Modified Cam-Clay model. The purpose of the comparison is to illustrate the dangers of using constitutive relations and models in numerical analyses without a proper understanding of their fundamental assumptions and inherent limitations. It will be shown that Modified Cam-Clay performs satisfactorily under the specific conditions of standard triaxial compression testing and that it fits experimental stress paths closer than the original Cam-Clay model. However, it is of utmost importance to include the Hvorslev state boundary surface on the dry side of critical for both these models if realistic predictions are to be made for heavily overconsolidated soils.