Understanding sampling disturbance and behaviour of structured clays through constitutive modelling

The effects of sampling disturbance on structured clays with initial states above the oedometric Intrinsic Compression Line (ICLoe) are investigated numerically by applying a modified form of the Ideal Sampling Approach (ISA) and an elasto-viscoplastic constitutive model. The main features of the behaviour of structured clays during and after sampling reported in the technical literature can be replicated. Notwithstanding the inevitable damage to the microstructure of the “nominally undisturbed” specimens, the reconsolidation procedures commonly applied in laboratory practice are confirmed to be beneficial, even where they are not conceptually justified, as is the case of the SHANSEP approach. While it is possible to determine the strength and compressibility of “ideal” specimens from numerical interpretation of laboratory tests on “nominally undisturbed” specimens, the problems related to their direct use in conventional simplified design approaches for stability and settlement predictions are highlighted.