The laboratory measurement and interpretation of the small-strain stiffness of stiff clays

The techniques and procedures used in advanced triaxial tests to measure the small-strain stiffness of stiff clays are reviewed. Differences between reported datasets for the stiffness characteristics of London Clay and the scatter within these datasets are shown to be the result of details regarding: apparatus configuration, particularly the connection between the internal load cell and the sample top platen; instrument and signal conditioning resolution; the ratio of shearing axial strain rate to preceding creep strain rate; and the approach taken to data interpretation, including normalisation.