Quantification of the effects of structure on the compression of a stiff clay

A detailed analysis was made of the compression behaviour of London Clay from oedometer tests, investigating the effects of the clay structure through comparisons between the behaviour of the intact soil and that of the same soil in a reconstituted state. The normalizing parameters commonly used in the literature to analyze the effects of structure on the compression behaviour of clays were found not to represent accurately the real behaviour of those clays that have a gradual yield in compression and require very high stresses to reach and cross the intrinsic compression line. For these soils, it is often difficult to identify a clear yield stress and the effects arising from the structure of the intact material may be concealed by the effects arising from the sample depth and the curvature of the intrinsic compression line at high stresses. A new normalizing parameter is introduced that refers the compression of the natural soil to the intrinsic swelling behaviour and the intrinsic compression line of the material. This was found to better represent the enhanced resistance of the intact material in compression while not requiring numerous loading and unloading stages in the oedometer tests as required by other methods. © 2008 NRC Canada.