Estimation of mean effective stress in clay soils

This paper proposes a simple method for estimating the horizontal effective stress in clay soils, from which the mean effective stress can be determined. It is shown that the method is applicable to a wide range of clay soils with varying stress histories, including normally consolidated and heavily overconsolidated clays. Although this paper is expected to be of use to many practitioners in the field of geotechnical engineering, it also has a particular relevance with respect to the effects of moisture abstraction on shrinkable clay soils by vegetation, or simply by seasonal variations. While the effects are well known, the methods for identifying clay desiccation and for calculating heave potential are often relatively expensive, and the results can be inconclusive. Using the proposed method, this paper describes a simple and low-cost alternative method for estimating the in situ mean effective stress in desiccated clay soils. This information can be used to confirm the likely depth of clay desiccation, and provides a means of calculating a further estimate of heave potential.