Influence of hydraulic hysteresis on effective stress in unsaturated soils

In this note, results from a careful programme of experimental research are presented examining the variation of the effective stress parameter along main drying and wetting paths and in transition from drying to wetting. Both dimensional and non-dimensional representations of the results are discussed and the general trends observed are highlighted. A simple model is presented for the quantification of the contribution of suction to the effective stress of the solid skeleton including the hysteresis effects due to wetting and drying. In addition, it is shown that the degree of saturation may not be a suitable candidate as the effective stress parameter for such quantification.