Effective stress and water pressure in saturated clays during heating–cooling cycles

Abstract

Experiments with heating and cooling cycles in undrained constant total stress conditions in triaxial apparatus are presented. Heating induces a large pore-water pressure increase, which eventually leads to a large irreversible strain and possible mechanical failure. Subsequent cooling produces a drop in water pressure. In one test the drop during cooling was more than two times higher than the previous increase during heating, reaching values of up to 2.30 MPa. An analysis of these findings in terms of a thermoplastic model is presented. The interpretation of these tests relies heavily on the kind of stress-partitioning hypothesis that is used. It was found that the described phenomena can be quantitatively dealt with using the classical effective stress principle, if the shear strength and consolidation are described in terms of temperature-dependent plastic yield limit. Key words : temperature, plastic strains, effective stress, pore pressure.