Laboratory investigation of the virgin drying of the Corinth Marl

Abstract

Marly formations are widespread in Greece with major works founded on, or excavated in them. Perhaps the most spectacular of them is the Corinth Canal, a ca. 7 kilometre long canal with very steep (average inclination 4.5: 1) and Corinth marl. The excellent stability of the steep canal slopes has motivated extensive laboratory investigations of the mechanical properties of the Corinth marl at the Geotechnical Department of the National Technical University of Athens since several years, the latest of which involved the drying properties of the Corinth marls. The drying portion of the soil-water characteristic curve was determined from undisturbed block samples and from reconstituted samples re-consolidated to the in-situ stresses. The airentry pressure was found to be higher in the case of the undisturbed samples compared to the reconstituted/re-consolidated samples. Furthermore, the variation of the void ratio with suction up to the air-entry pressure was found to be close to the curve of void ratio versus effective stress from one-dimensional consolidation over the same stress range. This behaviour constitutes evidence of the validity of the effective stress principle up to the air-entry pressure. Finally, the paper concludes with estimations on the apparent cohesion change of the Corinth marl with suction.