Geotechnical properties of the Corinth Canal marls

Abstract

The Corinth Canal crosses the isthmus of Corinth and is of great importance for Mediterranean navigation as well as the railroad and highway connections between southern and central Greece. In the century-long history of the Canal, the slopes have shown only minor stability problems despite their significant length, very steep inclination and, more importantly, the strong earthquakes that have frequently shaken the Corinth area. This type of unsual behaviour has motivated research into the mechanical behaviour of the bluish grey marl which is the main geological formation in the Canal area. Geotechnical investigation of the Corinth Canal marl was performed with an extensive laboratory testing programme on high quality undisturbed samples of the intact marl. The material was shown to exhibit brittle behaviour, high stiffness and significant apparent cohesion at low and moderate stress levels. These characteristics indicate that the material possesses significant structural bonding which is believed to be due to cementation between individual particles, caused by the deposition of carbonates at the time of material genesis. With stressing, the material yields due to a gradual bond degradation. The locus of the initial yield points (yield surface) seems to be an ellipse oriented along the isotropic axis. The testing programme was supplemented with a series of tests on the de-structured marl obtained by thorough remoulding. These tests showed a significant difference in the pre-yield stiffness and the peak strength at low stress levels, but comparable post-rupture shear strengths.