Viscous behaviour of St-Roch-de-l'Achigan clay, Quebec

This paper describes the viscous behaviour of St-Roch-de-l'Achigan clay, a Champlain Sea clay from Quebec, Canada. The general geotechnical profile of the soil deposit was first established with static cone penetration tests, vane tests, and some laboratory tests performed at different depths. For the study of the viscous behaviour of the clay, a special laboratory test program was established for specimens taken at depths from 4.8 to 5.8 m. This program included special incremental loading oedometer tests, constant rate of strain (CRS) oedometer tests performed at different strain rates, isotropic and anisotropic triaxial compression tests, and undrained shear tests. All these tests were performed under a constant temperature, varying from 10 to 50 degreesC. The test results show that the vertical yield stresses and the entire limit state curve depend on strain rate and temperature. The critical state line is also temperature dependent in the void ratio (e) - log principal effective stress (p') diagram but not in the deviator stress (q) - principal effective stress (p') diagram. The results also show that microstructuring may develop when the temperature is high or the strain rate small.