ABSTRACT

The influence of water content and plasticity index is less certain in the literature. Given that the rate dependent response is linked to the viscosity of the water present in the pores of the clay and the absorbed water envelope of the clay particles (Low 1961) it might be expected that higher water contents would lead to more pronounced increases due to viscous behaviour. The increased thickness of the absorbed water envelope present in high plasticity clays may also lead to higher viscosity, where the envelope itself is thought to be more viscous than the free water in the pores. This reasoning is generally supported in the data presented by Briaud & Garland (1985), compiled

from some 150 undrained laboratory tests, although it should be noted that the available data at higher values of water content and plasticity index are somewhat limited.