Effects of Pore Fluid Salinity on the Shear Strength of a Soft Clay

Abstract

The paper presents the results from a preliminary study focused on the influence of pore fluid salinity on the shear strength of a soft clay from New South Wales (Australia). Direct shear tests (DST) were carried out on natural specimens using pore fluids with different salt concentrations. Electrical conductivity measurements were performed on the squeezed pore water after shearing to quantify changes in salinity of the soil pore water. Strength parameters showed a clear dependency of the pore fluid. Changes in c’ and ’ appear to be controlled by two factors: (i) initial salinity, and (ii) extent of the concentration gradient. Results from mercury intrusion porosimetry tests demonstrated the influence of changes in pore water salinity on the evolution of the dominant pore size. It was in agreement with macroscopic observations. Implications for further laboratory testing are highlighted in the paper.