IMPACT OF SALT CONTENT ON THE DYNAMIC STABILITY OF CHAMPLAIN CLAY

ABSTRACT: Champlain clay originally contained marine salts in its pore water, which contributed to its stability by fostering a flocculated particle structure. Electrostatic attraction between negatively charged clay surfaces and positively charged salt ions held the particles together. Over time, freshwater infiltration dissolved and leached these salts, increasing particle repulsion and causing the flocculated structure to collapse into a dispersed arrangement. This process significantly reduces the clay's strength and increases its sensitivity. The dynamic behavior of Champlain clay is particularly problematic during earthquakes. The shaking disrupts the fragile soil structure, causing rapid strength loss and liquefaction-like behavior. To investigate the effect of salt content on its dynamic stability, a series of dynamic simple shear tests were conducted in the GHD High Complexity Geotechnical Laboratory. The results demonstrated that higher salt concentrations stabilize the clay structure, reducing sensitivity and the risk of sudden strength loss. Salt also enhances the clay’s ability to dissipate excess pore water pressure during and after dynamic events, mitigating the risk of quick clay behavior. These findings highlight the critical role of pore water chemistry in the stability of Champlain clay and provide insights for geotechnical engineering practices in regions underlain by these sensitive soils.