Effect of pore water chemistry on the hydromechanical behavior of poorly indurated Boom Clay (C-H-M coupling)

This thesis presents an investigation of the influence of salinity (Ionic Strengths: 0.015 M, 1.0 M, and 2.0 M) and sodium occupancy (60% and 90%) on the hydro-mechanical behavior of Boom Clay by combining a dedicated experimental campaign with the development of a chemomechanical constitutive modeling approach. The experimental program includes swelling pressure measurements under constant-volume conditions, salinization and desalinization tests under oedometric conditions, high-pressure oedometric tests, undrained shear strength tests, and microstructural analyses using mercury intrusion porosimetry. The results demonstrate that increasing salinity leads to a reduction in swelling pressure, an increase in shear strength, and modifications of the aggregate structure, especially at high ionic strengths, which also result in increased hydraulic conductivity. While the observed effects of ionic strength are qualitatively consistent with findings reported for other clay materials, the study provides new insights into the role of sodium occupancy—particularly its potential influence on interlayer spacing—in shaping the chemo-hydro-mechanical response of Boom Clay.