Peak shear strength of compacted GMZ bentonites in saline solution

• Published in: Engineering geology Vol. 251; pp. 93 - 99
• Main Author: Xu, Yongfu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 09.03.2019
• Subjects: GMZ bentonite; Modified effective stress; Mohr-Coulomb criterion; Osmotic suction; Peak shear strength; Saline solution; Peak shear strength; Mohr-Coulomb criterion; Osmotic suction; GMZ bentonite; Saline solution; Modified effective stress
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2019.02.009

Knowledge of the peak shear strength of compacted bentonites is of fundamental importance to high-level nuclear waste repositories, as it forms the basis of the analysis of repository stability. The shear strength properties of GMZ bentonites are throughout investigated by undrained direct shear tests with different concentrations of NaCl solutions, and are explained in the light of the modified effective stress concept, which takes into consideration of the osmotic suction. The modified effective stress concept is expressed as p’ = p + π(p/π)Ds-2, incorporated with the normal stress (p) and osmotic suction (π) based on the bentonite surface fractal model. The peak shear strength behavior of GMZ bentonites in NaCl solutions appears to be explained satisfactorily by the modified effective stress. According to the Mohr-Coulomb criterion, the peak shear strength of bentonites saturated by distilled water and NaCl solutions is expressed by the same unique line in the τ-p’ plane. GMZ bentonite has the same values of the peak friction angle and the peak cohesion in distilled water and NaCl solutions of different concentrations. •Peak shear strength of bentonite expressed by modified effective stress according to the Mohr-Coulomb criteria•A modified effective stress expressed as p′ = p + (p/π)Ds‐2π, incorporating with osmotic suction (π)•The surface fractal dimension (Ds) of GMZ bentonite measured using the nitrogen adsorption isotherm.