Laboratory investigations on geotechnical characteristics of sensitive clay foundation: a case study of a mine tailings stack

ABSTRACT: Eastern Canada has substantial deposits of sensitive clay in southern Québec and southeastern Ontario. Sensitive clays have the potential to rapidly lose their shear strength if remolded, which makes them prone to potential landslides. These landslides have the potential to retrogress under certain circumstances, with significant soil strength loss which results in the soil behaving like a viscous liquid. To ensure the best possible performance of infrastructures built on this type of soil, a precise assessment of the strength and compressibility response of the sensitive clay is necessary. Inaccurate estimates may have a significant impact on the stability and settlement estimates of the site infrastructure prior to construction and may result in corrective remedial work during construction, which adds to the project duration and cost. This paper aims to present a detailed geotechnical characterization of a sensitive clay foundation which exists at the Éléonore Mine filtered tailings storage facility (TSF), located in James Bay, Québec, Canada. Accordingly, laboratory test results from intact clay samples were interpreted to quantify the geotechnical properties of the foundation clay. Obtained results from oedometer tests, monotonic triaxial and simple shear tests, and cyclic direct simple shear tests were analyzed and compared to the clay data already available in the Québec region. The findings in this study should be helpful to the engineering practice to support and improve the assessment of sensitive clay behaviour.