Featuring the Future Webinar: Reducing uncertainty in argillaceous shale deformation models to support performance-based design

Performance-based design is anchored in predicting the serviceability deformations of a structure. This requires adequate knowledge of the deformation characteristics of the foundation material. With argillaceous shales constituting as much as 50% of the global sedimentary rock mass and outcrop in about one third of the emerged earth surface, shale formations often comprise the foundations of major civil developments. Sampling, testing, and consequently predicting deformations of these clay-rich shales based on laboratory testing is challenging as they rapidly deteriorate and experience irrecoverable damage when exposed. Moreover, their response to loading/unloading is complex and can vary considerably as a function of local stress history, dominant mineral variation, and scale. As part of a testing program at the Site C Dam project to assess foundation response, pressuremeter testing was conducted in the Shaftesbury Shales below the RCC buttress which supports the spillways and generating station on the Right Bank. This presentation will center around the pressuremeter testing procedures, data, key inferences, and instrument limitations. Interpreted variability in stiffness and deformation behavior will be discussed, including an assessment of sources of uncertainty.

Expected Outcomes for participants:

• Highlight the utility and limitations of pressuremeter testing in weak shales.
• Explore the factors influencing deformation behavior in argillaceous materials.
• Provide key considerations for practitioners investigating or modelling shales.

Date: Wednesday, May 29, 2024
Time: 2:00 PM to 3:00 PM ET

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