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:
Colin DregerMr. Dreger is a professional Geotechnical Engineer with over nine years of consulting experience in the geotechnical field in Alberta, British Columbia, Saskatchewan, Yukon, Northwest Territories, and Nunavut. He is currently engaged in a geotechnical doctorate program with the Civil and Environmental Department at the University of Alberta.
Colin enrolled in the Ph.D. program in 2020 and was subsequently seconded to the Site C Hydroelectric Development Resident Engineering Team during the Fall 2020 term to oversee production-scale lateral load testing of the Shaftesbury Shale. He has been exploring the constitutive behavior of argillaceous shales in collaboration with leaders in the energy sector and in-situ testing practitioners. His research will improve deformation models and design and construction methodologies by providing a framework to better understand observed deformation behavior, thereby informing risk. A practicable approach will be developed which uses high quality, relatively lower cost insitu and laboratory testing coupled to address complex rock mass behavior in evolving stress conditions.
Dr. Michael HendryDr. Hendry holds the Natural Sciences and Engineering Research Council Industrial Research Chair in Railway Engineering, is a Principal Investigator (PI) for the Railway Ground Hazard Research Program (RGHRP) (est. 2003, position since 2014), and is an Associate Professor of the Department of Civil and Environmental Engineering at the University of Alberta. Dr. Hendry leads research in rail transportation focusing on infrastructure assessment, cold climate performance, landslides, rock falls, soft subgrades and impacts of extreme weather events.
Dr. David ElwoodDr. Elwood is an Associate Professor in the Department of Civil, Geological and Environmental Engineering at the University of Saskatchewan. He holds an M.Sc. in Geotechnical Engineering from Queen’s University and a Ph.D. in Civil Engineering from the University of Alberta. David teaches a wide variety of geotechnical related courses at the University of Saskatchewan including foundation engineering, numerical modelling, geological engineering field school, site investigations and advanced soil mechanics. David’s research is primarily on in situ testing and site characterisation as well as characterisation and the performance of heavily overconsolidated soils and soft rocks.
David has published on the topic of soil mechanics, site instrumentation and in situ testing, site characterisation and is currently on the editorial board of the Canadian Geotechnical Journal. David was also the lead author for the Site Investigations chapter of the 2023 Canadian Foundation Engineering Manual. In addition, He has been an active consultant nationally and internationally for nearly 25 years and has extensive experience with site characterisation and development of material properties for a wide range of geo-materials. His research has focused on the characterisation of hard, overconsolidated soils and soft rocks for a variety of applications, including tunnelling, embankment construction, deep excavations, pit wall stability, shallow and deep foundations and slope stabilization.
