David Elwood: Edmonton LRT Tunnels

Edmonton LRT Tunnels – A History and Comparison of Tunnel Performance in the City

The City of Edmonton has been building tunnels for drainage and transportation purposes since the early 1950’s. Initially the tunnels were primarily constructed using hand excavation methods supported by rib and lagging, but the methods have now shifted to more modern construction using Tunnel Boring Machines as well as conventional SEM tunnel techniques. The presentation will give a brief history of the surficial geology of the city and their general performance as well as a history of the types of tunnels typical constructed in Edmonton; what the predominant failure mechanisms are and how the construction methods have been adapted to accommodate the failures. This will include a brief discussion regarding the difficulties in predicting an appropriate shear strength or permeability and more importantly, what parameters are appropriate and when. This discussion will look at how the face is typically controlled through the highly variable, glacially derived soils and what the displacements manifested at the ground surface typically look like. Finally, case studies will be presented of the previous and current LRT subway tunnels in the city will also be presented including comparing and contrasting the geology, construction methods and the associated ground movements.

PRESENTER DETAILS

David Elwood, P.Eng.

David Elwood is an assistant professor in the Department of Civil, Geological and Environmental Engineering at the University of Saskatchewan. He holds a M.Sc. in Geological 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, site investigations and advanced soil mechanics. David’s research is primarily on in situ testing and site characterization as well as characterisation and the performance of heavily overconsolidated soils and shales.