A Case Study on the Installation of 4800 Helical Piles on a Remote Site in Northern Manitoba

KW Bannister

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: FOUNDATION DESIGN - IV Helical Piles

ABSTRACT: A camp to accommodate up to 2000 workers for construction of Keeyask Generating Station was built in a remote area of northern Manitoba. The camp consists of several three-storey dormitories and other support buildings. Geotechnical investigations consisted of helicopter-accessed probes and hand auger borings prior to road access, supplemented during site development with land-based geotechnical explorations. The site is located within the Canadian Shield in a region of discontinuous permafrost. The design-build contractor selected high strength helical piles for the foundation system. A preconstruction test program evaluated the feasibility of this pile alternative and developed installation criteria. Additional static pile load tests were conducted during production, to verify the preconstruction tests and address unanticipated subsurface conditions that were encountered. Over 4800 piles were installed. At the height of construction, the contractor utilized three piling rigs and worked 24 hours/day to meet the project schedule. The pile design was governed by uplift loading due to adfreezing forces and lateral wind loads. This paper presents a description of the site conditions, a summary of challenges encountered during construction, and summary of results from the 12 lateral and 9 tensile static load tests that were performed for the project.

RÉSUMÉ: Hydro a été bâti dans une région éloignée dans le nord du Manitoba. Ce camp consiste de plusieurs dortoirs à trois étages ainsi que des bâtisses de soutien. Des investigations géotechniques sont composées de sonde accessible par hélicoptère erniers ont été compléter pendant le développement du site avec des explorations géotechniques à terre. Le site a lieu dans une région de pergélisol discontinu dans le Bouclier Canadien. La conception-construction a sélectionné des colonnes hélicoïdes pour duction pour vérifier ces programmes avant la construction et a adresser les conditions rencontrer de subsurface non-prévu. Plus de 4800 colonnes et a travaillé 24 -pression dû aux forces de géli-adhérence et de vent latéral. Ce papier présent une description des conditions du site, un aperçu des défis rencontrés pendant la construction et un résumé des résultats des 12 latérales et 9 contraintes de traction des tests de charge statique effectuer pour le projet.

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