Canadian National Railway (CN) completed a 2nd track construction over deep muskeg along an existing mainline on the Bala Subdivision between Mile 29.2 and 29.5 in Aurora, Ontario in 2017. The site contains peat in depth up to 10m (33'). The use of helical piles with a reinforced soil platform was chosen as the supporting structure due to little or no settlements on the adjacent existing mainline during helical piles installation to allow continue train operation at all time. Multiple layers of geotextile over 560 helical piles were installed in stages prior to track construction. This paper will discuss the design options considered prior to construction, construction challenges and methodologies such as Fast Lagrangian Analysis of Continua (FLAC) used to determine the settlements due to the consolidation of the peat deposit during the different construction stages and predict the long-term settlements under train loading.
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