Challenges with Pile Design and Construction on the Coquihalla Highway

Extreme rainfall events in November 2021 caused significant damage to several bridges on the Coquihalla Highway in British Columbia, Canada. As a result of the devastation, the Juliet Bridge needed to be replaced within a compressed timeframe in order to re-open to its full capacity. Due to the emergency nature of the work, site investigations were carried out immediately, including mud rotary boreholes and instrumented Becker penetrations Tests. Problematic low plastic glacial lacustrine soils were encountered in the foundation soils. The bridge was designed with deep piled foundations that extended into the glacial lacustrine soils. During initial pile driving for the first bridge (northbound), the shaft resistance was determined to be much less than assumed in the design. Piles were re-tested between three days and nine days after the initial drive with minimal increase in shaft resistance. Due to schedule constraints, the piles were driven to a denser glacial till layer at depth. The schedule for the second bridge (southbound) allowed for a 142-day re-strike test to be carried out on one of the piles for the new bridge. This allowed for a significantly longer setup period to be tested. This paper focuses on the key challenges faced in the design and construction of the piles and presents the pile driving data obtained during this project.