Unique advantages of Ductile Iron Piles distributed by DuroTerra, LLC (www.duroterra.com) for foundation support continues to spur growth and acceptance of the system on projects in the United States and Canada. Projects benefiting from the modular, low vibration driven micropile system span from Texas up to Canada. One such project is the West Harbour GO Station Retaining Wall project located in Hamilton, Ontario.
The project is part of the Metrolinx regional transportation plan – providing the Lakeshore West Line with train and bus service. The new station is an integral part of the proposed Hamilton Light Rail Transit enabling connection to the John C. Munro Hamilton International Airport. The station construction included a concrete segmental retaining wall running west from the Bay Street Bridge Abutment.
The project team considered various foundation options for the new 150-ft long retaining wall positioned adjacent to the active rail lines. Shallow foundations were ruled out due to the performance concerns with existing undocumented fill followed by loose sand and silt and soft to very stiff clay extending to glacial till at depths of 75 ft. A driven H-pile solution was initially selected and designed for 40 piles with a structural capacity (ULS) of 290 kips. However, the H-pile option was challenged with practical construction issues including excessive vibrations, extended working pad and laydown area requirements, access issues requiring excessive splicing of battered piles and variations in working grades causing challenges for installation equipment and inefficient pile material usage.
Engineers at GeoSolv Design/Build, Inc. (www.geosolv.ca) worked closely with the design team at IBI Group and the contractor (Kenaidan Contracting Ltd.) to propose a Ductile Iron Pile alternative to meet the performance needs while providing significant constructability advantages. The Ductile Iron Pile solution consisted of 74 piles with a structural capacity (ULS) of 163 kips. The pile design included a 118/7.5 Ductile Iron Pile section (118 mm outside diameter with 7.5 mm wall thickness) along with a #8 reinforcing bar centered in the pile and 3,000 psi grout. The piles were installed to depths ranging from 82 ft to 92 ft to bear on rock. Design at the site was verified with a full scale load test performed to over 230 kips.
A total of 39 vertical and 35 battered piles were installed by GeoSolv Design/Build in 12 shortened working days. Crews used installed the 5 meter long pile sections using a medium-sized CAT 315 excavator them to work from variable grades without the need for significant working grade modifications. The modular Ductile Iron Pile sections allowed for battered pile installation without obstruction due to existing adjacent retaining walls. The limited vibration generated with the system reduced potential issues with slope stability or impact on nearby rail activity.
This project in the Greater Toronto Area demonstrates many of the advantages of the Ductile Iron Pile system benefiting project teams trying to address challenging site conditions in a rapid and cost-effective manner. Find out more about the system and review other project examples at www.duroterra.com.