Leamington, Ont. - Underwater Lateral Load Testing on Concrete Caissons
Ministry of Transportation of Ontario
Riggs Engineering was hired to develop an underwater lateral load testing program for testing the integrity of reinforced concrete caisson piles installed adjacent to a ferry dock in Leamington, Ontario.
As part of rehabilitation works to increase the depth in front of a dock, 914 mm diameter concrete caissons, spaced 2.5 m apart along the length of the dock, were drilled into bedrock in order to underpin the existing sheet pile wall and provide a deeper dredge grade for the local ferry. During the installation of caissons the contractor encountered ground conditions previously undetected.
The top of the caissons were underneath 6-8 m of water, thereby limiting the ability in using conventional pile integrity testing equipment.
In order to verify the integrity of the caissons, an underwater lateral load test was designed to monitor load-deformation behaviour to a sub millimeter scale using divers and an underwater Linear Variable Displacement Transducer (LVDT). The measured load-deformation curves were compared to theoretical pile movements computed via the p-y method using soil properties estimated from conventional and self boring pressure meter results.