Underwater Lateral Load Testing on Concrete Caissons:
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.