Abstract:
Construction of a replacement bridge spanning the Chain of Rocks Canal north of St. Louis, Missouri was recently completed. The new bridge foundations primarily include drilled shafts although construction difficulties at one location necessitated the use of a pile group to mitigate the construction issue. Accordingly, a post-award design was conducted to replace an abandoned drilled shaft with a group of driven piles. Careful consideration regarding the foundation response was necessary because of the seismic demand, and the axial and lateral stiffness of the pile group had to match the baseline design to avoid changes in the substructure design. Therefore, a rigorous analysis was performed to determine an appropriate driven pile foundation configuration and section. The reliability of the design was enhanced and verified by high-strain dynamic testing on 100 percent of the driven piles in the group. This presentation will briefly describe the construction issue related to the baseline drilled shaft installation and will then discuss the successful mitigation using a group of driven piles.