The proposed MSE approaches were underlain by a 10 to 18 foot layer of medium dense sand. Below this was a 3 to 8 foot thick deposit of very soft organics and clays, above a dense sand layer. At the upper walls, the subsurface profile included an additional 14 to 26 feet of compacted highway embankment at the surface. Due to the compressibility of the organic deposit, excessive long-term settlement was predicted for the new bridge approaches.
Several ground improvement options were considered for the project, including auger cast-in-place piles, vibro concrete columns and aggregate piers. CMC Rigid Inclusions were selected as the most appropriate solution to improve the soil prior to MSE wall construction based on Menard’s experience with similar projects, construction schedule, and cost-effectiveness.
More than 1,200 CMC Rigid Inclusions were installed to depths ranging from 13 to 48 feet. This ground improvement solution reduced post-construction settlement to acceptable levels, improved the bearing capacity and global stability of the tall walls, and supported four MSE walls.
The MSE retaining walls were designed by The Reinforced Earth Company, an affiliate company of Menard and member of the Soletanche Freyssinet Group.