SR15 Bridge over Dunns Creek
Putnam County, Florida
The project consisted of two twenty-two foot high approach embankments for a new bridge in Putnam County.
The geotechnical investigation found an eighteen foot thick layer of highly organic soils immediately beneath the ground surface. Under the proposed loading of the embankments, the organic soils would significantly consolidate causing damage to the proposed MSE embankment. De-mucking of the organic soils would not be feasible due to the high ground water table and proximity of the existing roadway.
Earth Tech Solution
Earth Tech installed Rigid Inclusions (RI’s) to transfer the load of the embankment through the soft organic soils and on to a more competent strata at depth. The RI’s were installed on a grid to depths up to forty five feet below grade. An engineered Load Transfer Platform (LTP) was constructed to transfer the embankment loads to the RI’s. The LTP was installed by the roadway contractor and consisted of layers of high friction angle backfill and geogrid. Multiple rapid load tests were performed on individual RI elements throughout the project to verify RI capacity.