Target Store Slope Repair
At a commercial development in Raleigh, NC, the combination of heavy rains and an overly steepened fill slope resulted in a landslide during the winter months. The 65 ft high fill slope supported a parking and loading dock area for a large commercial super store.
The compacted fill slopes consisted of on-site residual silty sands and sandy silts from the Piedmont physiographic Province. These soils typically have long term effective friction angles on the order of 28 to 30 degrees. However, the compacted soil slopes were built at slope angles ranging from 26.5 degrees to as steep as 33.7 degrees. The resulting slides consisted of a series of shallow veneer compound slides which encroached on the parking area at the crest and the adjacent property and roadway at the toe.
Geopier Soil Reinforcements, MSE and Cantilever Post and Panel Walls proved to be the best solution. The initial repair schemes consisted of conventional methods of excavating a trench below the slide mass and backfilling with a toe buttress consisting of riprap and a gravity gabion wall. The planned depth of the excavation required staged construction, and/or shoring, and removal of a significant amount of soil. An alternative solution, consisting of Geopier technology reinforcing the slope failure plane, use of a gabion-faced MSE wall as a toe buttress and a low height H-pile and concrete lagging wall at the crest of the slope was proposed and accepted.