Abstract:
Deep Soil Mix (DSM) columns were used to stabilize an existing roadway and slope in a roadway at an existing DOE facility in Plaquemine, Louisiana. Starting in 2018, ground surface cracking and slope movements were observed in the roadway adjacent to Cavern Lake. Slope monitoring, vertical shape arrays, site observations, and back analyses confirmed the movements were the result of global instability, with back analyzed global factors of safety less than 1.0 for both shallow and deep-seated slip surfaces. The failure resulted in road closure, greatly limiting facility access. Several stabilization alternatives were considered to allow the roadway to remain in services without risk for further de-stabilization of the slope. Deep soil mix (DSM) columns were selected due to the low vibrations associated with the DSM process and high replacement ratio, which would both increase the global FS and provide added subgrade stability for the re-constructed roadway. This presentation will discuss the engineering considerations for the DSM ground improvement solution and discuss the construction process and observations, as well as the current roadway and slope condition six years after completion of the site work.