Stabilization of a Failing Slope with Deep Soil Mix (DSM) Column Ground Improvement-PPT Presentation

PPT Presentation

Pdf Summary

In 2020, a roadway near the Bayou Choctaw Strategic Petroleum Reserve site in Plaquemine, Louisiana, developed cracking on soft, organic clay and silty clay, with sand at the base of the proposed treatment area. The project’s goal was to improve global slope stability.<br /><br />The site lies above a deep salt dome. Cavern #7, drilled in 1942, was located about 134 meters below grade and later collapsed in 1954. The presentation reviews subsurface conditions and 2019 survey data as context for the roadway instability.<br /><br />Several possible fixes were considered. Lowering the road or building a riprap berm was impractical because the roadway and underground utilities had to remain in place. A sheet-pile wall would require marine equipment, while vibratory installation risked liquefying silt or weakening saturated fine-grained soils; the wall would also be costly because of the large unbalanced load.<br /><br />Deep soil mixing (DSM) was selected to improve the factor of safety and directly support the roadway using land-based equipment. The presentation describes large-diameter, single-auger wet-method mixing and discusses bench-scale testing versus field performance.<br /><br />After construction, the client reported a slope-failure crack in July 2021, prompting site visits. The supplied material does not describe the findings of those visits or the project’s final performance.

Keywords

Bayou Choctaw

Strategic Petroleum Reserve

Plaquemine Louisiana

roadway cracking

slope stability

salt dome

deep soil mixing

wet-method mixing

organic clay

sheet-pile wall