| The techniques for stabilizing existing levee embankments on soft foundations are investigated and analyzed. Slope flattening, constant height berms, sloped and stepped berms are the concepts used to analyze increases in slope stability. Soil classification and undrained shear strength parameters obtained from typical laboratory data techniques and CPT (cone penetration test) explorations are compared. Post-construction CPTs of a levee strengthening project using constant height berms were conducted to compare the foundation changes from pre-construction. Three specific modes of failure are introduced to examine the complete stability of the entire levee and foundation section. Constant height, sloped, and stepped berms are examined to determine which concepts would yield the minimum required factor of safety for all three modes of failure. Sloped and stepped berms, whereby the berm height decreases with increasing distance from the landside levee toe, are found to meet the minimum required factor of safety for all three modes of failure. |
