Application and evaluation of embankment construction specification for cohesive soil using the dynamic cone penetrometer
Charles T. Jahren
A series of research projects were conducted starting in 1997 to evaluate the Iowa Department of Transportation's construction practices and specifications after a series of large embankment failures. Iowa State University researchers developed alternative methods for construction and quality control of earthen embankment utilizing strength based soil measurements. A formal construction specification was later developed that incorporated the elements of the previous studies into a usable embankment construction specification. This research focuses on the application of that construction specification to a pilot project in high plasticity clay soils. This work is one of the few documented cases of applying a strength based earthwork quality control procedure for cohesive fill. The results of this study show that the requirements of this specification are suitable for construction in these types of soils. Furthermore, performance testing on completed embankment fill revealed that adequate levels of shear strength were attained. Observations at the project did reveal that one area of concern is the material property testing. New provisions are recommended to address these concerns.