A study was performed to determine the causes of differential subsidence of a hydraulically constructed sand embankment in a fresh water swamp. Among other test methods, an electric cone penetration test (ECPT) was used to determine the cause(s) for embankment, and thus pavement, distress. Because very little historical design and construction information was available to the authors for analysis, the approach used was of a forensic nature rather than that of a well-defined research study. The electronic cone penetrometer, in combination with other tests, proved to be an invaluable tool in determining the condition of the sand embankment. Consolidation test results and embankment and subgrade profiles obtained by ECPT and borings eliminated the possibility of continuing settlement of subgrade soils. The problem is within the hydraulically placed sand fill. It was determined that the sand embankment when hydraulically placed was not sufficiently densified and that in later years the top 6 ft of the embankment, which is above the water table, experienced various degrees of densification under traffic loadings. Remedial options were studied and recommendations were made for field evaluations of these methods.
Abstract