ABSTRACT
Results from recent piezocone testing are compared with a statistical set of 22 prior CPTU soundings at the Opelika National Geotechnical Experimentation Site in Alabama. The site is underlain by residua comprised of fine sandy silts of the Appalachian Piedmont geologic province in the eastern USA. The cone resistance and sleeve friction from a 2016 CPTU compare well with the mean values from previous soundings while the porewater pressure readings are similar yet different because of a drop in the groundwater table from 2 m to 10 m over the period of study. Evaluations of the effective friction angle and yield stress from CPTU in residual soils are presented and compared with benchmark values obtained from laboratory triaxial and consolidation test results. Most interestingly, as the soil is intermediate with about 50-50 silt and sand, both undrained and drained penetration give more or less the same results.
