CPTU results at a silt test site in Norway: effect of cone penetrometer type

Five different cone penetrometers from different manufacturers have been used in comparative testing program at the Norwegian GeoTest site (NGTS) on silt in Halden, Norway. The influence of cone type on the standard CPTU parameters is quantified. The corrected cone resistance shows approximately the same level of scatter as the penetration pore pressure, but far less scatter compared to the sleeve friction. Most of the tests show good repeatability within each series of tests. For the derived parameters of normalized friction ratio (Fr) and pore pressure parameter (Bq), the scatter is seen to be larger than the measured parameters which is expected from combining several parameters with scatter. The pore pressure parameter shows less scatter than the normalized friction ratio. An attempt has been made to understand the reasons for the large variations on the friction measurements and recommendations for future CPTU testing on silt are given.