Effect of the scatter between CPTU measured parameters in soil classification

Abstract

Using piezocones from different manufacturers may yield different results even if the equipment complies with international standards. This causes problems when soil investigation contractors, using different cones, operate in the same area, and especially on the same project. Studies done in soft clay, sand, silt, and quick clays from different Norwegian sites show that repeatability for the cone resistance measurements and penetration pore pressure is good and that it has improved from one cone type to another. However, the scatter in the measured sleeve friction, and hence the friction ratio, is still very significant. Here, an attempt is made to qualitatively describe the impact of the scatter in the soil classification based on CPTU parameters. The most common soil classification charts are used to illustrate this scatter.