Cone penetrations tests were performed on the silty clays of Kentucky, U.S.A., using a boring rig to push the Dutch, friction sleeve, cone penetrometer. Thin-walled tube samples were taken from nearby boreholes. For the first four sites, unconfined compression tests and unconsolidated-undrained triaxial test were performed on the samples. For the last four sites, consolidated-undrained triaxial tests were performed on the samples. A procedure for estimating in situ shear strength from triaxial test stress paths was developed.

Small rock fragments in these residual soils caused erratic cone resistance at many locations. As a result, the friction sleeve resistance provided the best correlation with in situ shear strength. In situ shear strength was found to be approximately 80 percent of the friction sleeve resistance, which confirms the findings of others.

Report Date


Report Number

No. 394

Digital Object Identifier



Prepared for presentation to European Symposium on Penetration Testing, Stockholm, June 5-7, 1974.