The sleeve friction measurement, fs, is considered to be the least reliable of the three measurements in piezocone testing. It has been shown that the diameter of the friction sleeve in relation to the cone tip diameter has an effect on the sleeve friction measurements (fs). Testing standards (e.g. ASTM D 5778-12) allow a tolerance range such that the friction sleeve can be equal to, or up to 0.35 mm greater than the cone tip diameter. Cone penetrometers with larger friction sleeve diameters show higher fs measurements (Holtrigter, et al. 2014). The most accurate results are generally considered to be when the friction sleeve and cone tip are of the same diameter (Cabal and Robertson 2014). In this study, friction sleeves of different diameter have been used in side-by-side piezocone testing on two test sites in New Zealand to investigation the variation to sleeve friction measurements with sleeve diameter. By empirical correlation of these tests the equation to allow correction for this effect (Holtrigter et al. 2014) has been further developed.
This paper was originally presented at the Geotechnical and Geophysical Site Characterisation 5 conference and is reproduced here with permission of the Australian Geomechanics Society. For additional papers from this conference see http://australiangeomechanics.org/public-resources/downloads/#dlISC5 Proceedings