Volume 37, N. 3, Special Issue: In Situ Testing for Ground Characterization (Invited Editor: Roberto Q. Coutinho), September-December, 2014 | PDF(7 downloads)
Cone penetration in mixed or intermediate soils (soils containing mixtures of sand, silt and clay) is neither fully drained nor fully undrained at the standard cone penetration rate of 20 mm/s. Considerable research, mainly relying on centrifuge tests, has been undertaken to quantify the effects of penetration rate (and thus partial drainage) on cone resistance. In this paper, the effects of penetration rate on cone resistance in saturated clayey soils were investigated by performing field tests and miniature cone penetration tests in a calibration chamber. The field tests were performed at sites especially selected to span the range of drainage conditions from fully drained to fully undrained. The calibration chamber tests, using both conical and flat-tip penetrometers, were performed at different penetration rates in two specimens prepared by mixing kaolin clay and sand with different mixing ratios and one-dimensionally consolidateding the mixtures. A correlation between cone resistance and drainage conditions is established based on the cone penetration test results. The transitions from no drainage to partial drainage and from partial drainage to full drainage are defined as a function of penetration rate normalized with respect to the penetrometer diameter and the coefficient of consolidation.