Small Cone Penetrometer Tests and Piezocone Tests in Laboratory Consolidated Clays

Abstract

Abstract Small vane, 10-mm-diameter cone penetrometer and 12.7-mm-diameter piezocone devices have been developed to measure soil properties in centrifuge models during flight. This paper presents tests with these devices on kaolin and Gault clay in a normal gravity field. Empirical cone factors were shown to increase with increasing overconsolidation ratio but were found to depend on other factors such as cone size and testing rates. The values also differed considerably between the two clays used. Tests with the small piezocone have shown that the ratio of pore pressure to point resistance decreases slightly with the overconsolidation ratio, but not enough for this ratio be used as a method for determining overconsolidation ratio (OCR). As shown by other workers, pore pressures acting around the tip influence measured tip resistance and should be taken into account when interpreting cone resistances in clays. Dissipation tests with the piezocone have yielded values of coefficient of consolidation agreeing very well with those from swelling tests on clay cakes.