Small vane and penetrometer devices have been developed to measure soil properties in models during centrifuge operation. To aid the interpretation of vane data from centrifuge models a series of tests was conducted in cakes of kaolin clay in a normal gravity field. In the experimental program the effects of disturbance during insertion, delay between insertion and rotation, rate of rotation and geometry of vane blades were investigated. The results were used to devise a scientific method of operation of the vane apparatus. Subsequent tests were all performed with a vane size of 18 mm diameter by 14 mm high. Penetrometer tests were conducted in cakes of kaolin and Gault clays. Vane shear strengths were used to calibrate the apparatus. The ratio of cone resistance to vane strength was found to increase with increasing over-consolidation ratio. The values also differed considerably between the two clays. Thus, while the penetrometer has the advantage of providing a continuous profile of resistance with depth, some care is required in converting this measurement into undrained shear strength.

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.

Correct assessment of soil properties in centrifuge tests require these to be measured during flight, and small vane and penetrometer devices have been developed with this purpose. The vane is fixed in position, but the penetrometer can traverse the length of the model, allowing tests to be made at different positions. A program of tests has been conducted in the centrifuge at 100g investigating the use of these methods in consolidated beds of clay. Clay beds consist of an overconsolidated layer with a top stiffer layer overlaying a normally consolidated layer. Curves of point resistance with depth are similar in shape to curves of vane strength with depth, and the stiffer layer obtained as a result of the stress history is indicated in both tests. However measured point resistances are lower than expected, which is attributed to water pressure effects around the cone tip.