THE CONE FACTOR FOR A 30 DEGREES CONE

This paper considers the influence of a number of factors on the measured values for the cone factor as proposed by Hansbo. A series of fall cone and laboratory vane tests was conducted on soils of varying plasticity. The data obtained indicated that the cone factor was not constant over a wide range of penetrations. However, for the penetrations associated with the liquid limit a constant cone factor of 0.76 was indicated. Data are also presented to indicate an increase in cone factor with increasing plasticity and it is further suggested that additional work will be required to confirm this trend. Although the available data are biased towards low shear strength, they indicate a cone factor of 0.33 at an undrained vane shear strength of 100kPa. It may also be concluded that further testing will be required to investigate the influence of cone roughness on measured k values, and that the current criterion used in the liquid limit test for acceptable cone penetrations may not be stringent enough for the determination of cone factors. (A)