Stability of Low Embankments on Soft Clay. Part 1. Tests with Centrifuge Vane and Penetrometers on Clay Cakes in a Normal Gravity Field.
Final technical rept.,
CAMBRIDGE UNIV (ENGLAND) DEPT OF ENGINEERING
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Small vane and penetrometer devices have been developed to measured soil properties in centrifuge models during flight. Early models of these devices, and subsequent improved devices which allow separation of shaft friction from cone or vane resistance, are described, and results presented from tests on consolidated clay cakes in a normal gravity field. A small piezocone has also been developed. Vane results are shown to be strongly influenced by vane diameter, but not vane height, by elapsed time between insertion and rotation of the vane and by the rate of rotation. From these results a vane size of 18 mm diameter by 14 mm high is recommended with a rotation rate of 72min. A penetration rate of 5 mms is found to be suitable for a 10 mm diameter cone although in fact penetration rate was found to have little influence on the measured cone resistance. A consistent relationship could not be established between cone resistance and vane strength. The ratio of cone resistance to vane strength was found to increase with increasing overconsolidation ratio, but was also found to depend on various other factors such as vane and cone sizes and testing rates. The values also differed considerably between the two clays used, Gault clay and kaolin.
- Soil Mechanics