Rate of Shear Effects on Vane Shear Strength

Abstract

A series of laboratory vane shear tests was performed on sedimented samples of kaolinite and slaked Pierre shale to determine the effects of shear rate and vane dimensions on measured strength. Results of the tests were expressed in terms of shear strength on a vertical plane and were plotted versus average shear rate. For kaolinite samples vane shear strength decreased as shear rate increased because of partial drainage occurring at slower shear rates. However, for the highly plastic Pierre shale vane, shear strength increased as shear rate increased because of undrained creep occurring at slower rates of shear. Test results for kaolinite and Pierre shale are compared to published information from other studies.