Development and performance of a shear vane at high revolution in boreholes

Abstract

The vane shear test is a traditional in situ method. From its origin, the standardized methodology of this test has been orientated to obtain the undrained shear strength S_u, of fine grained soils with low permeability. Considering the geotechnical need for characterizing fine sandy soils and/or fine grained soils with higher permeability, this article presents the development and implementation of a vane shear test adapted to reach angular velocities of around 100 rpm. This rotational velocity ensures an undrained behaviour on materials such as silty fine sands. Also, this test was developed to be implemented on drilling rigs in order to make vane tests at different depths. Results obtained in tailings are presented. In this article, the composition of the equipment developed - mechanical parts and data acquisition system- test methodology, initial test results and final comments are presented.