Evaluating Undrained Shear Strength Using the Vane Shear Apparatus

This paper discusses the derivation of soil strength from the vane shear test, examining factors such as rotation rate and waiting time that may influence the observed result. In addition, several different vane geometries (differing height/diameter ratios) have been tested to examine the effect of aspect ratio on the observed vane shear strength. Results from vane shear tests are compared with those obtained from other in situ tests, in particular T-bar penetration tests. A new form of 'helical' vane test Is discussed, In which the standard vane apparatus is continuously rotated during penetration into the soil sample, resulting in a complete profile of soil strength. In the discussion, profiles of soil strength determined with varying penetration and rotation rate are compared with strength measurements obtained from more traditional in situ test methods.