The field vane shear test is a moderately rapid and economical in-situ method for determining the peak and remolded undrained shear strength of clayey soils. The test gives quite successful results in soft to moderately stiff clays and also in sensitive clays.
The test involves pushing a four-bladed vane into a clay stratum and slowly rotating. During rotating, the resisting torque is measuring. The undrained shear strength is defined from the measured peak resisting torque before the failure of soil. The test is performed with a regular intervals according to the ASTM D2573-01.