Field vane test

The vane shear test is an in-situ geotechnical testing methods used to estimate the undrained shear strength of fully saturated clays without disturbance. The test is relatively simple, quick,  and provides a cost-effective way of estimating the soil shear strength; therefore, it is widely used in geotechnical investigations. Under special condition, the vane shear test can be also carried out in the laboratory on undisturbed soil specimens; however, the use of the vane shear test in in-situ testing is much more common.

Description and procedure field vane test:

The test starts by pushing the vane and the rod vertically into the soft soil. The vane is then rotated at a slow rate of 6° to 12° per minute. The torque is measured at regular time intervals and the test continues until a maximum torque is reached and the vane rotates rapidly for several revolutions. At this time, the soil fails in shear on a cylindrical surface around the vane. The rotation is usually continued after shearing and the torque is measured to estimate the remolded shear strength.

The result of Field vane test are primarily consisted of the followings:

• Maximum Undrained Shear Strength (at each test depth);
• Remolded Shear Strength (at each test depth);
• Sensitivity (i.e. Maximum undrained strength / Remolded strength);

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Example results of field vane test: