ABSTRACT
The paper proposes a simple and rapid test to measure in situ the drained shear strength of clay stones. The technique derives from the shear vane technique commonly used in soil mechanics. The tool is similar to the traditional shear vane, but modified in such a way to let it usables in harder materials. The proposed test doesn’t give the sharp value of share strength but, nevertheless, gives its order of magnitude from which the friction angle of the rock mass can be derived. Therefore it can be used in many practical problems involving claystone to avoid forming a doubtful estimate of this parameter of the rock mass.
