Monotonic and cyclic undrained shear behaviour of volcanic soil `Shirasu'

A series of undrained cyclic and monotonic triaxial tests has been performed on a volcanic soil `Shirasu' which has crushable particles. Testing was performed on loose and dense specimens and the results were compared with those of Toyoura sand. As a result, the undrained cyclic and monotonic shear behaviour of `Shirasu' is found to be greatly dependent on the confining pressure and its density. The undrained cyclic shear stress ratio to cause failure increases in loose specimen while it decreases in dense specimen with increasing confining pressure.