Effect of vibration on the critical state of dry granular soils

In order to investigate the effect of vibration on the critical state of dry granular soils, eighty samples of four different granular materials were tested at four normal stresses under different vibrational accelerations. The experiments were performed on a modified vibrational direct shear apparatus with vibrational loading in the horizontal (shear) direction. Strength loss versus vibration acceleration plots at different normal stresses, as well as the peak, residual and vibro-residual shear strength diagrams have been obtained for the four granular materials at different intensities of vibration. It has been determined that increasing the intensity of vibration reduces the friction angle of the granular materials. The effect of particle shape on the strength loss due to vibration has been observed as well as the effect of vibration on the normal stress.