Preliminary study on the similitude of physical modelling of ground improvement by vibro stone columns

The source mechanism of vibrator and the installation process of vibro stone columns play important role in revealing the improvement mechanism of stone column-improved ground. As it is difficult to observe the motion of vibrator and the installation process of vibro stone columns in engineering sites, it is more practical to reproduce such a complex problem and observe the vibration response by physical modelling. In this study, firstly the conical oscillation motion of the vibrator is simplified as in-plane oscillation, and the expression for the vibration-induced pressure on the surrounding soil is derived through the torque balance analysis. Then based on the Buckingham's π theorem, the scaling factor of vibration-induced pressure is obtained through the dimensional analysis, and it is found that the mass of the eccentric block, eccentricity, rotational angular velocity of the eccentric block and gravitational acceleration are the key factors. Finally the scaling factors of the vibration source parameters such as the maximum output mechanical power, excitation force and excitation acceleration generated by the vibrator are derived through the equation analysis, and then the scaling law for the model vibrator under 1g or hypergravity (Ng) environments is preliminarily proposed. This study provides the preliminary scaling law for the physical modelling of ground improvement by the vibro stone columns.