PROPAGATION CHARACTERISTICS OF SURFACE AND IN-DEPTH VIBRATIONS IN SAND GROUNDS: A COMPARATIVE ANALYSIS

Abstract

This paper aims to investigate the propagation characteristics of blast-induced ground vibrations in loose dry sand under surface and underground vibration conditions by monitoring the particle velocities and dominant frequencies of artificially generated ground vibrations. For this purpose, a ball drop apparatus was used to generate surface and underground vibrations at different depths. The free fall of the ball induced ground vibrations by impact. A total of 60 laboratory-scale ground vibration monitoring tests were performed on 4 physical models placed in a tank designed for this study. The vibrations were monitored on the surface of the sand filling the tank. The obtained results demonstrated that surface vibrations resulted in higher particle velocities than those generated by underground vibrations and that particle velocities measured on the ground surface decreased as the depth of the underground vibration source increased. The frequency analysis emphasized that only low frequencies (<40 Hz) were generated by surface ground vibration monitoring tests whereas 86.67% of those induced by underground vibration monitoring tests were high frequencies (>40 Hz). It was also determined that increasing the depth of the vibration source resulted in decreasing the dominant frequency range within the range of high frequencies (>40 Hz).