Ultrasonic Modelling of Open Trenches Used as Seismic Barriers Against Traffic-induced Ground Vibrations

Various types of seismic barriers are used in practice to protect buildings from traffic-induced ground vibrations, mainly from propagating Rayleigh surface waves. One of the widely used types of seismic barriers are open trenches. Experimental investigations of real size trenches at frequencies typical for traffic-induced ground vibrations, i.e. at 10-100 Hz, are costly and time consuming. In the present work, an alternative and much less expensive approach is proposed - a reduced-scale experimental modelling using ultrasonic Rayleigh wave propagation over very small-scale replicas of real trenches. Experimental investigations of propagation of Rayleigh wave pulses with the central frequency of 1 MHz, which corresponds to the value of scaling factor of about 1:1000, have been carried out for a single trench and for periodic combinations of trenches. The results of the measurements of transmission and reflection coefficients of Rayleigh waves for different incident angles show that, for typical values of the parameters used in the experiments, periodic combinations of trenches represent efficient seismic barriers against traffic-induced ground vibrations.