A numerical study on isolation performance of wave barriers

Highway and railway traffic, construction operations and machine foundations may cause undesired vibrations in their immediate vicinity. The number of studies concerning isolation of these vibrations have increased in recent years. Wave barriers such as open trench, in-filled trench, diaphragm wall and sheetpile are commonly used to reduce the effects of the vibrations. The experimental and numerical studies in the literature showed that open trenches exhibited the best screening efficiency. Therefore, parameters affecting the isolation performance of open trench were examined in the present study. First, a finite element model was created by using Plaxis software, then validated by the results of a previous experimental study. The validated model was used to investigate the influence of surrounding soil conditions on isolation efficiency of open trenches. The effect of soil layering, thicknesses and shear wave velocities of the soil layers was studied by means of parametric numerical analyses. The vibrations having frequencies in the range of 20 Hz and 80 Hz were generated by a sinusoidal loading. Peak ground accelerations were recorded at different observation points in the absence and the existence of 3 m deep open trench. Isolation performance of open trench was quantitatively obtained for different test configurations. The best isolation was achieved in a region close to the trench. The analyses showed that soil layering conditions had of great importance. As the thickness of the top most layer increases, the effect of soil layering becomes less important. The ratio between shear wave velocities of soil layers along with the excitation frequency designate the attenuation behavior of the vibrations. The isolation performance of the open trench increased with increasing vibration frequency. The findings of the present study were compared with those of reported in the literature and it was seen that they were consisted with the findings of the other numerical studies.