Mitigation of train induced vibrations by wave impeding blocks: numerical prediction and experimental validation

In the frame of the Eurostars project "SOILVIBES", a mitigation measure based on wave impeding blocks (WIB) was proposed and designed for reducing the intensity of train-induced vibrations in an urban area. Using a 2.5D finite element-boundary element method, a numerical tool was implemented to determine the most efficient and realistic configuration of the wave impeding blocks. This numerical tool can also predict the efficiency of the proposed system before the installation. Results of the numerical modelling show that a heavier and wider system can provide a higher efficiency. Based on the results of the numerical modelling, two different systems were selected to be tested: (1) three rows of concrete blocks parallel to the railway (placed directly on the ground surface) and (2) three rows of concrete blocks over a resilient layer (the tuned mass absorber). To validate the numerical prediction model, the experimental measurements in both the small and the full-scale were performed. The small-scale test was done in a test bench in the laboratory with a geometric scale factor of 15. Furthermore, a full-scale test was also designed and performed in a site adjacent to a SNCF railway line in north eastern of France. Although, it was expected that the concrete block over a resilient layer would act as a tuned mass absorber and better control the ground vibration than the blocks without the resilient layer, the results of both experimental and numerical simulations show that the concrete blocks placed directly on the soil surface can provide a higher efficiency than the concrete blocks on the resilient layer. In addition, the results of experimental measurements (the small and the full-scale tests) reasonably confirm those predicted by the numerical modelling.