Design and in field validation of a modular metamaterial for mitigation of railway induced vibrations

Metamaterials are artificial structures exhibiting wave control properties that can be exploited in civil engineering applications. Among them, locally resonant metamaterials are able to control and manipulate wave propagation at wavelengths several times larger than the unit cell size, and can therefore be useful for low-frequency vibration suppression. This paper presents the design, installation and validation of a 0.4 m thick metamaterial-based panel for mitigation of railway-induced vibrations. The barrier comprises a cubic locally resonating unit made of four concrete pyramids connected together by external slender steel rebars. The unit cell is characterized from the dynamic point of view both numerically and experimentally, and a full-scale field test is then performed on the barrier at the railway station in Elze (Germany). This test validates the effectiveness of the metamaterial-based panel in providing a low-frequency mitigation of 10 dB at the resonance frequency around 30 Hz, in good agreement with the numerical and laboratory tests.