High-speed train induced environmental vibrations: Experimental study on Isolation efficiency of recyclable in-filling materials for thin-walled hollow wave barrier

The most cost-effective method for reducing vibrations in structures affected by continuous railway traffic is the implementation of an open trench in the ground. However, using deep trenches without lateral support in residential areas is impractical from an engineering standpoint. Furthermore, the screening efficiency of solid wave barriers falls short of expectations. Full-scale field tests to assess the vibration isolation performance of open trenches are either limited or rely on stationary point sources generating periodic surface vibrations. The objective of this study is to investigate both free-field surface ground vibrations and the dynamic response of a specially constructed test building founded on alluvial soil close to high-speed railway traffic, considering both passively isolated and non-isolated conditions. The chosen testing location is Sakarya-Pamukova, a critical area along the Istanbul-Ankara High-Speed Train (HST) line in North-Western Türkiye. To address stability and near-surface groundwater issues, specially designed prefabricated panels with low impedance were placed in the trench. Additionally, the vibration screening performance of infill materials made from recyclable waste materials like wood shavings, Styrofoam, and expanded glass granules was evaluated for the trench-type wave barrier with thin aerated concrete walls. This evaluation considered both structural response and surface wave motions at the test site. In this full-scale experimental study under challenging geotechnical conditions, it has been demonstrated that significant attenuation effects (a reduction of up to 50%) near the high-speed railroad can be achieved at a depth equal to half the wavelength of the excavation. This was accomplished using a thin-walled wave barrier made of low-cost and environmentally friendly lightweight material. By employing various recyclable waste-filling materials, an additional benefit of up to 3 and 5 decibels was observed in vibration mitigation for structural and free field ground vibrations, respectively.