Abstract
The transportation industry has rapidly evolved in recent decades, with high-speed railways (HSR) having substantially contributed to fulfilling the growing transportation needs of the global population. It is often referred to as the transport mode of the future since it provides four key attributes to consumers: safety, speed, capacity, and sustainability. Although HSR lines offer numerous benefits, increased ground vibrations and noise from faster train speeds and heavier axle loads have become a challenging railway operation issue. These ground-borne railway vibrations adversely affect the structural performance of the railway infrastructure, the vibration-sensitivity of buildings near the track, and the productivity and comfort of the residents in the buildings close to the railway tracks. The vibration mitigation strategies for railway tracks align with similar sources of cyclic dynamic loads since elastic wave propagation in soils is mostly analogous. The generation, propagation, and mitigation of ground vibrations highly depend on the embankment soil properties, subsurface conditions, and train characteristics (operational speed and axle load). Broadly, ground-borne vibrations from railways can be reduced by implementing control measures at the source or receptor, or by impeding the transmission path using wave barriers. More often, damping material in-filled trenches positioned at varied distances from the railway embankment (along the track) is used to attenuate vibrations due to their low cost and relatively high performance. It performs as a discontinuity in the path of the surface waves, causing them to reflect, refract, damp and then propagate an attenuated wave. This paper reviews the utilization of Expanded Polystyrene (EPS) geofoam as an in-fill material for vibration mitigation trenches, specifically for attenuation of high-speed train-induced ground vibrations. EPS geofoam infilled wave barrier trenches with higher depth, higher width, and placement close to the track exhibit maximum vibration attenuation efficiencies, up to 60–70%. Using lower-density EPS geofoam for in-filling the trench also delivers a higher vibration attenuation efficiency. Moreover, deploying an EPS geofoam layer at the slope of railway formations is found to be yet another effective method for mitigating ground-borne railway vibrations. Incorporating a hybrid combination of EPS geofoam in-filled trenches and EPS geofoam blocks at the slope of the railway formations exhibits a substantially high potential for attenuation of railway vibrations, irrespective of the underlying embankment soil. Investigating mitigation strategies using different EPS geofoam layouts reveals that significant vibration reduction can be achieved using EPS geofoam in-filled trenches as passive vibration wave barriers next to the railway tracks.
