Abstract
Under sleeper pads have been installed to reduce the vibration from sleepers to substructures. In recent years, the under sleeper pads molded by foam rubbers have been examined for applying them to the ballasted track. The elasticity of foam rubber materials can be easily changed by modifying the foaming ratio, and the thickness of under sleeper pads can be reduced. Because foam rubber deforms with compression of the porous cells in itself, the contact area between the under sleeper pad and the surface of the ballast is locally increased according to the roughness of the ballast. Thus, it is expected that the load and vibration to the ballast layer is absorbed and reduce the ballasted track settlement. In this paper, vibration and noise level near the track were measured in the presence and absence of under sleeper pads with foaming rubber. As a result, it was confirmed that the vibration level to the ground was reduced because of the installation of the under sleeper pad and noise level was similar even if the under sleeper pads were installed.
