The effect of parametric excitation on the prediction of railway induced vibrations in the built environment.

Ground-borne noise and vibration due to railway traffic is a problem oflarge societal and economical relevance. Railway induced vibrations aredue to several excitation mechanisms including wheel and rail unevenness, impact excitation due to rail joints and wheel flats, and parametric excitation due to spatial variation of the track stiffness.

Considerable progress has been made regarding the development of numerical prediction models. These models are indispensable for designing cost-effective vibration mitigation measures in response to the increased public sensitivity to noise and vibration. Although parametric excitation is commonly considered as an important excitation mechanism, it is generally disregarded in these models. Furthermore, recent studies show that the effectiveness of mitigation measures highly depends on the nature of the excitation mechanism. Accounting for parametric excitation in ground vibration predictions is therefore a key issue and the objective of the present PhD project. This is particularly challenging because assumptions onthe regularity of the track geometry, commonly made for enhanced computational efficiency, have to be abandoned. The novel methods developed inthis project will be used to study the effect of parametric excitation on the effectiveness of mitigation measures and the identification of track and subgrade properties from in situ tests.