Mitigation of railway induced vibrations by using subgrade stiffening and wave impeding blocks

Toward, Martin, Jiang, Jian, Dijckmans, A., Coulier, P., Thompson, David, Degrande, G., Lombaert, G. and Hussein, Mohammed farouk mohammed FM (2014) Mitigation of railway induced vibrations by using subgrade stiffening and wave impeding blocks. Cunha, A. and Caetano, E. (eds.) In 9th International Conference on Structural Dynamics (EURODYN 2014). Universidade do Porto. p. 783 .

Abstract

On sites with soft ground, stiffening of the subgrade beneath railway track has been associated with a reduction inground-borne vibration. However, the mechanisms behind this reduction are not well understood. Here, the effects are examinedin the context of two alternative approaches: (i) subgrade stiffening, where the soil directly under the track is stiffened, and (ii)wave impeding blocks, where stiff inclusions are positioned at some depth under the track. The efficacy of the measures areconsidered for three different ground types in a parametric study carried out using a 2.5D coupled finite-element / boundaryelement methodology. With a 6 m wide, 0.5 m high concrete block directly under the track, the vibration between 8 and 50 Hzwas reduced at the two sites with soft soil by between 2 and 8 dB at distances up to 32 m. In contrast, at the stiffer soil site, thereductions in vibration from this block were more modest (< 3dB). Similar reductions were observed for the three sites when theblock was positioned 0.9 m below the surface (i.e. as a wave impeding block), suggesting that, as with stiffening directly underthe track, the reduction in vibration was primarily due to the increase of the effective stiffness of the soil beneath the track ratherthan the effective creation of a new soil layer and resultant cut-on frequency. Jet grouting, whereby the ground is improved bycutting it with a high pressure water jet and then replaced with a cement grout, was considered as an alternative to concrete.Although it proved to be less effective due to the comparatively low stiffness, it may still be considered as a practical measurefor existing track on soft soil sites.

This record has no associated files available for download.

Contributors

Author: Martin Toward

Author: David Thompson

Download statistics