Keywords: railway infrastructure, numerical simulations, soil stabilisation, geotextiles, stiffness variation, transition zone.

For freight railways to gain competitiveness with respect to other transportation modes it is required to look at new solutions for freight transportation that are faster and less expensive over their entire life cycle. This can be obtained by new freight vehicles running at higher speeds and higher tonnages under controlled conditions over a more resilient infrastructure. The new traffic conditions impose higher dynamic loads on the infrastructure which need to be carefully analysed. In particular, for the track itself to maintain its geometry for the maximum length of time (under various traffic conditions), it is important that the substrate is in a homogeneous condition, and remains so as far as is reasonably practicable given other influences such as climatic effects (temperature, groundwater content, etc.). This study, described in this paper, focuses on the role of track substrate stiffness and structure in enabling the railway to effectively bear the higher dynamic loads from a new generation of freight vehicles. The impact of substrate stiffness variation on track geometry deterioration and other track defects is investigated with attention to specific freight train typology (namely flat bed wagon), to different loading conditions (e.g. from full to laden to tare) and speeds at "critical" track locations (e.g. transitions onto and off bridge abutments, etc.). Input data on track stiffness, support conditions and rail cross-section are used to conduct computational dynamic analysis to understand the effects of different rail cross-sections and different support conditions. By including in this investigation the effects of differential stiffness at critical locations, this will enable an optimisation of the substrate stiffness and of the ballast system by making use of ground treatment and of ground stabilisation techniques, such as the use of geogrids. The models will be validated from field measurements and will be used for the evaluation of ground stabilisation techniques (e.g. geotextiles) and the identification of methods to homogenise substrate stiffness in transition zones, thus helping to reduce track geometry degradation, contributing to a near zero maintenance target for the infrastructure.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £65 +P&P)