Influence of stiffening ballasted track bed overlying a masonry arch bridge using a polyurethane polymer material

A finite element analysis of a masonry arch railway bridge has been conducted to study the stabilizing effects on the bridge using polyurethane polymer reinforcement of part of the ballast. Ballast is a highly non-linear granular material and its behaviour is influenced by the formation and subgrade structure. The track support and its deterioration with time is dependent on a number of parameters. Arch structures were designed for lower vehicle loads than they are currently subjected to so this work is focused on finding an innovative way of extending the scope of a proven ballast strengthening technique (XiTRACK) to encompass arch bridges, allowing a better distribution of the loads from the trains and hence to reduce the pressure on the arch. This work will provide a technique for the stabilization of masonry bridges using polyurethanes in order to address specific problems associated with the bridge structure. This involves numerical modelling of the ballast structure, the arch fill and the response of an arch barrel to achieve the optimum use of the material. The work is still under development as the current analysis uses a linear elastic model of the bridge, due to calibration of the data readings taking from the actual bridge, however further work using non linear plasticity is underway.