Analytical Approach to Describe Properties in Transition Zones Between Ballasted and Non-Ballasted Track

Abstract

Norway has for a long time used railways as a means of transport. This method of transportation been used to haul raw materials such as wood and ore. Trains have today become competitors to cars and other means of transportation as a way to commute. However, the tracks used when hauling heavy loads are still being used regardless if the train's goods are commuters or raw materials. Heavy freight trains have a relatively low velocity compared with high-speed trains and because of this, ballasted tracks often used in Norway. The increase in commercial use of train transport has lead to a train-velocity increase and as a result of that, development of non-ballasted tracks have therefore become more favorable. The non-ballasted tracks have a higher stiffness than the ballasted, consequently problems arises when the softer ballasted track transitions over to the stiffer non-ballasted track. Because of the difference in stiffness, will there be a point in the track where the stiffness abruptly changes from one stiffness to another. This will cause damages to the rail, track and train if not dealt with carefully.

The railway company Bane NOR have therefore published an interest in the topic of equalizing the stiffness in transition zones. Gaining a deeper understanding of what happens during a transition zone is important so that unnecessary track degradation can be prevented. However, because of the scarcity of information about this particular topic, this thesis could be beneficial to the community. Transition zones are usually designed based upon prior experiences, and the construction of the zones are commonly done by subcontractors. Bane NOR is therefore aspiring to acquire theoretical models that can describe the rail behaviour in transition zones.

This master's thesis covers the development of an analytical mathematical model that describes the rail's deflection in both ballasted and non-ballasted tracks. The model takes root in an older theory called "beams on elastic foundation" and the "moving force on a beam" problem. Beams on elastic foundation theory is often used in the railway industry to describe the deflection of rails. Furthermore, the numerical analysis software ANSYS, was utilized to generate an animation of the deflection of the rail beam.