ABSTRACT

There is a variety of methods which can be adjusted to the nature of the problem under study. Older methods are based on Boussinesq's analysis (multi-layer system with elastic behaviour) or consider the track system as a uni-directional problem. More modern methods use fmite element analysis, which permits to take into account the real geometry and the real stress-strain relationship. For some problems, boundary element methods may also be used. The complicated problems occurring in contact surfaces (rail-sleeper, sleeperballast, etc.) may be approached by unilateral contact theories, which, however, until now have failed to give accurate numerical results.