In the course of the research project FFG-projectnr. 840545 an experimental plant (a ballast trough with vertical inducted vibrations) is planned in order to determine the parameters of ballast bed (damping, stiffness) for vertical shear deformations (in dependence on amplitude and frequency of oscillation). This represents the basic data to describe the dynamic effects of the ballast bed on bridges (vertical shear deformations and vertical inertia forces in the track). With these parameters and analogy observations (this means without experiments with horizontal shear deformations of the ballast bed) the parameters of ballast bed in the dam area (for horizontal shear deformations of the ballast substructure due to longitudinal shift of the track) are determined.
The issue is that an approximation (whereby the degree of approximation is unknown) is on Hand because horizontal shear deformations are not possible to generate with the given experimental plant. In the course of the research project FFG-projectnr. 840545 dry ballast without preloaded ballast (to stimulate the load of a moving wheel-set) will be used. The issue in this case is that in reality the behaviour of the ballast bed (and therefore the effect on bridge swinging) is influenced by vertical load through the wheel-set and climatic boundary conditions. From this described issue a demand for systematic study of the parameters of ballast bed is given. In which vertical and horizontal shear deformations of the ballast bed with consideration of preload on the ballast bed and climatic boundary conditions are assured.