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Schlagworte
- Ground vibration (4)
- Finite element method (2)
- Railway track (2)
- Track-soil interaction (2)
- Amplitude-distance law (1)
- Blasting charge (1)
- Boundary element method (1)
- Building response (1)
- Combined finite-element boundary-element method (1)
- Components of excitation (1)
- Drop height (1)
- Dynamic loads (1)
- Excitation forces (1)
- Explosion (1)
- Field tests (1)
- Filter effect of the soil (1)
- Flexible car body (1)
- Flexible wheelset (1)
- Layered soil (1)
- Mass drop (1)
- Measurement campaigns (1)
- Mitigation (1)
- Monitoring (1)
- Railway induced vibration (1)
- Rigid vehicle model (1)
- Slab track (1)
- Target stiffness (1)
- Track and vehicle irregularities (1)
- Track damage (1)
- Track damage monitoring (1)
- Track damage quantification (1)
- Train passage (1)
- Train speed (1)
- Train-induced ground vibration (1)
- Under-sleeper pads (1)
- Vehicle-track-soil interaction (1)
- Wavenumber integrals (1)
- Wheelset accelerations (1)
Organisationseinheit der BAM
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This article deals with two topics of vehicle-track-soil interaction, the mitigation of railway induced ground vibration by soft track elements, and the identification of track damage. Theoretical results have been achieved by a combined finite-element boundary-element method (FEBEM). The theoretical results are confronted with measurements at four sites. Improved mitigation effects have been found for soft rail pads under heavy sleepers. The insertion loss, however, can be too optimistic if a strong vehicle track resonance occurs for the un-isolated reference track. Two measurement sites show this strong vehicle-track resonance at about 80 Hz, which has been approximated by using the results of a wide parameter study including the rail pad, ballast, and soil stiffness, as well as the ballast model and the soil layering. – The detection of slab track damage is mainly based on the differences of the receptance or compliance functions. Theoretical results have been confirmed by measurements at one site where a loss of contact between track plate and base layer was visible. Measurements at a second site with a hidden damage have been compared with the theoretical results of a loose sleeper. The differences between intact (or repaired) and damaged tracks are strong enough to encourage the further development of this method for the identification of track damages.
Three measurement campaigns of train-induced ground vibrations are evaluated for the vehicle-track-soil interaction. Ground vibrations, track vibrations and vehicle vibrations have been measured for train passages and impulse excitation and compared with theoretical results.
The soil and the track-soil system are calculated by wavenumber integrals. The influence of the vehicle is introduced by a substructure method. By comparing theory and measurement the different components of excitation force and ground vibration can be analysed, the quasi-static excitation, track-alignment errors, the out-of-roundness of wheels, the wheel and rail roughness, and moreover, scattered axle impulses and ineffective high-frequency parts of the wheelset accelerations and forces.
Ground vibrations near railway lines are generated by the forces that are acting between wheel and rail. It seems to be a straight forward assumption that the vehicle dynamics are important for the level and the frequencies of the excitation forces. Different vehicle dynamics phenomena are analysed for their role in the excitation of ground vibrations: rigid body modes of the bogies, elastic (bending) modes of the car body, and elastic modes of the wheelset. The theoretical analyses use rigid body models, simplified elastic models, and detailed elastic models. Some of these problems are vehicle–track interaction problems where 3D finite‑element boundary‑element models have been used for the track and soil. It is shown that the rigid or flexible vehicle modes are well in the frequency range of ground vibrations (4 to 100 Hz). They have an influence on the excitation force but the additional forces are rather small and can be neglected in ground vibration prediction. The theoretical results are checked by experimental results of a simultaneous measurement of vehicle,
track, and ground vibrations.