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- 2012 (15) (entfernen)
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- Vortrag (10)
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- Ground vibration (3)
- Slab track (2)
- Excitation forces (1)
- Finite-element boudnary-element method (1)
- Floating slab track (1)
- Force transfer (1)
- High-speed trains (1)
- Layered soil (1)
- Measured railway vibrations (1)
- Mitigation (1)
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- Railway track (1)
- Track vibration (1)
- Track-soil interaction (1)
- Under sleeper pad (1)
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Eingeladener Vortrag
- nein (10)
The dynamics of slab tracks and floating slab tracks are analyzed by multibeam models for the track and by integration in the wave-number domain for the soil, which is modeled as a layered half-space. Frequency-dependent compliances and force transfers are calculated for a great variety of track and soil parameters. The distribution of the load and the displacements along the track is investigated as well as the wave propagation perpendicular to the track and the ground vibration amplitudes. The floating slab track has a dominating plate-mat resonance and a strong high-frequency reduction. A track-soil resonance can also be recognized for an unisolated slab track in the case of layered soils. Generally, there is a strong damping of the track by the soil. The reduction effect of the slab mat is mainly owing to the elimination of this strong damping. The continuous soil yields slightly different rules for the displacements and force densities than those of a Winkler support. The total force transfer from the rail to the soil is the best criterion to judge the effectiveness of a floating slab track in reducing the ground vibration at some distance from the railway line. The total force transfer is easier to calculate than the double Fourier integrals of the ground vibration amplitudes, namely in the far field, and it has the best correlation with the reduction of the ground vibration.
Vehicle, track and ground vibration as well as their interaction are considered in a combined finite-element boundary-element (FEBEM) approach. The layered soil is calculated in frequency wavenumber domain and the solution for fixed or moving point or track loads follow as wavenumber integrals. The soil results from the measurements and the detailed models are approximated by simple formula which are used for the prediction of train-induced ground vibration. The influence of the track and the soil on the train induced ground vibration is analysed by the detailed models. The ground vibrations strongly depend on the regular and random inhomogeneity of the soil. The regular layering of the soil yields a cut-on and resonance phenomenon while the random inhomogeneity yields a scattering of the axle impulses which proved to be important for high-speed trains. The attenuation with distance of the ground vibration due to the point-like excitations such as vibrator or hammer excitations and the train-track excitation are investigated and compared. All theoretical results are compared with measurements at conventional and high-speed railway lines.
Um die Erschütterungen infolge von Schienenverkehr zu reduzieren, werden elastische Elemente in den Eisenbahnfahrweg eingebaut: elastische Zwischenlagen zwischen Schiene und Schwelle, elastische Schwellensohlen zwischen Schwelle und Schotter und Unterschottermatten unterhalb des Schotters. Das elastische Element führt zu einer ausgeprägten Eigenfrequenz des Gesamtsystems bestehend aus Fahrzeug, Fahrweg und Untergrund. Die Wirkung der elastischen Elemente beruht darauf, dass die Frequenzen oberhalb dieser Eigenfrequenz abgemindert werden. Für die Ermittlung der Wirksamkeit der Minderungsmaßnahme werden das Gleis mit elastischem Element und das Gleis ohne elastisches Element berechnet. Beide Eisenbahnfahrwege werden mit der kombinierten Finite-Element- Randelement-Methode berechnet, wobei das Gleis einschließlich des Schotters mit der Finite-Element-Methode berechnet wird, der Gleisuntergrund hingegen mit der Randelementmethode. Für die erschütterungsmindernden Gleise erweist es sich als vorteilhaft, spezielle Gleisendelemente an den Seiten des FE-Modells anzufügen. Dadurch wird zusätzlich zur Unendlichkeit des Untergrundes auch die unendliche Länge des Gleises berücksichtigt. Für die Ermittlung der Minderungswirkung werden die frequenzabhängige Nachgiebigkeit des Gleise, die Kraftübertragung des Gleises, und die Fahrzeug-Fahrweg-Wechselwirkung berechnet. Schließlich werden die Kraftminderungen verschiedener Eisenbahnfahrwege dargestellt und der Einfluss der wesentlichen Parameter untersucht.