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- Train passage (4)
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- Slab track (3)
- Axle impulses (2)
- Axle sequence (2)
- Ground vibration (2)
- Irregular soil (2)
- Static axle loads (2)
- Train-induced ground vibration (2)
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- Finite-element boundary-element method (1)
- Geometric vehicle and track irregularities (1)
- Irregular ballast (1)
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- Layered soils (1)
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- Modalanalyse (1)
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- Pile bending stiffness (1)
- Pile foundation (1)
- Quasi-static response; (1)
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- Railway (1)
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- Random dynamics and vibrations (1)
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- Resonance (1)
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- Scattering (1)
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- Track displacements (1)
- Track filter (1)
- Track filtering (1)
- Track-soil interaction (1)
- Train-induced vibration (1)
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- Tunnel-to-surface reduction (1)
- Vehicle-track interaction (1)
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- Wheelset (1)
- Wind energy tower (1)
- layered soil (1)
Organisationseinheit der BAM
- 7.2 Ingenieurbau (13) (entfernen)
A combined finite-element boundary-element method for the dynamic interaction of the soil with flexible structures such as single piles or complete wind energy towers has been developed. Flexible piles in different soils are analysed in frequency domain. The different parameters such as the stiffness of the soil, the bending stiffness and the radius of the hollow pile are analysed for their influence on the complex compliances. The results have been determined as specific power laws which are different for the different load cases (horizontal, rocking, coupling) and for the different soil models (Winkler, continuum with constant, root-parabolic and proportional-linear stiffness variation). The strongest influence of the soil stiffness can be found for the homogeneous soil and the horizontal component. Winkler soils have a weaker influence than the corresponding continuous soils. An offshore wind energy tower has been modeled and calculated for wind and wave loads.
The train passages over intact or damaged slab tracks on different soils have been calculated by the finite-element boundary-element or the wavenumber-domain method. The influence of track and soil parameters on the distribution of the track displacements and the soil forces has been analysed. The measured and calculated displacement time histories of train passages could be used to identify track damages such as lose sleepers or a lose track plate. The time histories and spectra of the soil forces can explain the measured ground vibration reduction of slab tracks. The calculated displacement and force distributions of slab tracks on continuous soils do not fulfil the Winkler hypothesis and Winkler models should not be used for track analysis.
The passage of the train is dominated by the impulses of the static axle loads. The response of the regular homogeneous and irregular soils has been calculated by the finite-element method in frequency domain. The superposition of the impulse responses yields the quasi-static component of the ground vibration which is restricted to very low frequencies and to the close near-field of the track. In case of an irregular soil or ballast of which the stiffness varies randomly in space, a mid-frequency ground vibration component is generated by the scattering of the axle impulses. Measurements will be shown which prove the existence of the mid-frequency ground vibration component and the unique explanation by the scattered axle impulses: many international measurements with a raised mid-frequency component, axle-box measurements with a too low mid-frequency dynamic load, amplitude-speed dependencies which are incompatible with irregularity-induced dynamic loads, and ground vibration reductions due to stiff track elements.