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#### Sprache

- Englisch (37)
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#### Schlagworte

- Ground vibration (8)
- Layered soil (4)
- Railway track (4)
- Track-soil interaction (4)
- Vehicle-track interaction (4)
- Force transfer (3)
- Field tests (2)
- Finite-element boundary-element method (2)
- Railway (2)
- Rayleigh wave (2)
- Slab track (2)
- Track vibration (2)
- Wave propagation (2)
- Wavenumber integrals (2)
- Acoplamiento Método de los Elementos de Contorno-Método de los Elementos Finitos (1)
- Amplitude-distance law (1)
- Axle box measurements (1)
- Axle-load spectra (1)
- Ballast mat (1)
- Base isolation (1)
- Beam dynamics (1)
- Beam-soil interaction (1)
- Bending waves (1)
- Blasting charge (1)
- Boundary Element Method-Finite Element Method coupling (1)
- Boundary element method (1)
- Continuously inhomogeneous soils (1)
- Drop height (1)
- Dynamic pile and pile group stiffness (1)
- Dynamic soil-structure interaction (1)
- Elastic length (1)
- Elastic track elements (1)
- Emission (1)
- Environmental vibrations (1)
- Excitation forces (1)
- Experimental verification (1)
- Explosion (1)
- Filter effect of the soil (1)
- Finite element method (1)
- Finite-element method (1)
- Flexible plate (1)
- Floating slab track (1)
- Foundations (1)
- Frequency-wavenumber method (1)
- Geometric trackbed irregularities (1)
- High-speed trains (1)
- Insertion loss (1)
- Interacción dinámica suelo-estructura (1)
- Interaction (1)
- Interior load (1)
- Irregularities (1)
- Irrégularités et forces roue-rail (1)
- Kinematic and inertial soil-pile-building (1)
- Layered soils (1)
- Mass drop (1)
- Material damping (1)
- Measured railway vibrations (1)
- Measurements (1)
- Mitigation (1)
- Monitoring (1)
- Moving load (1)
- Multi-beam model (1)
- Multi-beam-on-support model (1)
- Ondes du sol multicouche (1)
- Parametric excitation (1)
- Pile bending stiffness (1)
- Pile foundation (1)
- Plate-soil interaction (1)
- Prediction (1)
- Predictions (1)
- Rail pad (1)
- Rail roughness (1)
- Railway forces (1)
- Railway measurement campaign (1)
- Railway track vibration (1)
- Reduction (1)
- Resonance (1)
- Resonancia en edificaciones (1)
- Resonant response (1)
- Scattering damping (1)
- Sleeper pad (1)
- Soil stiffness (1)
- Soil transfer function (1)
- Soil-building interaction (1)
- Stiffness (1)
- Target stiffness (1)
- Track (1)
- Track alignment (1)
- Track damage (1)
- Track deformation (1)
- Track dynamic (1)
- Track-soil and vehicle-track resonances (1)
- Train induced ground vibration (1)
- Train passage (1)
- Train speed (1)
- Varying track stiffness (1)
- Vibration (1)
- Vibration isolation (1)
- Vibration reduction (1)
- Wave attenuation (1)
- Wave excitation (1)
- Wavenumber method (1)
- Wheel out-of-roundness (1)
- Wheel-rail irregularities and forces (1)
- Wind energy tower (1)

#### Organisationseinheit der BAM

- 7 Bauwerkssicherheit (18)
- 7.2 Ingenieurbau (18)

The attenuation of technically induced surface waves is studied theoretically and experimentally. In this paper, nineteen measurements of ground vibrations induced by eight different technical sources including road and rail traffic, vibratory and impulsive construction work or pile driving, explosions, hammer impulses and mass drops are described, and it is shown that the technically induced ground vibrations exhibit a power-law attenuation ν ~ r -q where the exponents q are in the range of 0.5 to 2.0 and depend on the source types. Comparisons performed demonstrate that the measured exponents are considerably higher than theoretically expected. Some potential effects on ground vibration attenuation are theoretically analyzed. The most important effect is due to the material or scattering damping. Each frequency component is attenuated exponentially as exp(-kr), but for a broad-band excitation, the sum of the exponential laws also yields a power law but with a high exponent. Additional effects are discussed, for example the dispersion of the Rayleigh wave due to soil layering, which yields an additional exponent of 0.5 in cases of impulsive loading.

Construction work, such as pile driving and soil compaction, or road and railway traffic excite nearby buildings, and the perceptible or audible vibration can be a nuisance for nearby inhabitants. A simplified building model has been created for these situations, which includes the effects of soil-structure interaction, the low-frequency amplification along the height of the building as well as the high-frequency reduction and the floor resonances. The model consists of one wall for all supporting structures (walls and columns) and one floor for each storey. The effect of different floor resonance frequencies is included in a stochastic procedure. The soil is modelled by a spring and a viscous damper, and the free-field amplitudes of the soil are applied under this soil element.
The model can be calculated by transfer matrices or in a continuous wave-type version where an analytical solution can be evaluated numerically. The building response in the high-frequency (acoustic) region is calculated as mean values over wider frequency bands. The approach to an infinite building model can be found for these high frequencies and the corresponding soil-structure transfer can be described by the ratio of impedances at foundation level.
The rules for choosing the parameters to obtain realistic results are derived from complex calculations for example, for the stiffness and damping of building foundations and many measurements as for the damping of floor resonances. The influences on the floor resonance from the soil (damping) and the supporting structure (detuning) are important. Some more effects will be discussed by the simplified and detailed models and by measurements to establish a good understanding of ground-induced building vibrations.

Ground vibrations due to different technical sources are analysed in theory and experiment for the dispersion of Rayleigh waves and the admittance spectra. Both tasks are theoretically based on the same concept: The admittance function in frequencywavenumber domain yields the dispersion as its maxima, and the admittance function in space domain is obtained by integrating it over the wavenumbers. On the experimental side, many signal processing methods have been applied to many sites and have been developed by the authors in the last 35 years, i.e., time-domain methods, including the cross-correlation method, and frequency-domain methods such as the spectral analysis of surface waves with two or multiple sensors, the wavenumber-transform method, and the spatial autocorrelation method. All methods are presented by their basic formula and by at least one example site. Different sensor arrays and deterministic and stochastic sources have been tested for the spatial autocorrelation method and the wavenumber-transform method at several sites. In addition, all frequency-domain methods are presented for a specific layered site comparing their quality. The evaluated dispersion curves are very similar, but a somewhat higher frequency range has been found for the fastest method, i.e., the multi-sensor spectral-analysis-of-surface-waves method. The theoretical solutions have been used for the inversion of the measured dispersion to the soil profile of the specific layered soil. The theoretical soil model has subsequently been used to predict the ground vibration spectra of hammer and railway excitation that exhibit a good agreement with the corresponding measurements. Thus, the contribution shows the benefit of active and passive seismic methods for the prediction of railway vibration, including a new version of the spatial autocorrelation method for technical vibrations. On the other hand, technical and namely railway vibrations are considered a seismic source for the exploration of near surface soils.

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.

Ballast mats are an efficient measure to reduce the vibrations near railway lines. The vehicle-track system gets a low eigenfrequency due to the insertion of an elastic ballast mat under the ballast. For frequencies higher than this low vehicle-track eigenfrequency, the forces, which are generating the vibration of the soil, are considerably reduced. In this contribution, a combined finite-element boundary-matrix method is used to calculate a number of completely three-dimensional track models with and without ballast mats. The influence of the important parameters such as the stiffness of the ballast mat, the unsprung vehicle mass, the mass of the track, and the stiffness of the subsoil is investigated. The numerical results are presented as the transfer functions of the total force that is acting on the soil and generating the vibration of the environment. The effectiveness of ballast mats is achieved by division of two of these force functions. The general tendencies for this insertion loss are discussed and a comparison with measurements is given. To come to an improved practical tool for the design of ballast-mat tracks, the finite-element method results are approximated by a simple two-dimensional model of which the solution is given explicitly.

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.