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- Ground vibration (11)
- Finite-element boundary-element method (4)
- Layered soil (4)
- Railway track (4)
- Building vibration (3)
- Hammer impact (3)
- Slab track (3)
- Track-soil interaction (3)
- Vibration measurements (3)
- Container loading (2)
- Drop test (2)
- Field tests (2)
- Foundation load (2)
- Layered soils (2)
- Measurement (2)
- Mitigation (2)
- Soil properties (2)
- Soil-building interaction (2)
- Soil-wall-floor model (2)
- Train passage (2)
- Train speed (2)
- Train-induced ground vibration (2)
- Vehicle-track interaction (2)
- Vehicle-track-soil interaction (2)
- 1-D insertion loss (1)
- 2-span bridge (1)
- Achsfolgespektren (1)
- Amplitude-charge weight laws (1)
- Amplitude-distance laws (1)
- Apartment building (1)
- Assessment (1)
- Attenuation (1)
- Axle impulses (1)
- Axle loads (1)
- Axle sequence (1)
- Axle-sequence spectrum (1)
- Ballast track (1)
- Ballast tracks (1)
- Bauteile (1)
- Bauwerke (1)
- Boundary element method (1)
- Bridge resonance (1)
- Bridge track (1)
- Brücken (1)
- Column/wall resonance (1)
- Continuously inhomogeneous soils (1)
- Damping (1)
- Dispersion (1)
- Displacements (1)
- Dynamic testing (1)
- Evaluation (1)
- Excitation forces (1)
- Explicit Green´s functions (1)
- Explosion-induced ground vibrations (1)
- FEBEM and simplified methods (1)
- Filter effects (1)
- Finite element method (1)
- Finite element models (1)
- Floating slab track (1)
- Floor amplification (1)
- Floor resonance (1)
- Force transfer (1)
- Foundation reduction (1)
- Freight train (1)
- Ground vibration measurements (1)
- Hammer tests (1)
- High-Rise Building (1)
- High-speed train (1)
- Inertial Interaction (1)
- Irregular ballast (1)
- Irregular soil (1)
- Irregularities (1)
- Kinematic Interaction (1)
- Laboratory tests (1)
- Long-span bridge (1)
- MASW (1)
- Measurements (1)
- Mitigation measures (1)
- Modal force spectrum (1)
- Modalanalyse (1)
- Modes (1)
- Office building (1)
- Office tower (1)
- Passenger train (1)
- Pile Foundation (1)
- Pile bending stiffness (1)
- Pile foundation (1)
- Plate-soil interaction (1)
- Prediction of explosion induced ground and building vibration (1)
- Propagation from a tunnel (1)
- Radiation damping (1)
- Railway (1)
- Railway bridge (1)
- Railway induced ground vibration (1)
- Railway tracks (1)
- Railway tunnel (1)
- Railway vibration (1)
- Randomly heterogeneous soil (1)
- Residential building (1)
- SASW (1)
- SPAC (1)
- Scattering (1)
- Simple prediction (1)
- Soil stiffness (1)
- Soil-building resonance (1)
- Surface Foundation (1)
- Surface line (1)
- Surface-tunnel reduction (1)
- Track compliance (1)
- Track damage (1)
- Track damage monitoring (1)
- Track irregularities (1)
- Track vibration (1)
- Train passages (1)
- Transfer function (1)
- Tunnel track (1)
- Tunnel vibration (1)
- Tunnel-pile transfer (1)
- Under sleeper pads (1)
- Under-ballast plate (1)
- Varying stiffness (1)
- Vibration measurement (1)
- Vibration reduction (1)
- Wave excitation (1)
- Wave velocity (1)
- Wavenumber integrals (1)
- Waves (1)
- Wind energy tower (1)
- floor vibration (1)
- ground vibration (1)
- mitigation (1)
- modal analysis (1)
- railway track (1)
- track-soil interaction (1)
- undersleeper (1)
- wave analysis (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (18)
- 7.2 Ingenieurbau (18)
Usually, geometric irregularities are considered as the main cause of ground vibrations from trains. A varying stiffness of the track, the track support and the soil can also generate ground vibrations. The regular stiffness variation of the track on and between the sleepers results in a deterministic dynamic axle load. The random stiffness variation of the track support yields also dynamic axle loads which are generated by the acceleration of the unsprung mass (from the varying wheel displacements under the static axle load). The random stiffness variation has a second effect. The pulses from the passage of the static axle loads are superposed regularly to the quasi-static response, but also irregularly to yield a “scattered” part of the axle pulses. The same holds for a random variation of the soil stiffness. All these effects of stiffness variations have been calculated by wavenumber-domain multi-beam track models, a random finite-element soil model and the superposition of axle impulses in a stochastic simulation. The results are confronted with many measurements at different sites. It is concluded that the stiffness variation of the track and the soil generate an important ground vibration component near railway lines.
Prediction of building noise and vibration – 3D finite element and 1D wave propagation models
(2021)
Construction work or traffic excite nearby buildings, and the perceptible or audible vibration can be a nuisance for the inhabitants. The transfer of the vibration from the free field to the building has been calculated by the finite element method for many models in consultancy and research work. The analysis for all storeys of certain building points such as walls, columns and floors unveiled some rules, some typical modes, and some wavetype responses. A simplified building-soil model has been created, which includes well these effects of building-soil resonance, wall/column resonance, floor resonances, and the high-frequency reduction. The model consists of one wall for a wall-type apartment building or a column for each specific part (mid, side or corner) of a column-type office building. The building response in the high-frequency (acoustic) region is calculated as mean values over all storeys and over wider frequency bands, by wave-type asymptotes of an infinitely tall building, and by the soil to wall ratio of impedances. The secondary noise is predicted by Transfer values between the building vibration (center of floors, walls at a room corner) and the sound pressure.
Measurements at the foundation, the surrounding soil and nearby buildings have been done during several drop tests of different containers on different foundations. The first measurements have been done on a big foundation where it should be guaranteed that the foundation is rigid and the container is tested properly. It was controlled that the foundation does not absorb more than 2 percent of the energy of the container. Most of the drop energy is lost in shock absorbers. Later on, a smaller drop test facility has been built on the ground but inside an existing building. It had to be controlled by prediction and measurements that the drop test will not damage the building. Tests from different heights on soft, medium, and stiff targets have been done to find out rules which allow to identify acceptable and unacceptable drop tests. Later on, the biggest drop test facility has been built for masses up to 200 t. It was necessary for the design of the foundation to estimate the forces which occur during the drop tests. On the other hand, the acceptable tests should be selected and controlled by measurements where the impact duration is important. Different sensors, accelerometers, accelerometers with mechanical filters, geophones (velocity transducers), strain gauges, and pressure cells have been applied for these tasks. The signals have been transformed to displacements which proved to be best suited for the interpretation of the impact mechanism. Modell calculations have been used to check and understand the dynamic measurements. The simplest law is the conservation of the momentum which is a good approximation if the impact is short. If the soil under the foundation has an influence on the deceleration of the container, the maximum foundation velocity is lower than the simple estimation. The amplitudes of the foundation could also be estimated from the ground vibrations and their amplitude-distance law.
Abstract. 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.
Explosion-induced ground vibrations have been measured at several places. Results about the wave propagation are shown in this contribution. The particle velocities of the soil have been measured at up to 1000 m distance from the explosion and are presented as time records (seismograms) and one-third octave band spectra (transfer functions). The results are compared with the results of hammer impacts. The seismograms clearly show different wave types, compressional waves of the air, the water and the soil, and the Rayleigh wave. The hammer impacts yield good results up to 100 m and incorporate higher frequencies at about 50 Hz, whereas the explosion results in a ground vibration with frequencies around 10 Hz and a longer range of influence. Explosion and hammer excitations are evaluated for the wave velocities of the soil by using the wavenumber and the spatial auto-correlation method. The attenuation of the ground vibration amplitudes A with distance r can well be presented by a power law A ~ r -q. This type of amplitude-distance law and the corresponding power q > 1 are substantiated in the contribution. The influence of the charge weight W is evaluated as an additional power law A ~ W -p for each measuring site. The power is found quite similarly around q 0.6 as all sites have a medium soft soil such as sand and clay. The obtained amplitude-charge-distance law can be used to predict the explosion-induced ground and building vibrations at other sites.
Measured train passages and hammer impacts in combination with track-soil calculation have been successfully used for the detection of damaged slab tracks. This approach is now extended to intact slab and ballast tracks. The vibrations of many tracks have been measured at several levels from rail, sleeper, track plate, base plate, base layer to the subsoil by velocity or acceleration sensors. The time histories have to be integrated once or twice to get the displacements. The displacement signals include an arbitrary time-dependent shift which must be eliminated or respected in the interpretation. On the other hand, the calculation of slab and ballast tracks have been done in frequency-wavenumber domain. The displacements along the track and the frequency-dependent compliance transfer functions can be calculated. The latter can be compared with the results of the hammer impacts on the track. The deformation of the track can be transformed to time histories for a whole train and compared to the measured train passages. Many slab (and ballast) tracks have been measured at different sites. The displacements of the tracks are presented, and the following parameters have been analysed in the measurement results: slab track vs. ballast track, different types of slab tracks, damaged slab tracks, different trains, switches at different measuring points, an elastic layer, the mortar layer, different soils at different places. The soil should have the dominant influence on the track-plate displacements. Slab and ballast track yield also big differences in maximum displacement and width of deformation. Some of the preceding aspects will be analysed in comparison of measurement and theory.
The present contribution evaluates four measuring series made by the Federal Institute of Material Research and Testing for the relations between train speed and ground vibration amplitudes. This experimental evaluation is supported by the simulation of the train passages at the different sites by using appropriate excitation mechanisms and forces as well as layered soil models which have been derived from impact measurements at each site.