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- Ground vibration (3)
- Railway track (3)
- Field tests (2)
- Hammer impact (2)
- Measurement (2)
- Mitigation (2)
- Slab track (2)
- Soil properties (2)
- Track-soil interaction (2)
- Achsfolgespektren (1)
- Amplitude-charge weight laws (1)
- Amplitude-distance laws (1)
- Assessment (1)
- Ballast track (1)
- Bauteile (1)
- Bauwerke (1)
- Bodendynamik (1)
- Boundary element method (1)
- Brücken (1)
- Building vibration (1)
- Damping (1)
- Dispersion (1)
- Displacements (1)
- Dynamic testing (1)
- Eisenbahnschwingungen (1)
- Elastische Gebäudelagerung (1)
- Evaluation (1)
- Explosion-induced ground vibrations (1)
- Finite element method (1)
- Hammer tests (1)
- Laboratory tests (1)
- MASW (1)
- Modalanalyse (1)
- Modes (1)
- Prediction of explosion induced ground and building vibration (1)
- Prognoseverfahren (1)
- Rechenmodelle (1)
- SASW (1)
- SPAC (1)
- Track damage (1)
- Track damage monitoring (1)
- Train passage (1)
- Train passages (1)
- Under sleeper pads (1)
- Verkehrserschütterungen (1)
- Vibration measurements (1)
- Wave velocity (1)
- Waves (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (5)
- 7.2 Ingenieurbau (5)
Vibration measurements have many causes and many technical and natural sources. Problems can sometimes be solved by short-term measurements, but in many cases, a long-term measurement is necessary. In long-term measurements of days, weeks, months and even years, it is easy to collect a huge quantity of raw data, but at the end, the post-processing of these data can be exhausting (for example one-year vibration data of a wind energy tower). A software has been developed which con-sists of measuring and evaluation routines where the measuring routines can operate different meas-uring systems and different measuring cards. The main advantage of this software is the fact that the interesting evaluations can be integrated in the measuring process so that the characteristics of the vibration can be extracted without storing all the raw data. Only important time segments are stored, for example train passages. The overall concept of the software and the main evaluation routines will be described in some details. Examples of our measurement experience will illustrate the capabilities of the software. 1) Surveying construction work in nearby sensitive buildings (for example an old wind tunnel), including a stable alarm system and meaningful vibration limits. 2) Prediction of train-induced vibration for a planned building to prevent annoyance and to improve the building design. 3) Modal analysis and long term measurements of several single- or multi-span, concrete or steel bridges 4) Modal and wave analysis of coupled floors in a historical building (“Neues Palais” at Potsdam). 5) Soil properties of various measurement sites (different routines to evaluate the dispersion). Moreover, from many projects, amplitudes, frequencies, and attenuation laws have been collected and analysed for the different sources such as vibratory or impact pile driving and ground compaction, demolition work with different machines, blasting in quarries and in tunnel works, bomb and mine clearing.
The damage detection and repair control have become important tasks for ballast and slab tracks. Measurements which compare the damaged and the repaired status of the same track section at different times, or which compare a damaged and an intact track section at the same time, have been successfully performed at some sites in Germany with slab tracks and ballast tracks and compared with the theoretical behaviour of intact and damaged tracks. The loss of contact between the sleeper and the plate, between the plate and the base layer, and some problems with soft or weakened soil have been analysed. The observed results, changes in the time histories of displacements and velocities due to train passages and in the transfer functions (compliances) due to hammer impacts, are encouraging that these measurements can be used to detect track damage. In addition, calculations with the combined finite-element boundary-element method have been used to confirm the conclusions about intact or damaged railway tracks.
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.