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- Englisch (26) (entfernen)
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- Slab track (6)
- Field tests (5)
- Hammer impact (5)
- Ground vibration (4)
- Railway track (4)
- Track damage (4)
- Track-soil interaction (4)
- Train passage (4)
- Vibration measurements (3)
- Amplitude-distance laws (2)
- Ballast track (2)
- Boundary element method (2)
- Displacements (2)
- Dynamic testing (2)
- Environmental vibrations (2)
- Finite element method (2)
- Hammer tests (2)
- Measurement (2)
- Mitigation (2)
- Soil properties (2)
- Track vibration (2)
- Train passages (2)
- Achsfolgespektren (1)
- Amplitude-charge weight laws (1)
- Assessment (1)
- Axle box measurements (1)
- Bauteile (1)
- Bauwerke (1)
- Brücken (1)
- Building vibration (1)
- Compliance function (1)
- Damping (1)
- Dispersion (1)
- Evaluation (1)
- Explosion-induced ground vibrations (1)
- Laboratory tests (1)
- MASW (1)
- Material damping (1)
- Modalanalyse (1)
- Modes (1)
- Monitoring (1)
- Prediction of explosion induced ground and building vibration (1)
- Railway measurement campaign (1)
- Rayleigh wave (1)
- SASW (1)
- SPAC (1)
- Scattering damping (1)
- Switch (1)
- Track damage monitoring (1)
- Track deflection (1)
- Turnout (1)
- Under sleeper pads (1)
- Vehicle-track interaction (1)
- Vibration excitation (1)
- Wave attenuation (1)
- Wave theory of attenuation (1)
- Wave velocity (1)
- Waves (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (9)
- 7.2 Ingenieurbau (9)
Eingeladener Vortrag
- nein (2)
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.
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.
There is a strong need for cost-effective mitigation measures for
turnouts. SBB has initiated a series of examinations using different methodologies to gain a deeper understanding of the excitation mechanisms at low frequencies, in addition to that obtained in the RIVAS project. To date it is not yet clear what constitutes a complete measurement data set that would enable understanding most of the vibration excitation mechanisms in turnouts. Increasing vibration at turnouts in comparison to normal track is observed for all measured frequencies.
The different methodologies are presented in the paper. Under-sleeper pads (USP) are a cost-effective method to reduce vibration at frequencies above 63 Hz (1/3 octave), but there is probably no improvement for frequencies below 63 Hz. A first test of new frog geometry did not show relevant improvements in Vibration emission in comparison to a reference frog geometry. Axle box acceleration measurements are an interesting method to identify defects in a turnout. A specialized measurement system of rail roughness could identify certain geometry Problem areas for some frogs. Noise increases also are observed at turnouts for frequencies ranging between 80 to 1000 Hz. The use of railway source models to calculate
contact forces for ballasted track and turnouts seems promising, in particular for understanding the influence of ground.