Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (134)
- Zeitschriftenartikel (66)
- Beitrag zu einem Tagungsband (66)
- Beitrag zu einem Sammelband (32)
- Forschungsbericht (14)
- Posterpräsentation (13)
- Buchkapitel (1)
Sprache
- Englisch (170)
- Deutsch (149)
- Spanisch (5)
- Französisch (2)
Schlagworte
- Ground vibration (39)
- Layered soil (13)
- Slab track (11)
- Mitigation (10)
- Railway track (10)
- Bahnerschütterungen (9)
- Erschütterungen (9)
- Finite-element boundary-element method (9)
- Track-soil interaction (9)
- Train passage (9)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (82)
- 7.2 Ingenieurbau (82)
Eingeladener Vortrag
- nein (134)
Durch Schienenverkehr angeregte Wellenausbreitung durch den Boden - Stand der Simulationsmethoden
(2014)
The layered soil is calculated in the frequency wavenumber domain and the solutions for fixed or moving point or track loads follow as wavenumber integrals. The resulting point load solutions can be approximated by simple formula. Measurements yield the specific soil parameters for the theoretical or approximate solutions, but they can also directly provide the point-load solution (the transfer function of that site). A prediction method for the train-induced ground vibration has been developed, based on one of these site-specific transfer functions. The ground vibrations strongly depend on the regular and irregular inhomogeneity of the soil. The regular layering of the soil yields a cut-on and a resonance phenomenon, while the irregular inhomogeneity seems to be important for high-speed trains. The attenuations with the distance of the ground vibration, due to point-like excitations such as vibrator, hammer, or train-track excitations, were investigated and compared. All theoretical results were compared with measurements at conventional and high-speed railway lines, validating the approximate prediction method.
En este artículo se presentan 2 metodologías basadas en las formulaciones del Método de los Elementos de Contorno y del Método de los Elementos Finitos para estudiar el efecto de la interacción suelo-estructura en el comportamiento dinámico de edificaciones. Se ha estudiado la respuesta de un edificio de 3 plantas producida por un campo de ondas incidente con los 2 métodos propuestos. Los resultados obtenidos presentan un buen grado de acuerdo entre ellos. A partir de estos resultados se ha validado un modelo aproximado para estudiar este tipo de problemas y se han examinado diferentes tipologías de edificaciones. Las conclusiones alcanzadas muestran que la respuesta global de las estructuras se debe a la deformación de los forjados y depende de su superficie, de las condiciones de apoyo y del acoplamiento con los forjados de la misma planta. Del mismo modo, se ha observado un acoplamiento del comportamiento de pilares y forjados cuando las rigideces de ambos son similares.----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- This paper presents 2 methodologies based on the Boundary Element Method and the Finite Element Method to study soil-structure interaction effect on building behaviour. A 3-story building response induced by an incident wave field is studied using both methods. The results obtained show a good agreement. Then, a simplified model is validated from these methods and several buildings are analysed. Conclusions show that structural responses are due to floor deformation, and depend on their area, support conditions and coupling. A coupling between floors and columns when both elements have similar stiffness is also observed.
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.
Messungen bei Fern- und Hochgeschwindigkeitsbahnen aus verschiedenen Ländern (Portugal, Spanien, Belgien, Großbritannien, Deutschland, Schweiz, China, Japan u.a.) sollen die besondere Wichtigkeit eines mittelfrequenten Erschütterungsanteils zeigen. Relativ einheitlich werden dabei drei zusammenhängende Terzen mit angehobenen Amplituden beobachtet. Dieser Erschütterungsanteil dominiert mit zunehmender Entfernung vom Gleis das Frequenzspektrum der Erschütterungen. Die hochfrequenteren Anteile nehmen aufgrund der Materialdämpfung des Bodens stärker ab, die tieffrequenteren Anteile aus der sogenannten Quasistatik, der Vorbeifahrt der statischen Achslasten, verschwinden innerhalb der ersten zehn Meter vom Gleis fast vollständig. Die Frequenzcharakteristik des mittelfrequenten Erschütterungsanteils wird durch die Achsfolge des Zuges bestimmt. Im Terzmaßstab ist die Achsfolge im Drehgestell maßgeblich für die Ausprägung von zwei Amplitudenminima, die den Frequenzbereich eingrenzen. Diese Achsfolgespektren sind auch bei Brückenschwingungen von Bedeutung. Sie können die schwächere oder stärkere Anregung einzelner Brückeneigenschwingungen regeln. Die Ursachen der Boden- oder Brückenschwingungen sind mit den Achsfolgespektren noch nicht geklärt. Bei der Brücke und beim Boden können kurzwelligere Gleislagefehler (auch Radunrundheiten 1. Ordnung) Fahrzeugbeschleunigungen und damit dynamische Kräfte auf das Gleis erzeugen. Bei der Brücke ist die diskontinuierliche Auf- und Abfahrt der Achsen ebenfalls eine relevante Anregung, während die Kraftimpulse auf das Gleis, die durch die Achsüberfahrten entstehen, für die Wellenausbreitung im Boden von Bedeutung sind. Heterogene Böden oder Gleise ergeben einen Zerstreuanteil der Achsüberfahrtimpulse. Fallbeispiele mit verschiedenen Böden und verschiedenen Fahrgeschwindigkeiten werden ausgewertet, um die Ursachen und Gesetzmäßigkeiten des mittelfrequenten Erschütterungsanteils zu erkennen.
Die Bedeutung von Eisenbahn-Achsüberfahrten für die Bodenerschütterungen und Brückenschwingungen
(2016)
Messungen bei Fern- und Hochgeschwindigkeitsbahnen aus verschiedenen Ländern (Portugal, Spanien, Belgien, Großbritannien, Deutschland, Schweiz, China, Japan u.a.) sollen die besondere Wichtigkeit eines mittelfrequenten Erschütterungsanteils zeigen. Relativ einheitlich werden dabei drei zusammenhängende Terzen mit angehobenen Amplituden beobachtet. Dieser Erschütterungsanteil dominiert mit zunehmender Entfernung vom Gleis das Frequenzspektrum der Erschütterungen. Die hochfrequenteren Anteile nehmen aufgrund der Materialdämpfung des Bodens stärker ab, die tieffrequenteren Anteile aus der sogenannten Quasistatik, der Vorbeifahrt der statischen Achslasten, verschwinden innerhalb der ersten zehn Meter vom Gleis fast vollständig. Die Frequenzcharakteristik des mittelfrequenten Erschütterungsanteils wird durch die Achsfolge des Zuges bestimmt. Im Terzmaßstab ist die Achsfolge im Drehgestell maßgeblich für die Ausprägung von zwei Amplitudenminima, die den Frequenzbereich eingrenzen. Diese Achsfolgespektren sind auch bei Brückenschwingungen von Bedeutung. Sie können die schwächere oder stärkere Anregung einzelner Brückeneigenschwingungen regeln. Die Ursachen der Boden- oder Brückenschwingungen sind mit den Achsfolgespektren noch nicht geklärt. Bei der Brücke und beim Boden können kurzwelligere Gleislagefehler (auch Radunrundheiten 1. Ordnung) Fahrzeugbeschleunigungen und damit dynamische Kräfte auf das Gleis erzeugen. Bei der Brücke ist die diskontinuierliche Auf- und Abfahrt der Achsen ebenfalls eine relevante Anregung, während die Kraftimpulse auf das Gleis, die durch die Achsüberfahrten entstehen, für die Wellenausbreitung im Boden von Bedeutung sind. Heterogene Böden oder Gleise ergeben einen Zerstreuanteil der Achsüberfahrtimpulse. Fallbeispiele mit verschiedenen Böden und verschiedenen Fahrgeschwindigkeiten werden ausgewertet, um die Ursachen und Gesetzmäßigkeiten des mittelfrequenten Erschütterungsanteils zu erkennen.
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.
Les methods numerique et experimentelle sont les elements finis pour le sol infini et les mesures pour les parametres du sol, la vitesse des ondes et l'amortissement materielle. Les resultats sont les reductions dues aux elements elastiques, les effets de la trace elevee ou basse, et les reponses des batiments mesurees.
Erschütterungen durch Schienenverkehr – Messergebnisse, Quellstärken und Amplituden-Abstands-Gesetze
(1986)
Es werden Messergebnisse und theoretische Studien vorgetragen, die sich mit der Erschütterungsstärke in der Nähe von Bahnlinien und deren Abnahme mit der Entfernung beschäftigen. Durch die Ausdehnung der Anregung über die Zuglänge ergibt sich bei gleichphasiger Anregung ein Bereich konstanter Amplituden, bei zufälliger Phasenlage eine gleichmäßige Abnahme, die schwächer als bei einer Punktlast ist. Die Messungen belegen, dass es eine starke Abnahme für die Vorbeifahrt der statischen Achslasten gibt, so dass dieser Anteil spätestens in 10 m Abstand unbedeutend ist. Am Gleis selbst ist dieser (statische) Anteil dominant.
Some results of our measurements of the Intercity experimental are presented together with simulated results and their interpretation. Three frequeny ranges could be measured and calculated: low frequencies which decrease very rapidly with distance (the quasi-static part), high frequencies (mainly due to the sleeper passage), and a mid-frequency which has the weakest attenuation with distance and is therefore dominant at the far field. Mono-frequent excitations get a wide frequency band due to the Doppler effect of the moving high-speed train.
Der Erhalt und die Weiterentwicklung der Verkehrsinfrastrukturen werden auch zukünftig einen Investitions- und Forschungsschwerpunkt in Deutschland bilden. Gemäß den aktuellen Entwicklungsprognosen sowohl der Bundesregierung als auch der Deutschen Bahn wäre bei unveränderten Marktanteilen der Bahn eine Zunahme insbesondere des Güterverkehrs in den kommenden 10 Jahren um ca. 50% zu erwarten. Dieser Zuwachs erfordert erhebliche Entwicklungen sowohl in der technischen Konstruktion der Fahrwege als auch im Erschütterungs- und Lärmschutz infolge des Schienenverkehrs.
A survey of the phenomena and methods for floor vibrations is presented. Experimental results of floor vibrations are shown for many floors in six different buildings. The signals have been evaluated for waves and modes by simple procedures. General rules have been established between the material and the area of a specific floor, and its local eigenfrequency. The damping values of the floor vibrations have been found between D = 1 and 10 % where somewhat higher values have been measured for wooden floors, and a weak correlation with the eigenfrequency has been established. The velocities of bending waves propagating in a storey and the attenuation with distance in the building have been analysed. A considerable transfer of vibration from one room to far away parts of the building has been found in the studied buildings with concrete and wooden floors. An example building has been analysed for modes of coupled floor bays. The strong coupling of similar neighbouring floor bays would yield a wide band of global resonance frequencies. The measured wooden floor exhibits a weak coupling of the neighbouring floor bays and a narrower band of eigenfrequencies. A special method has been tested with the impulse measurements to estimate the coupled eigenmodes in presence of the high damping. From the ambient measurement, a low-frequency vibration mode has been detected which includes the vibration of the whole building and the soil. The coupling of floors to other floors and the whole building is an important phenomenon of structural dynamics which should be observed for the prediction of vibration due to internal and external sources.
Train-induced ground vibration can be excited by wheel and track irregularities and by two kinds of irregularities of the soil, by geometric irregularities or by the spatially varying soil stiffness. For both types of irregularities, the effective track irregularity on top of the track is calculated in wavenumber domain and with wavenumber integrals. For a general multi-beam track model, the wavenumber integrals are solved numerically. The irregularities of the soil are filtered by the track when transferred from the bottom to the top of the track. The high-wavenumber irregularities are strongly reduced due to the bending stiffness of the track and the compliance of the support. In addition, soft track elements reduce directly the stiffness variation of the support. Therefore, the mitigation effect of elastic track elements for these excitation components seems to be important. For under-sleeper pads and slab tracks, calculation and measurements are presented including additional excitation components and the dynamic vehicle–track interaction, and the relevance of the excitation mechanisms is discussed based on the dynamic forces which are acting on the ground. Due to the restricted amplitudes, the parametric excitation by the stiffness variation seems to be less important than the geometric irregularities. The calculations yield the correct trends of the measurements and many details of the measured ballast, slab, and under-sleeper-pad tracks.
Train-induced ground vibrations are generated by static and dynamic axle loads which can be calculated by vehicle-track-soil models and the vehicle and track irregularities. A fast prediction method has been developed which uses approximate transfer functions of layered soils. In the present contribution, this prediction method is used for the inverse calculation of the axle-load spectra from the measured ground vibration. The layered soils of some measuring sites show very differing ground vibration spectra in the amplitude range of 0.0001–1.0 mm/s as a consequence of the soft layer and stiff half-space, differing layer frequencies, as well as the far- and near-field measuring points. The back-calculation, however, yields axle-load spectra within a single order of magnitude around 1 kN. Axle-box measurements confirm the amplitude level of the axle loads. This standard axle-load spectrum can be used for a basic prediction at a new site. The separation of train and site-specific components allows a better evaluation of railway vibrations, for example, of different trains and different tracks. By eliminating the effects of differing soil characteristics, an important mid-frequency component has been found which lies between 8 and 32 Hz depending on the train speed. The origin of this dominant mid-frequency component is discussed using advanced prediction methods like moving constant loads, scattered axle impulses and axle-sequence spectra.
Deckenschwingungen stellen in der Regel das größte Problem bei Erschütterungsgutachten dar. In diesem Übersichtsbeitrag werden folgende Aspekte der Deckenschwingungen mit einfachen bis komplexen Rechenmodellen dargestellt.
Die Resonanzanregung der Decken hängt von der Phasenlage der Auflagerschwingungen ab. Der Wellenlauf der anregenden Freifeldbodenschwingungen kann die Resonanzstärke deutlich verringern. - Der Wellenlauf kann bei Pfahl- oder Plattengründungen zu Abminderungen der Freifeldamplituden führen (kinematische Bauwerk-Boden-Wechselwirkung). - Die Steifigkeit des Untergrundes hat einen starken Einfluss auf die Resonanzstärke. Dies hat einerseits mit der Abstrahlungsdämpfung zu tun, andererseits auch mit einer Schwingungstilgung. Die Tilgung kann in einem vereinfachten Wand-Decken-Modell mit einer einheitlichen Deckeneigenfrequenz oder realistischer mit einem Eigenfrequenzband berechnet werden. In einem schmalen Frequenzband vor der Deckeneigenfrequenz können weitere (Wand-) Eigenfrequenzen und nach der Deckeneigenfrequenz eine Frequenzlücke auftreten. Normalerweise nehmen die Deckenamplituden mit der Höhe im Gebäude zu. In der Frequenzlücke hingegen nehmen die Amplituden mit der Höhe ab. - Benachbarte Deckenfelder können gemeinsame Deckeneigenfrequenzen besitzen, vor allem wenn sie die gleichen Abmessungen haben. Man bekommt dann ein Band von Deckeneigenfrequenzen. - Bei einer Schwingungsanregung im Gebäude auf einer Decke schwingen auch die benachbarten Deckenfelder mit. Im Frequenzbereich lassen sich Übertragungsfunktionen darstellen, im Zeitbereich können Amplituden-Abstandsgesetze betrachtet werden. - Bei großen Stützenbauwerken treten häufig Kopplungen der Decken verschiedener Stockwerke auf. - Mit den verschiedenen Methoden lassen sich typische Gesetzmäßigkeiten für die Amplituden und Frequenzen der Deckenschwingungen ableiten.
The reduction of train-induced ground vibration by elastic elements such as rail pads and sleeper pads has been analyzed by a combined finite-element boundary-element method. The dynamic compliance of the track, the transfer function of the total force on the ground and the ground vibration ratios have been calculated for a variety of isolated and un-isolated track systems. It has been found that the soil force transfer, which describes the excitation force of the soil, is an appropriate quantity to predict the reduction of the ground vibration and the effectiveness of isolated tracks. All force transfer functions of isolated tracks display a vehicletrack resonance where the wheelset on the compliant track is excited by wheel and track irregularities. At higher frequencies, considerable reductions of the amplitudes are observed as the benefit of the resilient element. The influence of the stiffness of the rail or sleeper pads, the ballast and the soil, and the mass of the sleeper and the wheelset on the resonance frequency and the reduction has been investigated. Sleeper pads are advantageous due to the higher mass that is elastically supported compared to the rail-pad track system. The combination of elastic rail and sleeper pads has been found to be disadvantageous, as the second resonance occurs in the frequency range of intended reduction.
The computation of the wave propagation in homogeneous and layered soils can be performed by a numerical integration in wavenumber domain. The numerical difficulties of an infinite integral and an integrand with poles can be solved. But if this computation must be repeated for many distances, many frequencies, many loads, or many soil models, it becomes a time consuming task which is not acceptable for a user-friendly prediction tool for railway induced ground vibration. Therefore, an approximate method for the computation of the wave field has been developed. The computation consists of several steps. At first, an approximate dispersion profile is calculated according to rules which have been derived from exact solutions. Secondly, the dispersion is used to achieve the amplitude for a certain frequency and a certain distance by calculating the approximate solution of a corresponding homogeneous half-space. Thirdly, three layer corrections are added which include lowfrequency near-field effects, high-frequency far-field effects, and a resonance amplification around the layer frequency. This procedure yields the wave field due to a point load. For a train load, many of these point-load responses have to be summed up, and a frequencydependant reduction factor has to be multiplied to incorporate the effect of the load distribution along and across the track. - The prediction method is applied to real sites, and the appropriate soil models are identified by approximating the measured transfer functions (frequency-dependant amplitudes) which is presented as an alternative to the approximation of the dispersion (frequency-dependant wave velocities). These examples demonstrate the general behavior of layered soils: the low amplitudes of the stiff half-space at low frequencies, the high amplitudes of the softer layer at high frequencies, the strong increase of amplitudes and a possible resonance amplification at mid frequencies. The material damping of the layer yields a strong attenuation of the amplitudes with the distance for high frequencies. The response depends strongly on the resonance or layer frequency which is shown for different layer depths and velocities always in good agreement with measurements. The layer frequency can be of immense influence if train-speed effects are analysed in a layered soil. The good agreement with many measurements in this contribution as well as in the references validates the prediction of ground vibration based on the theory of a layered half-space.
The ground vibrations, which are generated by trains on different tracks, have been calculated by finite-element boundary-element models. The ballasted track is modelled in detail by the finite element method. The infinite soil is modelled by the boundary element method as a homogeneous or layered half-space. The track-soil system is coupled to a simple rigid mass model of the vehicle so that the vehicle-track interaction is completely included. Transfer functions are calculated in frequency domain without and with vehicle-track interaction, the compliance of the track and the mobilities of the soil at different distances from the track. Finally, the ratios between the ground vibration amplitudes with and without mitigation measures are calculated to quantify the effectiveness of the mitigation measures.
Tracks with under-sleeper pads have been investigated in a wide parameter study for the RIVAS project. The main parameters that influence the reduction of ground vibration are the stiffness of the under-sleeper pad, the mass and the width of the sleeper. The softest sleeper pad yields the best reduction of the ground vibration. The influence of the sleeper mass is not so strong, as the characteristic frequency is ruled by the mass of the sleeper and the mass of the wheelset as well.
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.
The vibrations of soil and foundations are demonstrated for different types of loading. Train-induced ground vibrations are studied in a measurement campaign where a test train has run with regularly varied speeds. The measured train-induced soil vibration at 2 to 100 m distance from the track is compared with the wave propagation due to hammer excitation and with the theoretical wave field. The strong influence of the soil and the train speed on the amplitudes and frequencies of the vibration has been analysed for passages of the locomotive and the carriages. - The generation of ground vibration by strong explosions has been studied on a large testing area with sandy soil. The propagating waves were measured in a regular grid of measuring points in 10 to 1000 m. Therefore, the dominance of certain waves at certain distances and the changes of compressional waves and Rayleigh waves could clearly be observed. The results are compared with impulse hammer measurements in the range of 5 to 50 m. - A drop test facility has been built on the testing area of the Federal Institute of Materials Research and Testing (BAM). Heavy masses (containers) of up to 200 t can be dropped from 10 m height on a big reinforced concrete foundation. The foundation was instrumented by accelerometers, strain gauges and pressure cells to give information about the loading condition and by geophones to measure the vibration of the surrounding soil and building. Both excitation processes, the release of the mass and the impact, produce high vibration amplitudes. On a smaller drop foundation, the influence of the drop height and the target stiffness has been studied more systematically.
The dynamics of un-isolated and isolated ballast tracks have been analysed by multi-beam models for the track and by a layered half-space model for the soil. The solution is calculated in frequency-wavenumber domain and transformed back to space domain by a wavenumber integral. This is a faster method compared to other detailed track-soil interaction methods and almost as fast as the widely used Winkler-soil method, especially if the compliances of the soil have been stored for repeated use. Frequency-dependent compliances and force transfer functions have been calculated for a variety of track and soil parameters. The ballast has a clear influence on the high-frequency behaviour whereas the soil is dominating the low-frequency behaviour of the track. A layering of the soil may cause a moderate track-soil resonance whereas more pronounced vehicle-track resonances occur with elastic track elements like rail pads, sleeper pads and ballast mats. Above these resonant frequencies, a reduction of the excitation forces follows as a consequence. The track deformation along the track has been analysed for the most interesting track systems. The track deformation is strongly influenced by the resonances due to layering or elastic elements. The attenuation of amplitudes and the velocity of the track-soil waves change considerably around the resonant frequencies. The track deformation due to complete trains have been calculated for different continuous and Winkler soils and compared with the measurement of a train passage showing a good agreement for the continuous soil and clear deviations for the Winkler soil model.
Die Grundidee einer Schwingungsminderung ist es eine tiefe Eigenfrequenz der Struktur zu erreichen, so dass höhere Frequenzen abgemindert werden. Das gilt für die Minderung an der Quelle, zum Beispiel einem Eisenbahngleis, und für die Minderung am Empfänger, dem Gebäude. Die Eigenfrequenz ermittelt man aus dem Verhältnis der Auflagersteifigkeit und der Masse. Wie ist die Masse bei einem Gebäude zu wählen? Und wie ist die Untergrund-steifigkeit zu berücksichtigen? Als Referenzsituation ohne Minderungsma߬nahme? Der Beitrag bringt Rechenergebnisse zu abgefederten Gebäuden mit einfachen und komplexen (FE-) Modellen, Mess- und Rechenergebnisse zur Schwingungsübertragung von unabge-federten Gebäuden. Es wird der Einfluss der Abstimmfrequenz, der Bodensteifigkeit und der „starren“ Gebäudemasse untersucht. Die komplexen Gebäudemodelle erlauben, neben der Berechnung einer elastischen Gebäudelagerung, auch die Variation von Gebäudepara¬metern zur Reduktion der Deckenschwingungen. Den Ergebnissen bei der Erschütterungs-übertragung in Gebäude werden zwei ähnliche Beispiele zur elastischen Maschinenlagerung und zur elastischen Gleislagerung gegenübergestellt.
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.
This contribution presents experimental methods to detect track damage. At BAM (Federal Institute of Material Research and Testing), a measuring car with a measuring system of 72 channels, geophones, mountings, cables, harmonic and impulsive exciters is used for dynamic measurements of the track, the soil and buildings. An instrumented hammer allows force measurements and to evaluate transfer functions of the track, and the soil. Wave measurements are used to identify the soil characteristics. Train passages are measured at the track and for the train induced ground vibrations. In addition to these in situ options, tests of tracks or track elements can be performed in a large laboratory.