TY - JOUR A1 - Auersch, Lutz T1 - Static and dynamic behaviours of isolated and unisolated ballast tracks using a fast wavenumber domain method N2 - 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. KW - Railway track KW - Multi-beam model KW - Layered soil KW - Wavenumber method KW - Track deformation KW - Force transfer KW - Track-soil and vehicle-track resonances PY - 2017 DO - https://doi.org/10.1007/s00419-016-1209-6 SN - 0939-1533 SN - 1432-0681 VL - 87 IS - 3 SP - 555 EP - 574 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-39080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Dynamic axle loads on tracks with and without ballast mats - numerical results of three-dimensional vehicle-track-soil models N2 - 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. KW - Railway track KW - Track dynamic KW - Ballast mat KW - Vibration isolation KW - Insertion loss KW - Finite-element method KW - Track-soil interaction KW - Vehicle-track interaction PY - 2006 DO - https://doi.org/10.1243/09544097F00105 SN - 0954-4097 VL - 220 IS - 2 SP - 169 EP - 183 PB - Institution of Mechanical Engineers CY - London AN - OPUS4-13723 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Dynamic behavior of slab tracks on homogeneous and layered soils and the reduction of ground vibration by floating slab tracks N2 - 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. KW - Railway track KW - Slab track KW - Floating slab track KW - Track-soil interaction KW - Track vibration KW - Ground vibration KW - Force transfer PY - 2012 DO - https://doi.org/10.1061/(ASCE)EM.1943-7889.0000407 SN - 0733-9399 SN - 1943-7889 VL - 138 IS - 8 SP - 923 EP - 933 PB - Soc. CY - New York, NY, USA AN - OPUS4-26860 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Mitigation of railway-induced ground vibration by soft support elements and a higher bending stiffness of the track N2 - The mitigation of train-induced ground vibrations by track solutions is investigated by calculations and measurements. The calculation by a wavenumber domain method includes the correct vehicle–track interaction and the correct track–soil interaction. Some theoretical results for elastic elements and an increased bending stiffness of the track are presented where the force transfer of the track and the vehicle–track interaction are calculated for the high-frequency dynamic mitigation, and the force distribution along the track is calculated for the low-frequency mitigation which is due to the smoother impulses from the passing static loads. Measurement results for the ground vibration near isolated and un-isolated tracks are given for several under-sleeper pads, for under-ballast mats, and for several under-ballast plates and ballast troughs. The elastic elements yield a resonance frequency of the vehicle–track–soil system and a high-frequency reduction of the dynamic axle loads which depends mainly on the softness of the pads or mats and which can be improved by a higher sleeper mass. In addition, all troughs and most of the soft elements show a low-frequency reduction which is attributed to the scattered impulses of the static axle loads. Besides this main contribution of the article, the problem of a soft reference section on a different soil is discussed and recommendations for better ground vibration measurements of mitigation effects are given. KW - Railway track KW - Elastic elements KW - Bending stiffness KW - Ground vibration KW - Mitigation KW - Lowfrequency reduction KW - Axle impulses PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612568 DO - https://doi.org/10.3390/app14031244 VL - 14 IS - 3 SP - 1 EP - 14 PB - MDPI CY - Basel AN - OPUS4-61256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -