An efficient methodology based on two-and-a-half-dimensional finite element and boundary element methods for ground-borne vibration radiated by underground railway tunnels and the re-radiated noise emitted inside them

• Autores: Dhananjay Ghangale
• Directores de la Tesis: R. Arcos (dir. tes.), J. Romeu (dir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2019
• Idioma: español
• Tribunal Calificador de la Tesis: Evangelos Ntotsios (presid.), Teresa Pàmies Gómez (secret.), Pedro Miguel Barbosa Alves (voc.)
• Programa de doctorado: Programa de Doctorado en Ingeniería Mecánica, Fluidos y Aeronáutica por la Universidad Politécnica de Catalunya
• Materias:
  • Física
    • Acústica
      • Vibraciones
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• Resumen

  • This thesis presents a methodology for assessing induced ground-borne vibration due to Underground railway infrastructures in the context of an urban environment. The methodology is based on a comprehensive numerical approach for modelling track/tunnel/soil systems considering a full-space model of the ground. This approach is formulated in the wavenumber-frequency domain and it is based on coupled finite element-boundary element method. An axisymmetric formulation to deal with circular underground railway tunnels is included in the approach in order to improve the computational speed of the methodology. This formulation can also be used for other types of railway tunnels if a circular boundary of the boundary element mesh is considered. The developed approach also includes asymptotic solutions of the Green's functions for large wavenumbers which results in an improvement of the accuracy of the overall methodology. A hybrid methodology which uses semi-analytical solutions of a cavity in a full-space in conjunction with the previously described approach has been developed with the aim of computing the energy flow radiated upwards by underground railway tunnels. Since this methodology uses finite elements to model the tunnel structure, its modelling detail is higher than the previously developed methodologies based on semi-analytical modelling of the tunnel structure. This hybrid methodology has been specifically designed for the study the vibration radiation of railway tunnels, the comparison between them and for the study of the insertion loss of mitigation measures at the sources, as soft rail-pads, under-ballast or under-slab mats, dynamics vibration absorbers, etc. In this thesis, this hybrid methodology is used to perform a comparison of the energy flow radiated upwards by various types of underground railway tunnels. Finally, a modelling approach for the re-radiated noise induced by a train passage inside railway tunnels is presented. This approach is based on the weak coupling between the comprehensive numerical approach for modelling track/tunnel/soil previously described and a two-and-a-half-dimensional boundary element method model for interior acoustics. Using this modelling approach, the influence of the fastener stiffness on the noise and vibration levels inside a simple tunnel as well as the relation between the noise emitted by the rails or the tunnel structure is investigated and discussed.