Análise numérica da alteração do estado de tensão geomecânico induzida pelo tráfego ferroviário

Tese de mestrado integrado. Engenharia Civil (Área de Especialização de Geotecnia). Faculdade de Engenharia. Universidade do Porto. 201

A methodology for the calculation of the noise radiated by the rails and the tunnel structure in railway tunnels

In this paper, a robust and fast numerical methodology to compute re-radiated noise in underground railway tunnels is proposed. In this study, the noise analysis does not account for the noise radiation from the train wheels, the rest of the rolling stock structure and the aerodynamic noise. The method is based on decoupled approach, where the acoustic and elastodynamic problems are solved separately on the assumption of weak coupling between the two subdomains. Two-and-a-half dimension (2.5D) finite element boundary element (FEM-BEM) is used to analyse the elastodynamic problem. The computation of the re-radiated noise from the vibration of the structure is done with a 2.5D acoustic boundary element method (BEM). The acoustic as well as elastodynamic BEM used in this analysis is based on globally regularized integrals based on singularity subtraction.Peer ReviewedPostprint (published version

Ground-borne vibrations due to railway traffic in urbanized areas: A numerical study about traffic in trench cross-sections

Modern cities require efficient mass transportation systems like subway and railway networks. Due to the lack of available space and also due to environmental concerns, it is usually preferable to use the underground space to construct such kind of infrastructures. In this context, several railway lines run in trench cross-sections in urbanized regions. This option permits to save space, allowing reducing the distance between railway lines and existing buildings. Due to that reduced distance, nearby buildings are exposed to relevant levels of vibrations that can annoys their inhabitants. In the present paper a numerical investigation about the dynamic aspects related with wave propagation due to railway traffic in trench cross-sections is presented. For that purpose, a 2.5D FEM-PML formulation is adopted for the simulation of the main system (track-retaining structure-ground), while the rolling stock is simulated by a multi-body approach. A reference scenario is previously presented, being followed by a parametric study where the influence of the geotechnical properties of the ground was analyzed.This work was financially supported by: Project POCI-01-0145-FEDER-007457 - CONSTRUCT - Institute of R&D in Structures and Construction funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionaliza??o (POCI) - and by national funds through FCT - Fundacao para a Ciencia e a Tecnologia: Project PTDC/ECM-COM/1364/2014 and Individual Grant SFRH/BD/101044/2014.Scopu

Predicting Critical Speed of Railway Tracks Using Artificial Intelligence Algorithms

[Abstract:] Motivated by concerns regarding safety and maintenance, the operational speed of a railway line must remain significantly below the critical speed associated with the track–ground system. Given the large number of track sections within a railway corridor that potentially need to be analyzed, the development of efficient predictive tools is of the utmost importance. Based on that, the problem can be analyzed in a few seconds instead of taking several hours of computational effort, as required by a numerical analysis. In this context, and for the first time, machine learning algorithms, namely artificial neural networks and support vector machine techniques, are applied to this particular issue. For its derivation, a reliable and robust dataset was developed by means of advanced numerical methodologies that were previously experimentally validated. The database is available as supplemental data and may be used by other researchers. Regarding the prediction process, the performance of both models was very satisfactory. From the results achieved, it is possible to conclude that the prediction tool is a novel and reliable approach for an almost instantaneous prediction of critical speed in a high number of track sections.This work was financially supported by: Base Funding (UIDB/04708/2020) and Programmatic Funding (UIDP/04708/2020) of the CONSTRUCT Instituto de I&D em Estruturas e Construções, funded by national funds through the FCT/MCTES (PIDDAC); Project PTDC/ECI-EGC/3352/2021, funded by national funds through FCT/MCTES; European Union’s Horizon 2020 Programme Research and Innovation action under Grant Agreement No 101012456, In2Track3; Grant no. 2022.00898.CEECIND (Scientific Employment Stimulus, 5th Edition) provided by “FCT– Fundação para a Ciência e Tecnologia”.Portugal. Fundação para a Ciência e a Tecnologia (FCT). UIDB/04708/2020Portugal. Fundação para a Ciência e a Tecnologia (FCT). UIDP/04708/2020Portugal. Fundação para a Ciência e a Tecnologia (FCT). PTDC/ECI-EGC/3352/2021Portugal. Fundação para a Ciência e a Tecnologia (FCT). 2022.00898.CEECIN

Empirical, Experimental and Numerical Prediction of Ground-Borne Vibrations Induced by Impact Pile Driving

The automatization of construction activities, which aims to reduce the time and cost of constructions, makes impact pile driving an interesting technique. However, these activities in urban areas can generate excessive vibrations and interfere with people and structures in the vicinity. With that in mind, predicting the expected vibration levels during the project design stage is essential. Different methodologies can be employed in this task, from empirical approaches to detailed and complex numerical formulations. This paper intends to present an overview of the empirical methods and the main physics of the problem from a numerical point of view. The results obtained are then compared with experimental vibration data reported in the literature in order to discuss the adequacy of empirical and numerical methodologies in predicting ground-borne vibrations induced by impact pile driving

A methodology for the calculation of the noise radiated by the rails and the tunnel structure in railway tunnels

In this paper, a robust and fast numerical methodology to compute re-radiated noise in underground railway tunnels is proposed. In this study, the noise analysis does not account for the noise radiation from the train wheels, the rest of the rolling stock structure and the aerodynamic noise. The method is based on decoupled approach, where the acoustic and elastodynamic problems are solved separately on the assumption of weak coupling between the two subdomains. Two-and-a-half dimension (2.5D) finite element boundary element (FEM-BEM) is used to analyse the elastodynamic problem. The computation of the re-radiated noise from the vibration of the structure is done with a 2.5D acoustic boundary element method (BEM). The acoustic as well as elastodynamic BEM used in this analysis is based on globally regularized integrals based on singularity subtraction.Peer Reviewe

A methodology based on sructural finite element Method-Boundary element method and acoustic boundary element method models in 2.5D for the prediction of reradiated noise in Railway-Induced Ground-Borne vibration problems

This work is focused on the analysis of noise and vibration generated in underground railway tunnels due to train traffic. Specifically, an analysis of noise and vibration generated by train passage in an underground simple tunnel in a homogeneous full-space is presented. In this methodology, a two-and-a-half-dimensional coupled finite element and boundary element method (2.5D FEM-BEM) is used to model soil–structure interaction problems. The noise analysis inside the tunnel is performed using a 2.5D acoustic BEM considering a weak coupling. The method of fundamental solutions (MFS) is used to validate the acoustic BEM methodology. The influence of fastener stiffness on vibration and noise characteristic inside a simple tunnel is investigated.Peer ReviewedPostprint (published version

Vibrations Induced by a Low Dynamic Loading on a Driven Pile: Numerical Prediction and Experimental Validation

The present paper addresses the problem of generating and propagating vibrations induced by low-impact loading on a driven pile. In this context, an experimental test site was selected and characterized, where ground-borne vibrations induced by the application of a low dynamic loading on the pile head were measured using accelerometers placed at the ground surface. At the same time, a new numerical approach, based on a coupled FEM-PML (Finite Element Method-Perfectly Matched Layer) formulation, to model the pile–ground system was presented. A very satisfactory agreement was observed between the experimental data collected in these experiments and the prediction performed by the numerical model. The experimental data can be also used by other authors for the experimental validation of their or other prediction models