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Vibrations generated by rail infrastructure


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Vibrations generated by railway infrastructure. ICR, Ingeniería para el Control del Ruido.

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Vibrations generated by rail infrastructure

  1. 1. Acoustic & Vibration Engineering ServicesVIBRATIONS GENERATED BYRAIL INFRASTRUCTURE
  2. 2. ”Far better an approximate answer to the right question,which is often vague, than answer to the wrong question,which can always be made precise”.John W. TukeyRight questions lead to right answers“I am not bound to swear allegiance to the dogmas of anymaster”.HoraceThe good thing of a problem without an obvious solution is thepleasure in finding it“I support that symbiogenesis is the result of a long timecoexistence and that is main source of evolutionary noveltyin all superior non-bacterian organisms”.Lynn MargulisFluent communication is the key to progress
  3. 3. ICR provides various standardised predictivestudies in the railway sector:• Design of anti-vibrating solutions for railwayinfrastructures.• Prediction of vibration levels for differentrailway track support types and topologies.• Squeal noise prediction.• Noise certification tests in accordancewith the Technical Specification forInteroperability (TSI).• Track roughness measurements (railirregularity) and the characterisation ofthe dynamic behaviour of the track inaccordance with ISO 3095.• Prediction of compression wave generatedby a high-speed train entering a tunnel.• Analysis of the noise and vibrationtransmission paths (ATPA: AdvancedTransfer Path Analysis Method). Thisspecific ICR method allows an improvementin the interior acoustic comfort of a train.• Environmental impact studies for railwayinfrastructures (train, underground andtrack) at the works’ stage (infrastructureconstruction) and at the service stage(infrastructure operation):1. Vibration impact: study of vibrations and their propagation via the site to the sensitive areas.2. Acoustic impact: noise study.Railway experienceIngeniería para el Control del Ruido (ICR) isa company located in Barcelona dedicated tosolving noise and vibrations problems. Foundedin 1995 by professionals with more than 20year of experience in the field of vibro-acoustics,ICR offers recent analysis methods for railways,automotive, wind power, industry and civilengineering sectors.The company’s goal hasalways been to offer the right and most efficientsolution for each vibro-acoustic problem.ICR has taken up a relevant position in theinternational railway sector over the last decadethanks to the trust placed by the main Europeaninfrastructure constructors. The reason behindthis success lies in the working methodologywhich is based on:• Specific forecasting techniques.• Real measurements to minimise theoreticalspeculations.• The airborne and structural noise treatmentof each element going to make up a coach.• Very short response times.• Prices in line with the market.Most of ICR efforts have been focused on R+D,with the objective to develop new predictiveand analysis methods.This company innovativeprofile has allowed ICR totake part in numeroushighly technological projects, both national andinternational. In some cases, these projects werefocused on a technology transfer from ICR tothe main European rolling stock manufacturers.ICR compromise as vibro-acoustic expert is topropose the adequate solution for each problemof noise and vibration.A WORK METHODThe companys goal has always been to offer the right and mostefficient solution for each vibro-acoustic problem.
  4. 4. The environmental impact studies developed atthe railway infrastructure (train, undergroundand tram) are divided into two differentiatedstages:• Vibration control at works’ stage. Theobjective is to control the vibrations whichthe construction and the works may cause tothe acoustic comfort of the neighbourhoodand the integrity of the buildings nearby.The control of these vibrations is carriedout bearing in mind the standards in forceand the demands of the client.• Vibration forecast at service stage. The goalis to analyze the propagation of vibrationsat the site caused by the circulation ofrailway infrastructure on the track.Both studies are developed considering currentregulations and client demands.BACKGROUNDBackgroundOver the last decade the railway sector hasundergone considerable growth worldwideboth in terms of infrastructure investmentand development. This speedy progress in thesector has resulted in an increase in the numberof railways and in the urban and suburban trainfrequency. By contrast, new environmentalcontamination problems have arisen derivingfrom the vibrations caused during the layoutworks’ stage and the service stage with therolling stock in circulation.Anticipating and predicting these vibrations inthe field is one of the aims of ICR to enablethe client to optimise the projected layout andapply the construction solutions required witha view to avoiding vibrations which are harmfulto the neighbourhood and the integrity of thebuildings near the track.Anticipating and predicting vibrations at the site is one of ICR aimsin this field to allow the client to optimise the layout and apply theconstruction solutions required.Graphic results of vibration measurementsduring the construction phase.Vibration prediction at the service stage.
  5. 5. VIBRATION CONTROL AT WORKS STAGEVibration control at works stageDuring the vibration control phase at theworks’ stage (infrastructure construction) ICRpay special attention to the vibrations causedby the construction works, the earthworks orthe tunnellers with a view to examining theirincidence on the acoustic comfort of theneighbourhood and the integrity of the nearbybuildings. These control studies are carried outaccording to the specifications laid down bythe current standards or indicated by the clientwith the goal to evaluate their compliance.The great variety of tools and study methodsavailable at ICR, enables the company to adaptto the client’s needs at any time and proposethe study type which best suits each situation.This is why ICR provides control measurementsuninterruptedly or control measurements on anoccasional basis by sending an expert to thesite.The control measurements carried outuninterruptedly take place for a variable timeperiod in line with the requirements of eachstudy type (e.g.: 1 month, 2 weeks etc.). Thesemeasurements are carried out in accordancewith the specific requirements or standardsof the client at the pre-defined checkpoints.During this time ICR draws up results’ reportsas frequently as suits the characteristics ofeach study or clients necessities.Concurrently, ICR generates control alarms viae-mail or SMS to provide information aboutvibration levels higher than those set initially.In this way the client discovers in real timewhether the works undertaken fall between thelimits defined.Another study alternative is to send an expertto the site where the works are carried out.By means of the appropriate measurementequipment, are carried out personalizedvibration measurements following thespecifications indicated by the standards orthe client. This study type allows to obtainan immediate feedback and greater flexibilitywhen defining the checkpoints thanks to thepresence of a technician on site.ICR vast experience in this field and theavailability of a multitude of vibrationmeasurements methods and tools enablesthe company to offer very competitive pricesadapted to the client daily reality.ICR provides vibration controlstudies at the works’ stage atvery competitive prices adaptedto the client daily reality.Study of vibration to assess the integrity of the nearby buildings.
  6. 6. Stage 2: excitation characterisationAt this stage ICR is aiming to characterise thesource of vibration by means of measurementson the surface, on the subsoil of the site to bestudied or by means of numerical simulations.Stage 3: determination of the site propagationcharacteristicsICR offers two study alternatives:1. SASW (Spectral Analysis of SurfaceWaves): measurement of the dynamiccharacteristics of the various site layerstages for subsequent modelling basedon the numerical methods of and theinfrastructure to be set up thereat.2. The empirical method: measurement ofattenuation as regards the propagation ofvibrations from the railway infrastructure tothe predefined sensitive points.Vibration prediction at theservice stageIn studies about the vibrational level generatedby the circulation of rolling stock, ICR carriesout several measurements and simulationswith the objective to predict vibrations beforedefining the layout or once defined.The aim is to apply the constructionmodifications required to comply with thestandards in force. ICR thus controls the sitevibrations from the track to the critical zones.The vibration propagation studies developed onthe site are divided into four main stages:• Stage 1: preliminary site study.• Stage 2: characterisation of theexcitations.• Stage 3: determination of the sitepropagation characteristics.• Stage 4: calculation layout as a whole.Stage 1: preliminary site studyDuring the preparatory stage ICR identifies thesensitive points and defines the nuisance limitsin conjuction with the client.For the identification of the sensitive trackzones, ICR divides and categorises the layoutinto various zone types in line with the presenceof sensitive buildings and dwellings near thefuture track.The definition of the nuisance criteria iscarried out in conjunction with the client basedon a study of the risk standards for buildingintegrity, vibration comfort or the limits ofhuman perception.VIBRATION PREDICTION AT THE SERVICE STAGERolling stock at the service stage.The first study allows defining the dynamiccharacteristics of the site and the secondmeasures the propagation of waves via the site.
  7. 7. VIBRATION PREDICTION AT THE SERVICE STAGE1. SASW methodThe SASW method (Spectral Analysis of SurfaceWaves) is a vibrational analysis technique whichallows the dynamic characteristics of the siteto be identified in line with measurements atthe surface and the static physical parameters(taken from the site geotechnical study). Theparameters obtained by this method determinethe dynamic behaviour of the ground andthus enable to predict the propagation of thevibrations on the site and their incidence on thenearby structures.By quantifying all these parameters it canbe draw up a numerical model to predict thepropagation of the vibrations at the site:• Finite Element Modelling (FEM).• Boundary Element Modelling (BEM).• Rayleigh’s analytical propagation models.Excitation at one point and vibration response measurements at various points (surface wave).What does it calculates?Originally,themethodwasdesignedto determineonly the elastic modulus of the different sitelayers but the separate damping evaluation wassubsequently added. Consequently, the SASWallows the simultaneous determination of theelastic modulus and the coupled damping.SASW technology determines the shear wavepropagation speed and the associated dampingfor each of the layers impacting propagation.Concurrently, is used the Nakamura method,which allows the determination of the depthrequired for the numerical model. The numberof layers to be studied, in other words, the sitedepth, will depend on the frequency range to beborne in mind in the future model.How does it works?Vibration studies using the SASW method arecarried out by measuring the accelerations in avertical direction at various points distributedalong a straight line.The excitation source is sited on the sameline. Finally, the propagation speed profile isobtained in line with the site depth.The SASW method allows theidentification of the dynamiccharacteristics of the site.Source of impactMultichannel FTaccelerometersFrequency
  8. 8. where:Lv: vibration level at a sensitive point.LF: force applied by the train at a crossing point.TM: mobility transfer function of the linearsource from the tracks to the sensitive point.This function expresses the ratio between theentry force at the site and the vibration at thesensitive point.Cb: adjustments to take into account theinteraction between the site and the buildingsand the attenuation or amplification of thevibration amplitudes propagated through thebuildings.To obtain the real force applied by the circulationof the train, ICR provides two possible studymethods:• Simulations with a model of the train andusing the ICR data base on rolling stock.• Measurements with rolling stock with thesame or similar characteristics.VIBRATION PREDICTION AT THE SERVICE STAGE2. Empirical methodThe empirical method, based on the FTA manual(US Federal Transit Administration) about thenoise and vibration environmental impact studyis a vibrational analysis methodology whichallows a site to be characterised in purelyexperimental way. In other words, it allows toknow propagation of the direct and indirectvibrations on the site when a force is applied ata given checkpoint.The empirical method is based on carrying outmobility measurements to predict vibrationpropagation from the point where the futurevibration source will be located (the railwayinfrastructure) to the checkpoint. The force isapplied at the same point where the railway isexpected to pass.This work procedure allows:• Data to be obtained about the vibrationpropagation from the track to the sensitivepoints.• When the number of sensitive points tobe studied is low and the sitings are easilyidentifiable, this is an economical solution.How does it work?Method operation is expressed by means of thefollowing formula:CbLFImpedance measurement (f/v)infraestructure (hammer orcalibrated mass).A : acceleration in the track.Lv = LF + TM+ Cb1Study of vibration by empirical method.A: acceleration in the building.
  9. 9. Stage 4: calculation layout as a wholeAt the final stage of the study it is desired:• To estimate, through calculation, thevibrational levels on the layout as a whole.• To provide recommendations about the anti-vibrating support system to be installed atthe critical areas.• To minimise the length of the anti-vibratingsupports’ installations in the layout asa whole, respecting the nuisance levelsdefined at stage 1.VIBRATION PREDICTION AT THE SERVICE STAGETo this end the vibrational levels will beestimated at the base of the buildings and intheir interior based on:• The source of vibration (rolling stock)characterized at stage 2.• The type of supports on the track assembly.• The characteristics of the vibrationpropagation on the layout.Stage 3: determinination of the sitepropagation characteristics.Stage 2: characterization of excitations.Vibratory sourceStage 1: identification of the sensitive areas.Stage 4: calculation layout as a whole.Study of vibration during the service stage.accelerometers
  10. 10. EXPERIENCEControl and prediction of vibrations in rail infrastructure projects• Vibration control generated by the works at Sagrera on the AVE (high-speed train) stretch.Acciona Infraestructuras.• Vibration control produced inside Farmahispania, S.A. factory because of Ferrovial Agroman,S.A. works on the AVE stretch in Montmeló.• Control and monitoring of the vibrational levels inside an industry generated by the AVE worksat the industrial estate Pla sota el Molí in Barcelona. Confidential client.• Vibrational levels control at line 9 of Barcelona underground works. GEOCAT, Gestió de ProjectesS.A.• Study of vibration on a stretch of the AVE (high-speed train) line Valladolid - Burgos in Contreras(Burgos). Ineco Tifsa.• Study of vibration during the works on line 9 of the Barcelona underground. Entorn S.A.,Enginyeria i Serveis.• Study of vibration on line 9 of the Barcelona underground. UTE Gorg.• Weekly control of the vibrations generated by a tunneller on stretch 3 of line 9 of the Barcelonaunderground. Entorn S.A., Enginyeria i Serveis.• Acoustic impact study caused by the passing of the high-speed train (AVE) through theGuadarrama mountain range (Segovia - Soto del Real stretch). Forecast noise levels, pressurepulse at tunnel entry, acoustic impact of the tunnel and track construction works and proposalof solutions. Inimasa.• Acoustic impact study due to the vibrations generated by the circulation of the train nearNorControl industrial plant premises in Tarragona.• Environmental impact study due to a new tram system in the Camp de Tarragona. AudingIntraesa.• Analysis of vibration generated by the circulation of AVE in the vicinity of the future Borgesthermosolar plant and development of a predictive model by Finite Element Modelling (FEM).Abantia and Comsa Emte.
  11. 11. Other projects of control and prediction of vibrations• Vibration measurements at the base of the facade of a dwelling near the client works for a 5-dayperiod. Barcelona. ACSA Sorigué• Occasional control of the vibrational level caused by site drilling at a works located in front ofIndustria Indukern in Prat de Llobregat, Barcelona. Paymacotas.• Vibration measurements in the subsoil and forecast environmental impact by means of vibrationpropagation model and calculation of the vibrating environmental impact at the Montfloriteairport works. Project ZIMA-041189-ES with award no.041190. Ineco.• ALBA del Vallès synchrotron project: tests and vibration prediction at the site using the SASWmethod and Finite Elements Modelling (FEM) to determine the structure required to install theCritical Slab and comply with the vibrational specifications. Determination of the site constantsfor drawing up a numerical model capable of foreseeing the behaviour of the critical zonecompared with the site vibrations. ALBA del Vallès synchrotron Project, Máster Ingeniería S.A.EXPERIENCE
  12. 12. Berruguete, 52. (Vila Olímpica Vall d’Hebron)08035 Barcelona. España - Tel/Fax. +34 93 428 63 39E-mail: icr@icrsl.comwww.icrsl.comIngeniería para el Control del RuidoI RC