Stiffness Variations on Railway Tracks Over Culvert Underpassings
Total Page：16
File Type：pdf, Size：1020Kb
Stiffness variations on railway tracks over culvert underpassings - A comparison between rigid concrete culverts with flexible steel-soil composite culverts By Dan Sergei Sukuvara Civil and Environmental Engineering Submission date: June 2019 Supervisor: Prof. Steinar Nordal Norwegian University of Science and Technology Department of Civil and Environmental Engineering NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING Project title: Date: Stiffness variations on railway tracks over culvert underpassings 14.06.19 - A comparison between rigid concrete culverts with flexible steel- soil composite culverts Number of pages 86 Author: Dan Sergei Sukuvara Number of appendixes E-mail: [email protected] 3 Degree: Master of Science in Engineering (MSc) Study programme: Geotechnics and geohazards Professor in charge: Steinar Nordal External professional contacts/supervisors: Geir Svanø Employer: Bane NOR Abstract For many years have railway transition zones between embankment and bridge, both in Norway and internationally been described as a problem area where extra maintenance required. It is often thought that these problems relate to a combination of differential settlements and the sudden change in track stiffness, a deterioration loop which leads to an increase in track interaction forces and eventually creates differential settlements as a result. Comprehensive FEM with PLAXIS 2D was used in this thesis to model four railway transition zones in an attempt to quantify the stiffness variations seen over flexible and rigid culverts. The model involves train loads passing over a railway culvert where displacements are studied. From using the principles of plane-strain, it was possible to model the entire problem from skratch by building a culvert, backfilling, building a track and modelling moving train loads. The proce- dure purposed in this thesis was then used to study four specific scenarios of railway transition zones, but also for investigating the behaviour of these culverts. The results from these models suggests that the magnitude of the problem is insignificant as long as certain conditions are met. Data from the norwegian measuring car «ROGER 1000» has also been used for assessing six selected railway culverts were it was investigated if there was any correlation between the apparent stiffness variations at these sites and vertical track deviations measured by the veichle. For the six culvert cases, no clear trend in vertical track deviation over them was found when comparing to the adjecent free track. The general conclusion is that stiffness variations over these culverts are to small to create any obvious deterioration problem seen in vertical track geometry when comparing to a normal track. Keywords: 1. Railway transition zones and culverts 2. FEM using PLAXIS 2D 3. ROGER 1000 measurements 4. Stiffness variations and maintenance I Preferance This Master Thesis has been written as a mandatory closing part of the Master of Science programme, Geotechnics & Geohazards. The thesis make up for 30 out of total 120 credits in the programme. The work behind this thesis was carried out during the spring semester of 2019 at the Norwegian University of Science and Technology (NTNU), Trondheim. The topic for the project was a continuation from the autumn's specialization project regarding railway transition zones in Norway, purposed by Geir Svanø and Juan Barrera from Bane NOR. Trondheim, 14.06.19 Dan Sergei Sukuvara II Acknowledgement During this project I’ve been consulting with several people, but my biggest thanks goes to my main supervisor Prof. Steinar Nordal and Dr. Albert Lau from the road and transport department. Their constant support during this project has been exceptional, Steinar for always making room for discussions and sharing his broad, yet outstanding knowledge. Albert for helping me whenever I was stuck on topics regarding railways. I would’ve never be able to keep such standard on so many broad topics without their constant support through the entire project. I also want to show my gratitude to Prof. Gustav Grimstad for interesting discussions and learning experiences regarding FEM in PLAXIS. His supervision was very helpful whenever I was stuck on parts with the model. A thanks goes to the seniors from Bane NOR, Geir Svanø and Alf-Helge Løhren for providing me with necressary information and sharing their experiences on topics related to railways. I also want to thank Trine-Lise Lorentsen for extracting and organizing ROGER 1000 data for me. Lastly, I want to thank Peder Hembre from ViaCon Norway and Jan Vaslestad from Statens Vegvesen for supporting me with litterature and discussions related to flexible steel-soil composite bridges. Peder provided me with alot of background information on several culverts used as a reference in this thesis, and Jan provided me with litterature and participated in several discussions where he shared his experiences. III Summary Railway transition zones, i.e the transition between embankment and bridge has over many years been reported as a problem area that requires additional maintenance. These problems are often thought to be related to differential settlements but also the sudden change in track stiffness, a deterioration loop which gradually worsens from train traffic as time passes by, which deteriorates the tracks geometry and causes higher rate of wear in all elements of this area. In this project the bridge transition problem was investigated and compared between rigid and flexible steel-soil composite culverts. In Norway, all new bridges expect for flexible ones are instrumented with transition slabs, a short concrete plate which extends out from the bridge a couple of meters into the fill. This is a fixed requirement independent of axle loads, bridge type or train speed. When comparing the transition slab to international solutions, questions arise from its relative short lenght compared 20-30 meter long transition zones seen at other high speed lines. In addition to this questionnaire comes the confusion from flexible steel-soil composite bridges which has no requirement set for the transition zones. From a comprehensive FEM with PLAXIS 2D was it possible model the entire problem in plane-strain from scratch in an attempt to quantify the problem over these culverts. The procedure involves building a culvert, constructing a railway track and modelling moving train loads which was used in the analysis of four specific cases created for this project. The general conclusion is that the irregularities seen at the track over these culverts from the model is relative small compared to a normal track. The pressumed correlation between stiffness variations and increased deterioration rate at transition zones was also investigated with ROGER 1000 data, a measuring car which rutinely registers vertical track deviations among other things for the entire railway network in Norway. In general, no trend were found for the six preselected culverts between the presumed stiffness variations over them and vertical track geometry deviations measured by ROGER 1000, when comparing them to the measurements at the adjecent free track. The conclusion from this project is that the stiffness variations seen at these kind of culverts are relative small as long as certain conditions are met, and there is no direct correlation between stiffness varations, differential settlements and increased deterioration in the transition zones of these culvert underpassings. IV Sammendrag Overgangen mellom bru og fylling («overgangssone») har over mange år blitt beskrevet som et problemområdet der det er et større behov for vedlikehold enn i et vanlig spor. Problemet er ofte tenkt å være relatert til differansesetninger men også stor variasjon i stivhet sett fra jernbanesporet, en ond sirkel som gradvis forværres av togtrafikk ettersom tiden går som vil forårsake geometriske avvik og økende slitasje på sporkomponentene i dette området. I dette prosjektet ble problemet med overgang bru-fylling undersøkt for stive og fleksible samvirke kulverter. I Norge stilles det et minimumskrav til at alle nye bruer med unntak for fleksible stålrør skal instrumenteres med over-gangsplate, en kort betongplate som strekker seg ut fra bruen et par meter inn mot fylling. Dette er et fastsatt krav uavhengig av aksellast, brutype eller toghastighet. Når overgangsplata sammenlignes med internasjonale løsninger stilles det spørsmål til dens relative korte lengde til sammenligning med 20-30 meter lange overgangssoner sett på andre høyhastighets- baner. I tillegg til dette spørsmålet skapes det desto større forvirring til at det ikke er stilt noen krav til overgangssonene for fleksible samvirkekonstruksjoner. Fra en omfattende FEM analyse med PLAXIS 2D var det mulig å modellere hele problemet overgangs- soner i plan-tøyning fra scratch i et forsøk om å tallfeste problemet. Prosedyren omhandler bygging av kulvert, bygging av jernbanespor og modellering av bevegelige toglaster. Denne metodikken ble benyttet for å analysere fire spesifikke scenarioer laget for dette prosjektet. Den generelle konklusjonen etter disse modellene er at de uregelmessighetene (forskjellene) i forskyvning sett på et jernbanespor som følge av disse stivhets-variasjonene er relativt små til sammenligning med et vanlig jernbanespor. Den ofte antatte korrelasjonen mellom stivhetsvariasjoner på et jernbanespor og økt nedbrytningsrate i overgangssonene ble også undersøkt med ROGER 1000 data, målevognen