부산대학교 도서관

Rayleigh backscatter fiber optic sensing permits dynamic strains to be measured along an optical fiber with a gauge spacing and temporal resolution sufficient for rail applications. However, this sensing technology is highly sensitive to vibration. A 7.5 m long section of rail was instrumented with optical fiber and strain measurements were recorded during passage of a freight train slowed to 8-11 km/h. This strategy to minimize rail vibration was successful in permitting distributed dynamic rail strains to be measured under freight car loading. The measured rail strains were used to determine the rail shear forces, which were then used with the static wheel loads to determine the rail seat load for 14 consecutive sleepers as the train passed over the field monitoring site. These data were then combined with measurements of dynamic rail displacement captured using digital image correlation to infer the rail seat load-deflection relationships for individual sleepers. These relationships were observed to provide significantly more detailed information about unsupported voids and the sleeper contact stiffnesses than the traditional consideration of the relationship between applied load and rail deflection and highlights how track behavior at a monitored location can be dependent on the conditions and behavior of neighbouring sleeper.Key words: railway, fiber optic sensing, field monitoring, soil-structure interaction.La detection de fibre optique par retrodiffusion de Rayleigh permet de mesurer des deformations dynamiques le long d'une fibre optique avec un espacement entre les jauges et une resolution temporelle suffisante pour les applications ferroviaires. Cependant, cette technologie de detection est tres sensible aux vibrations. Une section de rail de 7,5 m de long a ete instrumentee avec de la fibre optique et des mesures de deformation ont ete enregistrees pendant le passage d'un train de marchandises ralenti a 8-11 km/h. Cette strategie visant a minimiser les vibrations du rail a permis de mesurer les deformations de rails dynamiques distribuees sous chargement de wagons de marchandises. Les deformations de rail mesurees ont ete utilisees pour determiner les forces de cisaillement des rails, qui ont ensuite ete utilisees avec les charges statiques des roues pour determiner la charge sur les appuis de rails de 14 traverses consecutives lorsque le train passait sur le site de surveillance. Ces donnees ont ensuite ete combinees avec des mesures de deplacement de rail dynamique capture en utilisant une correlation d'image numerique pour deduire les relations de charge-deflexion d'appui de rail pour des traverses individuelles. On a observe que ces relations fournissaient des informations beaucoup plus detaillees sur les vides non supportes et les raideurs de contact que la consideration traditionnelle de la relation entre la charge appliquee et la deflexion du rail et soulignaient comment le comportement de la trajectoire pouvait dependre des conditions et du comportement des voisins. [Traduit par la Redaction]Mots-cles : ferroviaire, detection a fibre optique, suivi sur le terrain, interaction sol-structure.
IntroductionRailway track is designed to transfer and distribute the train wheel loads downwards through the rail, sleepers, ballast, and subgrade so that loads in each component are low enough to [...]