用低变形传感器监测民用工程结构变形一致性毕业设计外文翻译.docxVIP

Low-coherence deformation sensors for the monitoring of civil-engineering structures D. Inaudia, A. Elamarib, L. Pfluga, N. Gisinb, J. Breguetb, S. Vurpillota “IMAC, Laboratory of Stress Analysis, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland ‘GAP, Group of Applied Physics -Optical Seciion, Geneva University CH-1205 Geneva, Switzerland Rcccivcd 25 January 1993; in revised form 8 March 1994; accepted 25 March 1994 Abstract An optical-fiber deformation sensor with a resolution of 10 pm and an operational range of 60 mm has been realized. The system is based on low-coherence interferometry in standard single-mode telecommunication fibers. It allows the monitoring of large structures over several months without noticeable drift. No continuous measurement is needed and the system is insensitive to variations of the fiber losses. This technique has been applied to the monitoring of a 20 m X5 m X0.5 m, 120 ton concrete slab over six months. It is possible to measure the shrinkage of concrete and its elastic coefficient during pre-straining, giving reproducible results in good agreement with theoretical calculations and measurements performed on small concrete samples. This paper describes the optical arrangement and the procedures used to install optical fibers in concrete. Keywor: Ikformation sensors; Civil-engineering structures 1. Introduction Both the security of civil-engineering works and the law require a periodic monitoring of structures. The methods used for this purpose, such as triangulation, water levels or vibrating strings, are often of tedious application and require one or many specialized operators. This complexity and the resulting costs limit the frequency of the measurements. Furthermore, the spatial resolution is often poor and the observation is usually restricted to the surface of the object. There is thus a real demand for a tool allowing an internal, automatic and perman