Dynamic Strain Detection Using a Fiber Bragg Grating Sensor Array for Geotechnical Applications

摘要

In recent years fiber Bragg gratings have been successfully introduced as sensors for strain, temperature and pressure variations (Δe, ΔT, Δp). Their performance and reliability has been proven in many practical applications including strain monitoring in civil engineering and tunneling, downhole monitoring in oil reservoirs and flow assurance monitoring in pipelines. The gratings have great potential to act as true structurally integrated sensor elements. They can be embedded in typical structural or reinforcing elements of civil and geotechnical buildings. Several methods of interrogation schemes are established depending on the desired accuracy and resolution of the measurement. The most important methods are the linear discriminator (edge filter), the tunable Fabry-Perot filter technique, and several interferometer setups. The objective of this work is to study the feasibility of a compact multi-channel monitoring system based on a Dense Wavelength Division Multiplexing (DWDM) filter module for the detection of dynamic strain signals in rough environments. In our experiments three fiber Bragg grating (FBG) components in x-y-z arrangement were mounted on the surface of a granite prism measuring the resonances of the structure under different kinds of excitation. The versatility of the system's application in geotechnical applications is discussed.