Large structures pose a significant risk to lives and property around them in case they fail. Continuous monitoring and preventative maintenance are therefore critical. Using embedded fiber-optic sensing cables, infrastructure operators not only detect changes on the surface, but also quickly localize anomalies deep inside a structure – critical information for targeted preventative maintenance and repair
Shielded strain sensor cables are mounted both on the surface and embedded in structures to register the slightest of shifts. Pre-strained cables enable the detection of swelling or shortening, and vibration-sensitive cables are used to detect micro-cracks when they arise.
Brillouin and Rayleigh-based systems are utilized for infrastructure monitoring applications. Since structural changes are long-term and don’t generally require 24/7 monitoring, mobile measurement systems can be used across multiple sites to maximize utilization and minimize cost. It’s best to equip monitored infrastructure from the beginning, during construction with the right sensor cables. Retrofit installation is possible but limited to surface monitoring.
Brillouin test equipment measures the light frequency shift of side-bands and transforms this into a strain value. Current systems enable detection and measurement down to a few Micro-Strain (micro-meters per meter).
In order to increase adhesion between the sensor and structure, we offer strain cables with a textured surface. Increasingly, multi-function “hybrid” cables are deployed to detect motion as well as sound and vibration.
Depending on the application, strain sensing cables are mounted either directly on the pipe to be monitored or buried in the ground a few meters from the pipeline. Acoustic and temperature-sensing cables are utilised to monitor leakage along oil, gas, steam and water pipes. Incidents are localized quickly to within a few meters.
Bridge and building structural integrity can decline slowly over time, or quickly due to unexpected events like earthquakes, accidents or weather events. With Solifos’ distributed fiber-optic cables, slow changes can be continuously monitored over time. And, in the case of unexpected events, a comparison of before and after performance is done.
In the most technologically advanced countries large buildings are monitored for their long-term stability. In particular, a shift in their foundations needs to be detected early in order to take corrective actions. Strain sensing fiber optic cables are attached directly to foundation pilings for this purpose. External access points simplify periodic measurement of before and after parameters.
Dams and levees are at risk not just from movement but also earthquakes and moisture in the structure. Heatable sensor cables are used for early detection of seepage and moisture in these structures. In combination with a strain sensing cable, Brillouin interrogators can measure both properties at once.