Dunay - a system for monitoring of activity in the buffer zone of the pipeline

Denis I. Groznov T8 Moscow, Russian Federation  
Andrey V. Leonov T8 Moscow, Russian Federation  
Oleg E. Naniy T8 Moscow, Russian Federation  
Evgeniy T. Nesterov T8 Moscow, Russian Federation  
Vladimir N. Treshchikov T8 Moscow, Russian Federation vt@t8.ru
Monitoring of micro-vibrations of soil using coherent OTDR is one of the most promising ways to monitor activity in the buffer zone of the pipeline. An ordinary optical fiber which is laid along the pipeline is used as the sensor (for example, the dark fiber in a fiber optictelecommunication cable). Movement of people or vehicles, excavation works are causing a vibration of the soil which is transmitted to the cable and is detected by the monitoring system.
Materials and methods
A coherent OTDR is used. A sounding pulse is sent into the fiber at a frequency of 1 ... 2 kHz,and changes in the reflectogram are analyzed. Classification of influences is based on precalibration (by analogy with the recognition of images).
The length of the buffer zone controlled by a single OTDR may reach up to several dozens of kilometers. The system sensitivity to external influences depends on the type of influence, the physical characteristics ofcable (design, depth of installation), and the ground condition. In average, the movement and work of heavy vehicles are reliably detected at a distance of 100 m from thecable, the movement of the truck - up to 10 m, pedestrian movement - directly over the cable.
Systems for monitoring of activity in the buffer zone with the use of coherent OTDR have many advantages, among which are: cost efficiency, hidden installation, high sensitivity, all-weather operation, easy maintenance. With no doubt they will be widely used for tasks of pipelines security and maintenance.
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coherent OTDR pipeline safety security system