Low modulus polymer packaged optical fiber sensor for macrocrack monitoring in ice structures of cold regions

Abstract

Ice structures provide load-bearing capability for energy exploitation and transportation in cold regions. Meanwhile, staff and facilities take a risk due to large amounts of distributed macrocracks in ice roads, ice bridges, and ice platforms. It is critical to monitor macrocracks for detecting and understanding the fracture process under such a harsh environment. Aiming to obtain real-time, long-term, and quantitative crack opening information for ice structures, this paper presents a feasibility study on monitoring macrocracks with a low modulus polymer packaged optical fiber sensor. Brillouin optical time-domain analysis-based sensing technology is utilized for the distributed strain measurement. According to in situ monitoring requirements, a type of silicone rubber material with appropriate mechanical properties is selected to fabricate the sensor. On this basis, a strain transfer analysis on the packaged and embedded sensor is carried out to derive the relation between the optical measurement and the increment of the crack width. The prototypes have been evaluated by demonstration tests on a tensile device and an ice road model. The experimental results show the sensor can survive in a cold environment and under the large strain resulting from the macrocrack opening. These measured data agree well with the linear calibration. The macrocracks opening in large-scale ice structures can be characterized based on the optical sensor.