A novel fiber Bragg grating (FBG) soil strain sensor

Soil, as an indispensable composition for building foundation materials, plays a significant role in safety and service life of buildings. However, in different regions, soil properties are distinct and complex. With the technology development, studies on soil properties based on soil strain has become important. In this paper, a method of soil strain measurement was proposed based on fiber Bragg grating (FBG) sensing technology. The new FBG soil strain sensor is structurally simple and incorporates clamping devices that are designed to better transfer soil strain. Calibration tests were conducted to verify the performance of the sensor. Then, to satisfy the long-term soil strain monitoring, the sensor's fatigue properties were studied by using an MTS testing machine. Finally, field experiments were carried out, and the experimental results demonstrate that the sensor is sensitive to soil strain and the proposed novel method is effective and reliable for soil strain measurement. In summary, the new FBG soil strain sensor can be embedded in soil for real time measurement of soil strain with good performance and long fatigue life. Benefitting from the FBG technology, many FBG soil strain sensors with different central wave lengths can share one optical fiber, which greatly simplifies the installation and operation when multiple FBG soil strain sensors are deployed. (C) 2019 Elsevier Ltd. All rights reserved.