Experimental study on a parallel-series connected fiber-optic displacement sensor for landslide monitoring

• Published in: Optics and lasers in engineering 2018-12, Vol.111, p.236-245
• Main Authors: Zheng, Yong, Huang, Da, Zhu, Zheng-wei, Li, Wan-jie
• Format: Article
• Language: English
• Subjects: Deformation behaviors of slopes; Laboratory shear-sliding tests; PSCFODS with bowknot bending modulation; Rock slope failure modes
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2018.08.017

•Sensor design for a parallel-series connected fiber-optic displacement sensor (PSCFODS) with bowknot bending modulation for landslides monitoring is presented.•The application and workability of PSCFODS in monitoring of civil engineering is analyzed and verified by tests.•Four rock slope failure behaviors are investigated and analyzed by PSCFODS. The combined optical fiber transducer (COFT), a newly developed fiber-optic displacement sensor, has proven to be a promising monitoring tool in civil engineering owing to its obvious advantages, such as high initial measurement accuracy, wide measurement range, remote real-time monitoring and convenient installation; however, a limitation is that it cannot realize the potential sliding surface of slopes. In this paper, based on the COFT designed in our previous studies, a parallel-series connected fiber-optic displacement sensor (PSCFODS) with bowknot bending modulation has been developed to determine the location of potential sliding surfaces and monitor the inner deformation in slopes, especially rock slopes. Laboratory shear-sliding tests of the PSCFODS in a self-designed concrete direct shear apparatus with double-shear planes are carried out to test the feasibility and early-warning characteristics of this sensor, while it is monitoring deformation and determining the sliding surface of civil engineering materials or geo-materials. Four different types of test modes corresponding to four rock slope failure modes are considered to investigate the effectiveness and applicability of the PSCFODS in detecting the deformation behaviors of slopes. Results show that the PSCFODS can accurately determine the shear-sliding surface and realize the sliding distance of blocks in four different test modes, which supports its applicability in civil engineering, especially for rock slopes.