Application of distributed optical fiber technology for strain and temperature monitoring in mass concrete raft foundations

This is the authors' abstract. We don't add key points for this paper.

• Defined a temperature compensation coefficient for fiber optic sensors using BOTDR. • Optimized sensor layout to improve strain transfer performance in concrete. • Developed a distributed sensing system for simultaneous strain/temperature monitoring. • Demonstrated high practical value for structural health monitoring of mass concrete. Distributed optical fiber sensing (DOFS) technology is promising for health monitoring of mass concrete structures. However, the measurement accuracy is limited by the inherent temperature–strain cross-sensitivity of the sensing mechanism, requiring temperature compensation for the acquired data. Conventional temperature compensation methods, especially the reference fiber method, assume a constant compensation coefficient and ignore its temperature dependence, resulting in measurement errors under high thermal gradients. Furthermore, inappropriate sensor installation approaches often result in poor survival rates and mechanical decoupling under construction conditions. To address these issues, this study develops a dynamic temperature compensation model with a temperature dependent coefficient K, experimentally calibrated for Brillouin optical time domain reflectometry (BOTDR) systems. Additionally, an optimized sensor deployment strategy was developed through comparative experiments on reinforced concrete beams to improve strain transfer efficiency and sensor survivability. The proposed methodology was validated via field monitoring of a mass concrete raft foundation, successfully monitoring the evolution of strain and temperature in critical regions. This study provides a theoretical basis and key technical support for distributed optical fiber monitoring of strain and temperature in mass concrete structures.