大坝裂缝方位对光纤裂缝传感器灵敏性的影响

Effects of Large Dam Crack's Orientation on Sensitivities of Distributed Fiber Optic Crack Sensors

基于混凝土模型试验,对大坝裂缝方位的随机性对基于瑞利散射的光纤裂缝传感灵敏性的影响进行了定量分析,得到了传感光纤在大坝安全监控缝宽控制范围内,与裂缝夹角为20°、30°、45°、60°时的光纤灵敏性与裂缝宽度关系曲线。实验发现裂缝与光纤的方位角每增加15°,则光纤的灵敏性降低一半以上,这表明工程裂缝方位的随机性对光纤裂缝传感的灵敏性具有较大影响。对此影响的力学机理进行了分析,并提出相应的工程对策。

Based on the experiments with concrete samples, the effects of large dam crack orientation＇s randomness on sensitivity of distributed fiber optic crack sensing were analysed quantitatively; The relationships between the sensitivity and crack width of the sensing optic fibers adopted in large dam crack monitoring in China at the crack＇s orientations of 20°, 30°, 45° and 60° relative to the optic fiber within the controlled crack width for large dam safety monitoring and control were obtained; It was found that the angle between the optic fiber and crack increased every 15°, the optic fiber＇s sensitivity reduced more than half, indicating that the crack orientation＇s randomness has great effects on the sensitivity of the fiber optic crack sensing. Finally, the mechanical mechanism of this effect were analyzed, and the corresponding engineering countermeasures were proposed.