为光纤裂缝传感的工程应用提供具体的指导，进行混凝土模型试验。试验针对大坝裂缝方位的随机性对基于瑞利散射的光纤分布式监测能力的影响进行了定量分析，发现裂缝相对于光纤的方位增大时，光纤的复用能力呈现更大幅度的增加，表明工程裂缝方位的随机性对光纤分布式监测能力具有较大影响;对这种影响的机理进行了分析，并提出相应的提高光纤分布式裂缝传感复用能力的技术路径。

For providing the basis of fiber optic crack sensing for engineering monitoring, concrete sample tests were performed. Based on the experimental results，the effects of the crack orientation's randomness on the multiplexing capability of distributed fiber optic concrete dam crack detection
were analysed quantitatively.It is found out that as the angle between the optic fiber and crack increases, the optic fibers multiplexing capability enlarges to a greater degree, indicating that the crack orientations randomness has great effects on the multiplexing capability of fiber optic crack sensing. Finally , the mechanism of this effect was analyzed, and the corresponding technical means of improving the multiplexing capability of distributed fiber optic crack sensing were roposed.