分布式光纤裂缝传感器特性研究

Experimental Study of Distributed Optical Fiber Sensor for Crack Detection

通过结构裂缝模拟实验和分析,得到了光纤损耗与裂缝宽度之间可靠、实用的半经验理论计算模型。该模型可以使系统对裂缝宽度的理论计算与实验测量误差小于0.02mm,在重点监测区误差少于0.01mm;在大角度情况下(θ≥45°),存在对实际工程应用非常有利的光损耗饱和效应。提出了两光源组合测量系统,能单处确定裂缝的宽度及走向。讨论了光纤网络的布置方案,在可能的开裂破坏区,将光纤埋设成与主体裂缝斜向相交约60°角,可直接布置成立体网络。

A reliable and applicable semi-experience calculation model for structure crack remote measurement has been obtained by analyzing the experiment results of the relation between the optical loss in fiber and the crack width. With the calculation model the fiber optical remote sensing error is less than 0.02 mm compared with the directly measured crack width, and in some key monitored points the error could be even less than 0.01 mm. In the experiment an effect of optical loss saturation in the case of larger fiber-crack cross angles (θ≥45°) has been observed, which will has great applications in the practical engineering projects. To our knowledge, it is the first time that two wavelength optical source has been used for simultaneously monitoring the width and evolution tendency of cracks at a single position. At last, a direct 3 dimension scheme for constructing an embedded optical net-work in the potential split location has been proposed.