Bridge scour is soil erosion around the bridge foundation (pier or abutment), which may cause foundation damage. Thus, effective, real-time, reliable, and robust monitoring methods are imperative. This study proposes a distributed fiber optic sensing method based on an ultra-weak fiber Bragg grating (UWFBG) array for scour monitoring and estimation. In this method, most of the optical fiber is installed freely on the surface of piers/abutments in spiral form. The unconstrained optical fiber can deform randomly and easily under flowing water, and the deformation can be collected by the UWFBGs written in the optical fiber. The scour estimation can be realized by analyzing the difference between signals of the optical fiber embedded in the sand and those immersed freely in the water. A series of experiments were designed and carried out to demonstrate the proposed method. The effects of flow velocity and temperature were investigated experimentally. Standard deviation was employed as the scour indicator, because it can indicate the discrete degree of signals. Experimental results show that the proposed method can estimate the scour in real time.

桥梁冲刷是桥梁基础（桥墩或桥台）周围的水土流失，可能造成基础损坏。因此，有效、实时、可靠和稳健的监测方法势在必行。本研究提出了一种基于超弱光纤布拉格光栅 (UWFBG) 阵列的分布式光纤传感方法，用于冲刷监测和估计。在这种方法中，大部分光纤以螺旋形式自由安装在桥墩/桥台的表面上。无约束光纤在流水下容易发生随机变形，变形可以由写入光纤的UWFBGs收集。通过分析嵌入沙子中的光纤和自由浸入水中的光纤信号之间的差异，可以实现冲刷估计。设计并进行了一系列实验来证明所提出的方法。实验研究了流速和温度的影响。标准偏差被用作冲刷指标，因为它可以表示信号的离散程度。实验结果表明，该方法可以实时估计冲刷量。