基于光纤传感技术的泥石流冲击力测量系统与反演方法

目前水槽实验一般采用压电式压力传感器测量泥石流冲击力,这种传统测量模式的电信号易受电线阻抗效应的影响,且没有考虑测量装置受冲击变形对测量结果所产生的影响。针对以上问题,基于光纤布拉格光栅(Fiber Bragg Grating,FBG)传感技术,设计了悬臂梁式泥石流冲击力测量系统; 基于泥石流的宾汉体模型和受冲击体的本构关系,构建了包含中心波长最大偏移量、结构材料弹性模量和流深的泥石流最大冲击力反演公式。依据测量系统的力-光耦合效应设计水槽实验,开展了7组不同密度(1.8、1.9、2.0 g·cm^-3)的冲击实验工况。结果表明:①数据之间呈现较好的规律性,光纤布拉格光栅中心波长最大偏移量随着密度的增加而增大,同一密度下光纤布拉格光栅中心波长变化过程与泥石流冲击过程相吻合,从而验证了冲击力反演模型和测量系统之间具有良好的适应性; ②冲击力峰值为30.75～74.06 kPa,冲击力系数为0.92～1.95,与泥石流冲击特性相吻合,进而验证了本测量系统在克服传统压电式压力传感器自身缺陷的同时,亦能实现冲击力的稳定可靠测量。

Fiber Sensing Technique Based System to Measure and Invert Debris Flow Impact Force

Flume experiments generally use piezoelectric sensors to measure debris flow impact force. The electrical signal data in the traditional measurement mode are easily affected by the impedance effect of power line. In addition, the device deformation induced by the impact force is not considered, which can influence the measurement result. To address the above issues, a system by integrating cantilever beam and FBG for measuring debris flow impact force was designed. Based on Bingham model of debris flow and the constitutive relation of cantilever beam, the inversion formula for the maximum impact force of debris flow including maximum shift value of central wavelength, elastic modulus of structral materials and flow depth was derived. The flume experiments schemes were designed according to the force-light coupling effect of the measurement system, and the impact experiment cases considering several different densities of debris flow(1.8, 1.9, 2.0 g·cm^-3)were carried out. The results show that: ① These data show good regularity. The maximum shift values of FBG center wavelength are positively correlated with density of debris flow. Under the same density, the FBG center wavelength change process and debris flow impact process have the similar trend, which verifies the good adaptability between the impact force inversion model and the measurement system. ② The maximum impact force ranges from 30.75 to 74.06 kPa, and the impact force coefficient ranges from 0.92 to 1.95, which is consistent with the impact characteristics of debris flow. It is verified that the measurement system can achieve stable and reliable measurement of impact force while overcoming the defects of the traditional piezoelectric sensors.