相似材料中光纤传感检测特性分析

Transmission Character Analysis of Fiber Optical Sensing in Similar Material of Simulation Experiments

为了解决相似材料模拟实验中的变形检测问题,基于光时域反射技术和光纤光栅传感技术,提出了在模拟实验中采用裸露光纤、一定结构光纤及光纤Bragg光栅作为传感器进行变形检测的方法,研究并分析了以上类型光纤传感器在1.2,2 m平面应力模型中随着相似材料变形的传输特性.结果表明:裸露光纤不易形成微弯;自制蛇形微弯光纤传感器可以较为准确地捕捉到材料内部的变形和破坏的信息;光纤Bragg光栅可以感知相似材料的应力变化.利用光时域反射技术检测时要采取措施增大岩层垮落过程中的光纤损耗,可进行较大变形测试;利用光纤Bragg光栅时要考虑波长的动态范围,可进行小变形及破坏过程测试.

To test the deformation of similar material in simulation experiments, the testing method was presented with naked or certain structure fiber, or fiber Bragg grating（FBG） embedded in rock layers of models based on optical time domain reflectometer（OTDR） and optical fiber grating sensing technology. The transmission characters of these sensors with the similar material deformation in 1.2 m and 2.0 m plane stress models were studied. The results show that micro-bending can＇t be formed easily in naked fiber. The snakelike micro-bending optical fiber sensor can obtain the information of rock damage and collapse exactly, and the fiber Bragg grating can detect the stress change. Some measures must be taken to increase the fiber loss along it when using OTDR, which can test big deformation. The dynamic range of wavelength drifts should be considered when using fiber Bragg grating, which can detect small deformation and collapse of rock.