沉降仪是测量路基、桥梁、隧道、边坡等结构物沉降的重要仪器。利用上、下容器相连通结构, 研制了一种水杯式光纤Bragg光栅沉降仪。当沉降发生时, 在压差的作用下, 膜片产生的挠度推动传压杆使等强度悬臂梁的自由端产生同样大小的挠度变化, 使粘贴于等强度悬臂梁表面的光纤Bragg光栅发生拉伸, 进而导致中心波长发生移位, 实验通过检测波长移位可获得沉降量。分析结果显示, 光纤Bragg光栅波长移位对沉降量呈现良好的线性关系, 沉降仪的灵敏度可达15.4pm/cm, 线性度为1.73%FS, 迟滞为0.984%FS, 重复性误差为3.61%FS。

Settlement gauge is an important settlement measuring instrument of subgrade, bridge, tunnel, slope and other structure. The water cup-like fiber Bragg grating settlement gauge is made by applying the up and down containers connected structure. When settlement happens under differential pressure the diaphragm deflection makes that the same deflection change of the free end of the equal strength cantilever is produced by a press-transfer rod. Fiber Bragg grating which is pasted on the cantilever surface is stretched. Center wavelength is shifted. By detecting the wavelength shift of fiber Bragg grating settlement value can be obtained. The experiment result indicates that fiber Bragg grating wavelength varies linearly with settlement, the sensitivity is 15.4pm/cm, the linearity is 1.73% FS, the hysteresis is 0.984%FS and the repeatability error is 3.61% FS.