基于超弱光纤光栅阵列的地表位移监测方法

Ground surface displacement monitoring method based on ultra-weak fiber Bragg grating array

为了满足采煤沉陷区地表位移精准监测的需要,提出1种基于超弱光纤光栅(uwFBG)阵列的浅层土体位移监测方法。设计1种标距为4 m的uwFBG应变光缆并对其进行适用性分析,该光缆应变灵敏度为1.14 pm/με,迟滞性实验误差小于0.1%。结合自主开发的uwFBG解调装置,构建uwFBG的位移自动化监测系统,并应用于重庆市北碚区天府镇某采煤沉陷区的监测。研究结果表明:浅层土体经过自然沉降和温差补偿后,关键区域在2个月内的累计位移变化约为2 mm,与监测点GNSS(全球导航卫星系统)测量结果吻合,验证了超弱光栅阵列地表位移监测方法的可行性。

In order to meet the needs of accurate monitoring of ground surface displacement in coal mining subsidence area,a shallow soil displacement monitoring method based on ultra-weak fiber Bragg grating(uwFBG)array is proposed.A uwFBG strain gauge fiber optic cable with a standard distance of 4 m is designed,and its applicability is analyzed.The strain sensitivity of the cable is 1.14 pm/μεand the experimental error of hysteresis is less than 0.1%.Combined with the self-developed uwFBG demodulation device,an automated monitoring system for uwFBG displacement was constructed and applied to the monitoring of a coal mining subsidence area in Tianfu Town,Beibei District,Chongqing.The results show that after natural settlement and temperature difference compensation of the shallow soil,the accumulated displacement change in the key area is about 2 mm within 2 months,which matches with the GNSS(Global Navigation Satellite System)measurement results at the monitoring point and verifies the feasibility of the ultra-weak grating array surface displacement monitoring method.