基于光纤传感技术三维地应力传感器研究
发布时间：2019-04-10 11:19
【摘要】：地应力是地球内部岩体属性的重要参数,是监测地震、山体滑坡以及火山活动的重要依据之一。为了实现对地下岩层空间应力大小与方向的有效监测,基于光纤光栅传感技术与平面应力状态测量原理,本文设计并研制出一种监测地下空间应力大小与方向的光纤光栅三维地应力传感器。地应力传感器采用各向异性碳纤维层积复合材料作为载体对光纤光栅进行封装,并将其做成应变传感单元;针对钻孔监测需求,三维地应力传感器整体结构采用圆柱形结构设计,九个应变传感单元组成三组应变花,每组应变花分别放置于一个圆柱形监测探头上。三个探头以一定的空间角度与机械结构组装成一体,形成了对地下空间应力大小与方向监测的光纤光栅三维地应力传感器。地应力传感器中的每个探头分别监测空间中的一个正交平面内的应力状态,将三个正交平面内的最大主应力进行力学矢量合成,最终得到空间中最大主应力的大小与方向。本文以光纤光栅传感理论与应变花测量平面应力状态原理为基础,将两种理论知识相互结合并推导出最大主应变与波长变化之间的关系,给出光纤传感技术应用于地应力测量的理论基础。对应变传感单元进行室内温度标定实验与应力加载实验,温度标定实验结果:在24.1~55℃范围内的温度系数平均值为57.3pm/℃;应力加载实验结果:在0~60Mpa量程内的应力灵敏度为58pm/MPa,应力分辨率为0.172MPa;线性拟合系数为0.99986。将三维地应力传感器埋置于水泥体中并进行应力加载实验,传感器应力加载实验结果:S1、S2探头的测量应力大小平均相对误差分别为16.31%、24.36%,方向误差的平均值分别为1.89°、2.52°;S3探头的绝对误差为0.0068MPa。实际加载应力与传感器测量的应力空间角度误差平均值为1.24°。
[Abstract]:The in-situ stress is an important parameter of the earth's interior rock mass, and one of the important bases for monitoring earthquake, landslide and volcanic activity. In order to effectively monitor the spatial stress magnitude and direction of underground strata, based on the fiber grating sensing technology and the principle of plane stress state measurement, In this paper, a fiber Bragg grating three-dimensional in-situ stress sensor is designed and developed to monitor the magnitude and direction of stress in underground space. The in-situ stress sensor uses anisotropic carbon fiber laminated composite as carrier to encapsulate the fiber grating and make it into a strain sensing unit. According to the requirement of borehole monitoring, the whole structure of three-dimensional in-situ stress sensor is designed with cylindrical structure. Nine strain sensing elements are composed of three groups of strain flowers, each set of strain flowers is placed on a cylindrical monitoring probe. The three probes are assembled with the mechanical structure at a certain spatial angle, and a three-dimensional fiber grating in-situ stress sensor is formed to monitor the magnitude and direction of the stress in the underground space. Each probe in the in-situ stress sensor separately monitors the stress state in an orthogonal plane in space. The maximum principal stress in the three orthogonal planes is combined with mechanical vector, and the magnitude and direction of the maximum principal stress in the space are finally obtained. Based on the theory of fiber grating sensing and the principle of strain pattern measuring plane stress state, the relationship between maximum principal strain and wavelength change is deduced by combining the two theoretical knowledge with each other. The theoretical basis of the application of optical fiber sensing technology in-situ stress measurement is given. The indoor temperature calibration experiment and stress loading experiment of strain sensing unit were carried out. The results of temperature calibration experiment showed that the average temperature coefficient was 57.3pm/ 鈩，
本文编号：2455754
[Abstract]:The in-situ stress is an important parameter of the earth's interior rock mass, and one of the important bases for monitoring earthquake, landslide and volcanic activity. In order to effectively monitor the spatial stress magnitude and direction of underground strata, based on the fiber grating sensing technology and the principle of plane stress state measurement, In this paper, a fiber Bragg grating three-dimensional in-situ stress sensor is designed and developed to monitor the magnitude and direction of stress in underground space. The in-situ stress sensor uses anisotropic carbon fiber laminated composite as carrier to encapsulate the fiber grating and make it into a strain sensing unit. According to the requirement of borehole monitoring, the whole structure of three-dimensional in-situ stress sensor is designed with cylindrical structure. Nine strain sensing elements are composed of three groups of strain flowers, each set of strain flowers is placed on a cylindrical monitoring probe. The three probes are assembled with the mechanical structure at a certain spatial angle, and a three-dimensional fiber grating in-situ stress sensor is formed to monitor the magnitude and direction of the stress in the underground space. Each probe in the in-situ stress sensor separately monitors the stress state in an orthogonal plane in space. The maximum principal stress in the three orthogonal planes is combined with mechanical vector, and the magnitude and direction of the maximum principal stress in the space are finally obtained. Based on the theory of fiber grating sensing and the principle of strain pattern measuring plane stress state, the relationship between maximum principal strain and wavelength change is deduced by combining the two theoretical knowledge with each other. The theoretical basis of the application of optical fiber sensing technology in-situ stress measurement is given. The indoor temperature calibration experiment and stress loading experiment of strain sensing unit were carried out. The results of temperature calibration experiment showed that the average temperature coefficient was 57.3pm/ 鈩，
本文编号：2455754
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