The hidden nature of subgrades makes the effective monitoring of their deformation very difficult. This paper addresses this issue by proposing the use of fiber Bragg grating (FBG) sensing technology. Here, an FBG is encapsulated within a monitoring tube formed from a polyvinyl chloride tube, and one end of the monitoring tube is fixed perpendicular to a concrete column, forming a cantilever beam monitoring system. The deformation is assessed according to the theoretical relationship between the horizontal strain on the FBG embedded in the monitoring tube and the vertical displacement of the cantilever beam. Then, the relationship between the variation in the wavelength of light reflected by the encapsulated FBG and the temperature and horizontal strain is obtained on this basis by calibration experiments. The monitoring tubes are buried at a proscribed depth below the top surface of the subgrade, which facilitates the monitoring of the deformation and temperature of the subgrade at different stages of construction through the collection of FBG wavelength data during different periods, such as after embedding the monitoring tubes, the completion of the test road surface, and during the period of operation. The proposed technology is verified by employing the system to monitor the instantaneous maximum deformation and permanent deformation of a subgrade under dynamic loads. The monitoring results demonstrate that the instantaneous maximum deformation values of the subgrade at 0.25 m and 0.5 m below the surface are 695.40 μm and 574.02 μm, respectively, and the corresponding permanent deformation values are 53.00 μm and 41.54 μm, respectively. The FBG sensor system is thereby verified to provide a reliable method for conducting long-term continuous, accurate, and efficient subgrade deformation and temperature monitoring.

中文翻译：

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使用光纤布拉格光栅传感技术的路基永久变形和温度监测

路基的隐藏性质使得对其变形进行有效监控非常困难。本文通过提出使用光纤布拉格光栅（FBG）传感技术来解决此问题。在此，FBG被封装在由聚氯乙烯管形成的监测管内，并且监测管的一端垂直于混凝土柱固定，从而形成悬臂梁监测系统。根据嵌入在监控管中的FBG上的水平应变与悬臂梁的垂直位移之间的理论关系来评估变形。然后，在此基础上通过校准实验获得了被封装的FBG反射的光的波长变化与温度和水平应变之间的关系。监测管埋在路基顶面下方的规定深度处，这有助于通过在不同时期（例如在埋入管道后）收集FBG波长数据，在施工的不同阶段监测路基的变形和温度。监测管，测试路面的完成情况以及运行期间。通过使用该系统监控动态荷载下路基的瞬时最大变形和永久变形，对所提出的技术进行了验证。监测结果表明，在地表以下0.25 m和0.5 m处，路基的瞬时最大变形值为695.40。通过在不同时期收集FBG波长数据，例如在埋入监测管之后，测试路面的完成以及运营期间，可以方便地监测路基在不同施工阶段的变形和温度。 。通过使用该系统监控动态荷载下路基的瞬时最大变形和永久变形，对所提出的技术进行了验证。监测结果表明，在地表以下0.25 m和0.5 m处，路基的瞬时最大变形值为695.40。通过在不同时期收集FBG波长数据，例如在埋入监测管之后，测试路面的完成以及运营期间，可以方便地监测路基在不同施工阶段的变形和温度。 。通过使用该系统监控动态荷载下路基的瞬时最大变形和永久变形，对所提出的技术进行了验证。监测结果表明，在地表以下0.25 m和0.5 m处，路基的瞬时最大变形值为695.40。并在运营期间。通过使用该系统监控动态荷载下路基的瞬时最大变形和永久变形，对所提出的技术进行了验证。监测结果表明，在地表以下0.25 m和0.5 m处，路基的瞬时最大变形值为695.40。并在运营期间。通过使用该系统监控动态荷载下路基的瞬时最大变形和永久变形，对所提出的技术进行了验证。监测结果表明，在地表以下0.25 m和0.5 m处，路基的瞬时最大变形值为695.40。 μ m和574.02  μ分别米，和相应的永久变形值是53.00  μ m和41.54  μ分别米。从而对FBG传感器系统进行了验证，从而为进行长期连续，准确，有效的路基变形和温度监测提供了可靠的方法。