光纤布拉格光栅在季节冻土路基应变检测中的应用

介绍了现行光纤布拉格光栅（FBG）测试技术的应用领域、传感原理以及常用的封装方式，探索将FBG用于季节冻土路基这种隐蔽工程应变检测中的适应性。主要工作有：（1）基于FBG测试技术的植入梁方法，在传感器布设方面，根据不同测试对象提出了两种封装布设方式：浅置短距离半柔性探测杆和深置长距离半刚性探测杆两种封装布设方式；（2）针对现场测试需要，对电源、光纤传感器、数据采集及分析等整套现场测试系统进行了比较优选；（3）选择两处季节冻土路基作为埋设场地并开展为期1 a的观测。测试结果表明：FBG在-20～30 ℃的温差范围内保证了很高的存活率，所提出并实现的季节冻土路基应变测试系统具有较高的测试灵敏度和可靠性。该套测试系统为隐蔽工程的物理性质指标测试提供了新的技术手段。

Application of fiber Bragg grating sensors to strain detection of seasonally frozen subgrade

This paper describes the applications, principle and common packaging method of existing fiber Bragg grating (FBG) testing technology. The applicability of FBG to strain detection of seasonally frozen subgrade which is a concealed work is explored. The main works are as follows: (1) Based on the method of embedded-beam for the testing technology of FBG, two ways for the packaging and layout of sensors are introduced taking account of the difference of testing objects, namely the shallow-setting semi-flexible feeler rod for short distance and the deep-setting semi-rigid probe for long distance. (2) To meet the need of tests in field, the systems of power supply, fiber optic sensors, data collection and analysis are compared and selected. (3) Two sites of seasonally frozen subgrade are chosen and a one year observation is conducted. The results indicate that FBG has a high survival rate within the temperature range from -20 ℃ to 30 ℃. The system of strain detection for subgrade in seasonally frozen soil regions presented and achieved here has a high testing sensitivity and reliability. The system provides a new technical means for testing physical indices of concealed works.