隧道二次衬砌FBG智能监测与数值模拟

FBG intelligent monitoring and numerical simulation for a tunnel secondary liner

随着公路隧道向长大型方向发展,对其进行长期安全监测是十分重要的工作.光纤布拉格光栅(FBG)传感器作为一种新型的光纤传感器,已被国内外应用于土木工程结构的状态监测和长期监测.在室内进行标定试验,研究FBG的传感特性,得出应变和温度灵敏度系数,证明FBG是一种理想的传感原件,并在某高速公路隧道进行应用.采用三维快速拉格朗日法,获得隧道二次衬砌中应力和位移分布规律,据此提出FBG传感器在隧道内的布设方法、串联粘贴方式及安装工艺;在不同时期对隧道8个断面进行应变监测,并与数值模拟结果对比分析表明,应变与应力和位移具有分布范围的均匀性和分布状态的一致性特点,进一步证明了监测结果的可信性;最后分析应变与降水量随时间的变化特征,评价了隧道的安全状况.

With the expressway tunnel tending to be long and wide, long-term monitoring of the tunnel has become more and more important. Fiber Bragg grating （FBG） sensor is a new tape of optical fiber sensor. Compared with traditional electromotive sensors such as electric resistance strain gage and vibrational chord strain gauge, the FBG sensors have the characteristics of quasi-distributed measurement, long distance, high precision, anti-EMI and durability etc, so this technology has been widely used in status monitoring and long-term measurement of engineering structures. First, the sensitivity coefficients of strain and temperature are obtained by calibration test in laboratory, which proves FBG sensor to be a kind of excellent sensor. Taking a highway tunnel for example, the stress and displacement distribution in secondary liner are obtained using three-dimensional fast Lagrangian analysis of continua （FLAC3D） method. Accordingly the laying scheme, installation technics, series-wound and adhesive method of FBG sensors in tunnel are presented. Second, the strain measurement results of the tunnel＇s eight sections at different period are compared with numerical calculation, which shows the creditability of monitoring data. Finally, the characters of strain and rainfall versus time are analyzed and the safety status of the tunnel is appraised. The research achievements show that the FBG sensor has better stability and higher reliability. Besides,the measurement data are exact and dependable.