基于光纤光栅技术的海底沉管隧道管段应变研究

Study of sections strain of undersea immersed tube tunnel based on optical fiber grating technology

采用光纤光栅传感器(FBG)对浙江省某海底沉管隧道工程的管节应变进行监测。对传感器型号选择、安装方案及现场安装情况进行了介绍,对实测数据进行分析,研究了各截面测点实测应变值随时间的变化规律以及潮汐荷载对监测结果的影响。根据修正模型对管段应变进行了理论计算,将应变实测值与理论值进行了对比分析。研究结果表明,管段应变在施工结束一年后基本达到稳定,应变随时间变化规律与管段所处位置和两端接头形式有关;潮汐荷载对管段应变影响在0.8%~12%范围内,且与接头形式相关,当管段两端为柔性接头时应变的变化规律与潮汐水位呈现很强相关性,若为刚性接头则相关性不明显;计算得到的管段应变理论值与实测值较为接近,具有一定可靠性。

The strain of pipe section of the immersed tunnel engineering in Zhejiang province is monitored by the fiber grating sensor. The sensor type selection, installation and on-site installation scheme are introduced. The testing data is analyzed and the section measured strain values of the measuring-point changing with time and the influence of tidal load on monitoring results are studied. The measured strain values are compared with the theoretical value according to the modified model for the theoretical calculation of the pipe strain. The results show that pipe strain stabled basically after the end of the year in the construction; and the strain regularity with time is related to the pipe location and the pipe ends joint; the tidal load impacts on pipe strain within the range of 0.8%-12%, and closely related to the joint form; when both ends of the pipe sections are flexible joints, the strain regularity and the tide level showing a strong correlation; correlation is not obvious when it is rigid joints; pipe strain theory calculated and measured values are close, with some reliability.