基于光纤光栅传感器的水下盾构隧道健康监测与安全评价

Health Monitoring and Safety Evaluation of Underwater Shield Tunnels Using Fiber Bragg Grating Sensors

为保证水下盾构隧道在施工和运营过程中的结构安全性,依托江苏某过江隧道建设工程,选取最危险、薄弱的典型断面安装光纤光栅传感器,建立隧道结构健康监测系统,实时掌握水下盾构隧道受力变形规律,及时判断隧道结构健康状况。首先,该系统对采集的健康监测数据进行异常数据的识别、剔除和补全等预处理;然后,结合温度、土压力和渗压等外部因素对监测数据进行关联性分析,研究外部因素对隧道结构受力变形的影响规律;最后,以管片收敛变形和钢筋应力为评价指标,对隧道结构安全性进行评价,并通过计算结构安全系数验证结构安全性评价结果。研究结果表明:1)拉依达准则和箱形图法能够有效识别异常数据,且识别的异常数据基本能通过估计邻域法的检验;2)对土压力和渗压分别与钢筋应力进行灰色关联分析,发现钢筋应力受土压力影响较大,管片变形受渗压作用更明显;3)以管片收敛变形和钢筋应力为评价指标,对单环监测断面进行安全性能评价,确定结构安全等级为1级,结构完好。通过钢筋应力推算结构弯矩和轴力,计算最危险管片结构安全系数为4.20,满足规范要求,安全评价结果准确,结构性能安全。

A most dangerous and weak typical cross-section of a river-crossing tunnel in Jiangsu,China,is selected and arranged with fiber Bragg grating sensors.Sequentially,a tunnel structural health monitoring system is established to collect the deformation patterns of underwater shield tunnels in real-time,identifying the health status of tunnel structures.Preprocessing treatments,such as identification,elimination,and completion,are implemented for abnormal data in health monitoring data.Then,association analysis is conducted on monitoring data based on temperature,soil pressure,and water pressure,revealing the influencing patterns of such factors on tunnel structural deformation.Finally,the safety of tunnel structure is evaluated by taking the convergence deformation of segment and steel stress as evaluation indices.The structural safety evaluation results are validated by calculating the structural safety factors.The results reveal the following:(1)PauTa criterion and box plot can identify the abnormal data effectively,and the abnormal data can pass the test of estimation domain method. (2) The grey correlation analysis results of soil pressure and water pressure respectively show that the reinforcement stress is considerably affected by soil pressure, and the deformation of pipe segments is more significantly affected by water pressure. (3 ) The safety performance of a monitoring cross-section is evaluated by taking the convergence deformation of the segment and the stress of the reinforcement as evaluation indices. The evaluation results show that the structural safety is Level 1 with intact structure. The safety factor of the most dangerous segment structure calculated by the bending moment and axial force of the structure is 4.20, demonstrating an accurate evaluation result.