现有的铁路轨道监测主要采用电类传感技术, 易受电磁场、外界环境的影响, 存在着安全的隐患。因此, 采用基于全同弱光纤光栅(wFBG)阵列的铁路轨道应变在线监测技术, 用于实时监测轨道的占用情况。通过有限元模拟仿真设计出能感测铁路应变的传感器结构, 研究了传感器的封装技术。通过检测wFBG波长漂移得到应变信号从而实现高灵敏度应变测量。采用全同wFBG阵列对传感器和系统进行了实验室和现场实验研究。结果表明: 该传感结构可以实现较小的光学损耗, 并且能够保证传感器的灵敏度达到3.4 pm/?滋ε, 线性度达到0.997 82, 迟滞误差达到0.8%。该铁路轨道在线监测系统可以满足铁路运行管理的实际需要。

The existing monitoring technologies of railway tracks mainly use the technologies of electrical sensing. These technologies were easy to be affected by electromagnetic fields and external environments and there were potential security risks. Therefore, the on-line monitoring technology of railway track strain based on an identity weak fiber Bragg grating(wFBG) array was used to monitor the occupancy of the track in the real-time. The sensor′s structure of sensing railway strain was designed by finite element simulation and the encapsulation technology of sensors was studied. The strain signal was obtained by detecting wFBG wavelength shift to achieve highly sensitive strain measurement. The identity wFBG arrays were used to verify this sensor and system in the laboratory and field experiments. The results show that the sensor structure can achieve a smaller optical loss, and can ensure that the sensitivity of the sensor reaches 3.4 pm/με, the linearity reaches 0.997 82, and the hysteresis error reaches 0.8%. The online monitoring system of railway track can meet the actual needs of railway operation and management.