岩体震动波传播光纤光栅监测机理及实验分析

Monitoring Mechanism and Experimental Analysis of Shock Waves Testing in Rock with Fiber Bragg Grating Sensing

为探索煤岩动力灾害新的监测方法,开展了震动波传播光纤光栅监测机理及监测过程的理论与实验研究。针对光纤光栅悬臂梁式加速度传感器,通过理论传感模型得出了震动波作用下的传感方程;以石灰岩板为研究对象,开展了震动波传播光纤光栅传感监测的实验研究,分析了不同条件下的波长变化特征,结果表明,光纤光栅加速度传感器可以较为精确地监测震动波的输入频率,波长变化量与震动波的输入频率、传感器的布设角度等参量有关;当输入频率越靠近传感器的固有频率、传感器与震源连线之间的夹角越小,以及测点距震源越近时,光纤光栅的波长变化量越大,光信号响应特征越明显。以上研究表明,通过光纤光栅加速度传感器可以实现岩体内部不同参数震动波传播的精确测量。研究为探索岩体震动波传播提供了新的监测方法与手段,这对于形成一种更为有效的矿井动力灾害预报预警技术具有重要意义。

To explore a new monitoring method for coal and rock dynamic disasters,the theoretical and experimental research was carried out on monitoring mechanism and process of shock waves testing with fiber Bragg grating(FBG)sensing.For the FBG cantilever acceleration sensor,by the theoretical sensing model,the equation of monitoring shock waves was obtained.Using a limestone plate,the experimental study of shock waves testing with FBG sensing was carried out,and the variation characteristics of wavelength under different conditions were analyzed.The results show that the FBG acceleration sensor can accurately monitor the input frequency of shock waves,and the wavelength variation is related to the input frequency of the waves,the layout angle of sensor and other parameters.When the input frequency is closer to the natural frequency of the sensor,the angle between the sensor and the source line is smaller,and the sensor is closer to the source,the greater the wavelength change of FBG,and the more obvious the response characteristics of the optical signal.The research shows that the accurate measurement of shock waves with different parameters in rock can be realized by FBG acceleration sensor.This study provides new monitoring method and means for shock waves testing in rock,which is of great significance to form an effective method of prediction and early warning for mining dynamic disaster.