The Monitoring Study Of Bolt Axial Force Based On Optical Fiber Sensor

Bolting has become a major technology to ensure the mine tunnel, slope, the stability of tunnels, while bolting anchoring quality monitoring is an indispensable part, to improve the quality of bolt monitoring and surveillance Assessment of the reliability of real projects to ensure quality and safety anchorage is important.The paper suffered under the bolt shear stress and axial force distribution, introduced one method that sensor pasted on bolt rod to monitor the force of the anchor, but this method has complex production process, installation can not be reused. Under combined uniform axial force characteristics of fiber grating sensing, another bolt force monitoring method is proposed that a sensor mounted on the outer end of the anchor, and the bolt axial force for the fiber grating strain test device.The device consists of cylinders, pressure gauges and FBG sensors. The device is calibrated in the laboratory, suffered the relation between outside the loading device obtained that anchor the axial force F and the light through the grating wavelength shift△λ, according to the data acquisition system collected the wavelength shift bolt axial force can be obtained. Calibration results show that the fiber grating pressure sensor with high sensitivity than the pressure gauge. Force measuring device can be constructed the system using the bolt axial force monitoring, provide experimental evidence to the system used in underground coal mines.The monitoring system has a industrial test in Hongliu Coal Mine of Ningxia, monitoring the bolt axial force in 1121 face Air Lane for 3 months. Analyze the problems of the process of installing and monitoring and propose solutions. Monitoring results show: With the Faces, bolt axial force fluctuation change, when the face advancing to 61.8m bolt axial force when the maximum is 26kN. Give a reference to evaluation of the roadway stability.The monitoring system can be used to monitor the bolt axial force, provide a new method to the anchor force monitoring and the scientific protection to roadway maintenance and safety.