Research And Application Of Roof Separation Monitoring System Based On Fiber Bragg Grating

China is a big coal producer,We attach great importance to the safe and efficient production of coal enterprises.As the most common accident in coal mining,roof disaster has always threatened the safety of underground personnel and equipment.Therefore,it is particularly important to implement effective monitoring of mine roadway.The traditional electric sensor monitoring system can not meet the needs of underground disaster monitoring during coal mining because of the attenuation of electrical signal transmission and the need for explosion-proof electrical components,which are vulnerable to the impact of moisture and dust environment and accelerate aging.Fiber Bragg grating(FBG)sensing technology provides a safe and reliable technical scheme for coal mine disaster early warning because of its inherent safety,high measurement accuracy,high stability and strong networking ability.This paper focuses on the research and application of roof separation monitoring system based on Fiber Bragg grating.The subject is deeply studied by means of theoretical analysis,numerical calculation,finite element simulation and engineering application.The main research work is as follows:(1)The basic structure and parameters of fiber Bragg grating are introduced,and its basic sensing mechanism under the influence of strain and temperature change is described.The causes for the coupling effect are analyzed,and the implementation of temperature compensation method of unstressed grating is given in detail.Basis the requirements of complex environment and monitoring in coal mine,a new cantilever fiber Bragg grating pressure sensor is designed and studied,and the relationship between the measured pressure and the central wavelength drift is deduced.The thickness of the cantilever beam is determined by finite element analysis.On this basis,through numerical analysis,the effects of various parameters on its sensitivity are discussed.The results show that the sensitivity is higher when the five parameters of fiber Bragg grating effective length,Poisson's ratio,elastic modulus,dowel rod radius and diaphragm thickness are smaller;The greater the diaphragm radius and the length from the fixed end to the force point,the higher the sensitivity.(2)According to the underground geological environment and specific monitoring requirements of coal mine,combined with the characteristics of fiber Bragg grating sensing technology,a passive optical fiber remote intelligent monitoring system for mining roof is constructed by using its related application technology,a host computer interface that can display the on-line monitoring status in real time is developed,and the data visualization is realized.(3)The application of passive optical fiber remote intelligent monitoring system for mining roof in 81404 working face of No.1 Mine of Shanxi Yangmei group is carried out,the monitoring data within 100 m from the working face to the sensor are analyzed,the basic law of roof movement is understood,and the multi parameter real-time monitoring of underground sensors is realized,The feasibility of this kind of system in underground coal mine is verified,which lays a foundation for the domestic coal mine industry to move forward to intelligent mine.