Wavelength Analysis Of Embedded FBG System In Baodian Coal Mine Unconsolidated Strata Through Deep Borehole

Baodian coal belongs to Yanzhou mining area in East Area of China. Mine Shaft of thecoal through the quaternary unconsolidated strata under more complex geological conditions.The shaft frequently destruction had a serious impact on the mine normally produces. Thepredict the shaft deformation method by fiber Bragg grating (FBG) sensor monitoring systemcan meet the long-range distributed and long-term technical requirements of mine monitoring.Therefore, studying the transmission characteristics and installation of the FBG sensor systemhas very important significance.In this paper, the working principle and the constraints of the FBG sensors system, whichwas applied in the monitoring shaft security field, was studied. The grating was analyzed bydiffraction theory and it couble be coupled to back propagation of optical mode. And theresonance condition formula of the FBG was obtained. The relationship between the resonantwavelength and excitation source by differential form was analyed, when the FBG was effectby strain or temperature, which was changing. And a way to avoid cross-sensitivity of strainand temperature was foud. Taylor series expansion of strain response integral formulaindicated that, the maximum error of the linear model can meet the measurementrequirements when strain is0~3000με.Based on theoretical research, designed and installed a FBG sensor monitoring stratumsettlement system according to Baodian coal. The installation processing was studied byanalyzing real-time monitoring data. The FBG sensing systems by a deep borehole withstanda lot of force because of the influence of gravity and grouting. The center wavelength of theFBG sensor deviates from the initial value. The center wavelength decreased after the systemstable but it did not revert to the initial value. Considered temperature compensation, analyzedthe monitoring data after the system stable and predicted of shaft security. Speculated theeasiest destroy position of the shaft.