Multi parameter monitoring technology of borehole for movement and deformation of overlying strata of coal measures

It is an important research content of green,safe and efficient mining of coal resources to accurately obtain the whole process evolution characteristics and failure laws of the overlying strata structure of coal mining. As a passive,high SNR,high precision and long distance deformation monitoring technology,optical fiber sensing test has been applied in the field of mine engineering. Combined with the research status of the movement and deformation of the overlying strata in coal measures and the thinking of its technical development,a multifield and multiparameter monitoring technology system for the full section of borehole is putted forward. Through the analysis of the application of optical fiber sensor testing technology system and several common optical fiber technologies (Fiber braggart grating,FBG,Optical timedomain reflectometer Optical timedomain reflectometer,OTDR,Brillouin optical timedomain reflectometer,BOTDR,Brillouin optical timedomain analysis,BOTDA and Brillouin optical frequency domain analysis,BOFDA) in mine strain monitoring,four kinds of key technical problems existing in the application of optical fiber monitoring technology are discussed. Based on the research of five systems,including sensing system,modulation and demodulation system,signal transmission system,data processing and analysis system,remote monitoring and early warning processing system,a multi field and multi parameter monitoring technology system for the full section of borehole is gradually constructed,including the installation process of sensing unit,selection of borehole backfill materials,joint inversion of multi field parameters and disaster early warning. The dynamic prediction and evaluation of the deformation and failure of rock and soil layer can be realized by using the parameter sensing system of rock and soil layer deformation arranged in underground and surface boreholes to obtain multiple fields and parameters in real time. Combined with the surface vertical borehole monitoring example of a working face in first mining area of Zhaoxian Mine field,Shaanxi Province,the process of full section multifield and multiparameter monitoring of hard roof borehole is studied and discussed,and the multifield response characteristics of rock deformation and its failure structure parameters are revealed. Based on the distribution characteristics of strain field and geoelectric field (resistivity,current) and combined with the geological data of coal measure strata,the advanced abutment pressure,lagging collapse distance,the development law of “two zones” and the evolution characteristics of abscission layer during coal mining are comprehensively analyzed.