| In the process of safe production of coal,coal mines often encounter various mine accidents.The roof accident caused by overburden damage has brought huge economic losses and casualties to the coal mine.In order to prevent such disasters,people in related industries pay great attention to it and pay attention to it.It is urgent to use relevant testing techniques and methods to carry out refined research on the characteristics of overburden damage.This paper introduces the basic principle and test method of overburden damage detection,and uses FLAC3D numerical software to construct a three-dimensional geological model of overburden strata in the stope,and studies the characteristics of overburden deformation and failure during coal seam mining,combined with geoelectric field observation system and related monitoring techniques.The coal surface resistivity value and electrode current change are effectively detected,and the development law of overburden failure in the stope is comprehensively analyzed,which is of great significance for coal mine safety and efficient mining.According to the mechanical test data of the 3-1 coal seam roof rock stratum of a coal mining face in the Mengkeqing mining area of Inner Mongolia,the FLAC3DD numerical model was constructed to simulate the deformation and failure characteristics of the overlying strata in the stope.The numerical simulation results show that during the coal seam mining process,the stress and concentration of the overburden in the stope are formed,and the stress support structure is formed on both sides of the working face and the surrounding rock.The shearing damage of the top and bottom of the working face.The stress state of the overlying strata and the failure mode of the plastic zone in the main site are“saddle-like”distribution,and the development height of the water-conducting fracture zone is 105.9 m.The displacement of overburden rock continues to increase with the coal seam recovery,and the maximum is 0.176 m.The geoelectric field observation system and resistivity CT method were used to measure the failure law of overburden strata during the mining of 3-1 coal seam in a coal mining face in Menkeqing mining area.The results of the resistivity inversion and the electrode current ratio were determined.The development height of the overburden water-fracturing fissure zone is 108m,which is the interface between sandy mudstone and mudstone.The development height of the fault zone is 22m,which is the interface position between fine-grained sandstone and medium-grain sandstone.The influence of the pre-stress on the working face is 60m,and the development range of the fracture zone is 120127m.The average mining height of the 3-1 coal seam is 4.35m,the split-production ratio is 24.6,and the ratio of the mining to the mining is 5.1.The development height of the saddle of the water-conducting fracture zone of the working face is slightly lower than the edge height.Through a comprehensive analysis of numerical simulation and field measurement results.It is judged that the development height of water-conducting fracture zone detected by the two methods is basically the same as that of overburden failure.Thus,the final development height of water-conducting fracture zone is 108 m and the development height of caving zone is 22 m in Jurassic 3-1 coal seam mining.Because the height of water conduction fracture zone obtained by empirical formula is quite different from the measured results,it shows that the formula of"two zones"prescribed for water control has certain limitations and regionality,and can not be fully applied in Menkeqing mining area.At the same time,the crack-height ratio and caving-mining ratio of the measured results can provide a certain reference value for the study of overburden failure development law in Jurassic coal seam mining,and provide a certain basic guarantee for mine safety production,water disaster prevention and protection of coal pillars.Figure[23]Table[5]Reference[98]... |
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