Study On Theory And Technology Of Coal Gangue Backfill Strip Mining And Strata Control

At the present, the "under three" coal resources become the only recycling resource for some coals. At the same time, that also leads to serious environment question and social question. The roots of the problem are the open air emissions of gangue and the sedimentation of goaf. In order to solve the serious problem which resulted by coal mining, we should pay more attention to the green mining technology. The core of that technology is the backfill mining with gangue.The research background of this paper is the coal mining by filling the gangue into the tunnel at Xiaonan Coal Mine of Tiefa Caol Mining Company Limited. According to some theories, such as coal mining, theory of elasticity, rockmass Mechanics, surveying course and mining subsidence, and some research methods, for example theoretical analysis, laboratory experiments, numerical simulation and industrial field test, the researches about protecting coal pillar during backfill strip mining with gangue in tunnel were carried out. According to study the limiting equilibrium stress of prearranged pillars, width of yielding zone, the bearing mechanism of filling body and the deforming and breaking mechanism of roof, the stability mechanism dual bearing structure, the prediction formula of roof convergence and the failure criterion of roof and the calculation method of alley mined width were putted forward and analyzed. The filling coal gangues and coal rock samples were collected from Xiaonan Coal Mine. The compression deformation device was designed, which could measure lateral stress. The tests, including compression deformation laws, lateral stress deformation, stress-strain deformation of different graded coal gangues, were carried out. And lateral force measurement method was putted out. Through experimental study, it is founded that the grain size and graduation have an impact on the filling body structure. On the basis of the above researches, the width of coal pillars and alley mined were calculated theoretically. And five kinds of filling mining plans were putted forward. Different mining schemes were simulated with FLAC3D, and study overlying strata and the control effect of ground surface. On the basis of the determined mining method, the process and technology of the backfill mining with gangue in tunnel were studied. The gangue filling device used underground and the turn gangue equipment were developed. The achievements have been applied to the E1S-725working face. Studies show that the initial filling ratio and gangue mechanical properties have effect on the control of overlying strata movement and the initial deformation of roadway. The last, the surface deformation after backfill strip mining was evaluated.Taking Xiaonan Coal Mine as the research object, a method was putted to measure lateral pressure during filling. In the process of compression, all the coal gangues experienced compacted—roken—econsolidated. During the process, the coal gangues gradually lost their bulk property, and could be equivalent to continuum. The width of coal pillars and alley mined are all5m. The surface deformation is small after backfill strip mining. The damage grade of the buildings in the study area is I. Through studying on theory and technology of coal gangue backfill strip mining strata control, the protective coal pillars of Xiaonan Coal Mining industrial square were safely and effectively mined. The study provides a reference basis for mining "under three" coal resources. And also provides research basis for further studying this problem.