Study On Rock Pressure Law Of Large Cutting Height Workface Under Different Mining Velocities

Through the in site measurement in1611(3) working face with mining height of6.0m in ZhangJi Coal Mine for studying rock pressure law of large cutting height workface under different mining velocities, The conclusion:Periodic weighting length and sustainable pressure length extend obviously with the increase of mining rate, advance before workface increase too, appear stress concentration, the side fall roof reduced. Use elastics,basic principle of rock mechanics, deduce the discrimination conditions and load calculation of key stratum on top of stope,guide with the key strata theory, combine with damage mechanics and key stratum research results, analyze cantilever structure moving type of key strata and its influence on ground pressure in1611(3) large mining height workface under different mining velocities. Put forward:when mining rate is slow, cantilever structure move through "short cantilever-voussoir beam" alternately, periodic weighting length,sustainable pressure length become short and nonuniform; when mining rate is quicker, cantilever structure move through "long cantilever" directly., periodic weighting length,sustainable pressure length become short and regular. For simulating the distribution of stress and failure zones in surrounding rock and deflection of key strata of1611(3) workface by changing mining depth, the simulation results Coincide with field measurement. According to the problem of support crushing accidents at the ending stage of large mining height workfaces, based on pressure law of1611(3) workface, firstly, decrease effect of workface form key strata moving by reducing mining velocity,then, stop mining at a proper position before removing, avoid the influence of ground pressure at ending stage of workface,...