Application Of Numerical Simulation Analysis To Improving Mining Upper Boundary

Reasonably reducing waterproof coal pillars, improving mining limit，canliberate a lot of dull coal, improve resource recovery, and be great significance forcoal mine production. Large population, coal demand, energy shortage, improvingcoal recovery rate have became an urgent task in China.The development height of the fractured zone is an important factor to improvethe mining upper limit. Usually when the long-wall working face is mined，the roofwill breake and fall down. In the hundreds even thousands of meters deepunderground, the working space has only a few meters. It is because of the limitedmining space that determines the limited damage. In order to further study the fractureheight of different mining height, and improve the upper boundary, the numericalsimulation was used.The working face43down20on Daizhuang mine was taken as a cast study. Basedon the analysis of the hydrogeological characteristics, FLAC3Dsoftware was used tocarry out the numerical simulation analysis of improving the mining upper boundary,the overburden failure law was studied, and the growth height of water-conductingcrack zone was determined. Simulation results shows that the maximum height ofwater flowing fractured zone is about21m after3upcoal seam was mined. When thefaces4321and43down20were mined, the highest upper boundary of plastic zonesreached to35m, leaving about23m clay impermeable layer. Finally based on thehydrogeological and engineering geological conditions, the feasibility of improvingmining upper boundary on the working-face was demonstrated, it proved to befeasible and a reference for the design of waterproof coal pillar was provided.