Study On Evolution Patterns Of Mining-induced Stress And Crack Laws With Long-distance And Multi-seam Mining

Coal resources are irrefragable and continuously produced which leads to the gradual depletion of shallow coal resources, and the mining depth increases year by year. The geological condition of deep mining is more complicated than that of shallow mining, which will arise some new geological problems such as high temperature, high water pressure, high ground pressure, high gas pressure and so on. And coal mines entering the deep mining in our country are generally in a coal seam group mining environment. Coal seam group mining is more difficult than single seam. The mining process is affected by their respective mining and multiple mining. Mining-induced high stress is formatted for the superposition of the stress after multiple mining activities. The stress bearing structure is prone to instability and result in many issues such as difficult supporting in roadway and difficult controlling roof and floor etc. In order to solve the above problems and realize coal and gas mining, based on the occurrence characteristics and mining technology characteristics of A and B groups of Paner mine and laboratory experiment of coal rock mechanics parameters, this paper engages in systemic research on evolution characteristics of stress, fracture and displacement in the process of long distance pressure relief mining of multi-seam with the application of the research methods of similar material simulation, numerical simulation and theoretical arithmetic.The FLAC3D, UDEC2D numerical simulation and 2D similar material simulation models of long distance multi seams are designed through field investigation, data collection and statistical analysis. Evolution characteristics of stress and fracture are analysed after first mining(3 coal), secondary mining(3,6 coal seam), third mining(3,6,7 coal seam) and repeatedly mining(3,6,7,1 coal seam).And stress-fracture evolution law of long distance multi-seam mining is revealed. The evolution model of stress and crack of long distance multi-seam mining are designed based on similar simulation and numerical simulation results. After multi-seam mining, the stress and crack in the surrounding rock mass of coal mining presented superimposed effect. And its effect is much larger than sum of single coal seam mining. The research results for the pressure relief mining of coal seam group of Paner mine provide a theoretical basis and technical guidance. Safe and efficient coal and gas extraction has achieved very favorable conditions especially for 4 coal mining.It also has certain significance for the similar conditions of coal seam group mining design and has certain social efficiency and the engineering application value.