Research On The Evolution Law Of Mining Induced Crack Network In Overburden Rock Strata Of Deep Mining

In this thesis, it was analyzed systematically that evolutionary law of mining induced crack in overburden strata and its movement and failure law in condition of deep mining, by mean of fractal geometry, percolation theory and renormalization group, in combination with physical analogue and numerical simulation. Analog simulation and discrete element method were integratedly used to simulate mining induced crack distribution in overburden strata and its movement and failure, and spot displacement survey was put to use. Based on the anslysis of distribution of mining induced crack, fractal geometry was employed to research fractal characters of mining induced crack and its evolutionary law, and by using of percolation model constructed with percolation theory taking unit crack block as basic lattice point, percolation behaviors of mining induced crack were analyzed, and renormalization lattice model of mining induced crack was established. Research results indicates that, mining induced crack distribution in overburden strata and its evolution have fractal behaivors and are influenced by fault occurrence, coalseam thickness and so on in condition of deep mining, evolution process of mining induced crack shows percolation characters to some extent, and phase transition criticality of evolution process of mining induced crack can be forecasted by renormalization technique, and general regularity of movement and failure of overburden strata in typical deep mining is obtained through similar model test and spot test. Thus a series of the comprehensive research methods are put forward to study the problem of evolution of mining induced crack in the condition of deep mining.