Simualtion Of Coal Seam Deep-hole Presplitting Explosion Using UDEC

The coal mine gas outburst and gas explosion is damaged to the mining production. Deep hole pre-splitting blasting technology is widely used in gas extraction, but its mechanism has not been unified understanding. A dynamic numerical calculation UDEC model was set up by fish. The attenuation law of explosion stress wave in rock is simulated by the discrete element program UDEC. It is observed that numerical modeling results, on the whole, agree well with the calculated results of the deduced theoretical formula. The study shows that it is reasonable to use UDEC to simulate dynamic response of rock subject to explosion.A dynamic numerical calculation coal seam deep-hole presplitting explosion UDEC model was set up by discretizing blocks into deformable triangular finite difference zones with GENERATE command, applying quiet boundaries with BOUNDARY xvisc and BOUNDARY yvisc commands, specifying Rayleigh damping with DAMP command, applying Gaussian source function as stress history on the boundary of smash district. The conclusions as following:1、Numerical calculation shows that the explosion stress wave in coal along with the extension of radial crack and attenuation rule is nonlinear. By curvilinear regression and explosion stress wave in coal accords with exponential decay laws pm=11.25e0.95+90.58e0.1+1.14.Within1m from the center of hole attenuation fastest, in1-4m from the center of hole range attenuation slower, in4m away from the center of hole attenuation speed tends to be stable.2、Coal was completely destroyed in5.11ms. After that, though there is still stress in the body, but without more than the limit of the maximum principal stress intensity,fissure zone maximum radius for3m.3、By computing the optimal hole spacing is6m. When the hole spacing is6m, the fissure in coal seam increases, the gas drainage channels increase, and the permeability of coal seam increases, so coal seam gas extraction rate can be improved.