Mechanism And Application Researches On Fracture Propagation Of Deep-hole Pre-splitting Blasting In Coal Seam

As the object of pre-splitting blasting in coal seam, gas-fillled coal takes on coupling characteristics of gas and solid medium that must be related to exploding cranny extension. Gas existing and moving models rested with crannies in coal seams that are master of coal seam penetrability and gas drainage effect, so the study on cracking mechanism in gas-fillled coal is the theory basis of pre-splitting blasting. Based on the physics and mechanical characteristics of the absorbed gas-coal, the process of desorption, diffuseness and seepage of methane was analyzed, and a math model of flow-solid coupling on gas movement in coal bed was set up. Round blasting hole, the coal breakage action by shock wave was studied; away from shotpoint, the constitutive relation on crack propagation was educed on the basis of detonation and fracture theory respectively. By means of theory analysis, correlative primary explosive parameters effecting blasting efficiency were studied. Adopting ultra-dynamic strain detection technology, a series of experiments on space between blasting and control holes were carried out. Embedding the model of coal cranny extension into DYNA program, correctness and rationality on theoretics deduction were contrasted by computer numerical simulation. The research productions were applied to gas drainage in field, which makes blasting design project optimize evidently in the light of mine practice condition. The research results have important significance for the study of gas drainage of coal seam with low penetrability.