| China is a big producer of coals and the annual production stands first on the world list, and coal industry as foundation industry, has the important status in the national economy development. However, the safe situation of the coal mine is very grim, especially the gas accidents have always been one of the most severe natural disasters and been the NO.1 killer of coal mine safety in china, which our government has a high regard to.In order to control gas accidents efficiently, this article has put forward the task of research on the gas drainage by deep-hole presplitting blast.As a technology difficult problem, deep hole pre-splitting blasting in coal seams with high gas and lower permeability to increase mine gas drainage rate has wide application prospect and great practical importance to prevention of coal and gas outburst and the safety of coal mining production.Using the method that the theoretical analysis and experiment research combined industrial test study, analyzing of the law of gas occurrence and moving, summarizing great deal of related literatures and experiences at home and abroad, as well as integrating the current concrete status with real field data of the experimental mine, this dissertation has put forward the discharging scheme of deep hole pre-splitting blasting and deeply analyzed the effect of industrial experiment, proposing the improved methods, afforded the theoretical foundation and techonological support for pre-splitting blasting discharging gas technical measure was overall applicated in next step.Firstly, analyzing present researches on some subjects referring to this study and coal mine gas hazard theory, the paper has detailedly analyzed the gas flow state in coal body around boreholes based on flow mechanics, blasting dynamics, fracture mechanics for rock, rock mechanics and other theories.At the same time, the mathematical model of the gas pratical flow state in coal body around boreholes was established and stress waves and static pressure theory were applied to entirely analyze and summarize the blasting mechanism and characteristics.Secondly, discussing thoroughly the scheme design of deep hole pre-splitting blasting, especially analyzing and researching detailedly the theory calculation of the radius of empty cavity, the influenced radius of pre-splitting blasting of the crush circle and fracture circle, the style of hole arrangement, charge manners and the determination of the aperture and hole distance, then, taking account of the function of the coal rock damage, the anthor has established theoretical formula for calculating the fracture circle radius on the basis of predecessor.Compared with gas drainage rate of the before and after blasting, the pre-splitting blasting improved the permeability coefficent and drainage rate and quantity in coal seam and reduced discharging time under the same condition.After blasting, the gas was efficiently released, the distribution of stress in the coal body was smooth and the stress concentration band was shifted forward.The released range of coal body was increased, then the risk of coal and gas outbursts was discreased.This technique and measure provides and creates a new method for prevention of coal and gas outbursts in datongyi mine.The problems in test were analyzed and the improvement and solve method were proposed which formed theoretical foundation and practical experience for further research.Finally, utilizing grey system theory as well as combining the advantage and disadvantage of grey prediction model of the grey prediction model and Markov chain prediction model to improves the grey prediction model, the author has structured improvement grey Markov prediction model, with which, the dynamical monitoring is carried out for the the gas flow quantity from boreholes in coal seam after blasting. Applying the grey relational theory, the synthetic evaluation of main factors affecting deep hole pre-splitting blasting effect and optimization choice of blasting program have been carried out.
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