Study On Integrated Outburst Prevention Technology Of "Blasting Injection" And Key Parameters In Mining Face

Coal and gas outburst is one of the biggest obstacles for safe mining in deep high gassy mines.The short pressure relief zone and dry coal seams are the main factors of inducing outburst.Therefore,the blast-injection integrated（BII）technology was proposed.Aiming at the current technical problems of effective hole sealing and explosive misfire,and the limitation of the blasting parameters in the field application does not have generalization.A complete set of integrated equipment of blasting and water injection was developed.The water-seal coupling forward blasting operation method is put forward,which improves the effect of blasting shock wave on coal damage and prolongs the service life of hole sealer.Firstly,theoretical analysis and numerical simulation methods are used.By changing the blasting parameters such as the coupling medium in the hole,blasting method,and blast hole spacing,the dynamic response characteristics of blasting and the blasting gap range are analyzed and verified in a directional and quantitative manner.Secondly,the propagation characteristics and energy distribution of the axial shock wave in the borehole were obtained through laboratory experiments,which further verified the optimization theoretical simulation results.Finally,based on the above conclusions,a water-seal coupling forward blasting operation technical system was established,and technical blasting was carried out on site.The main research conclusions are as follows:（1）The theory verifies the feasibility of the BII technology to eliminate the danger of coal and gas outbursts.Through the establishment of different medium blasting theoretical models,it is found that the blasting pressure of water medium is significantly higher than that of air blasting,and combined with the explosive parameters used in coal mines,it is calculated that the blasting fracture circle radius of air and water medium blasting are 1.3 m and 3.3 m,respectively.And the most significant difference between the two burst pressures is when the non-coupling coefficient is 2-4.It is verified that the hydraulic energy optimizes the blasting effect,increases the range of the fracture zone,and lays a theoretical foundation for further optimization of technical parameters.（2）The ANSYS/LS-DYNA software was used to establish a three-dimensional model,and the key parameters of the blasting technology were studied and optimized in depth.The specific research contents include the blasting differences under the coupling conditions of different water injection ratios in the borehole,the differences of forward and reverse in the borehole,and the optimal blasting hole spacing combined with the parameters of mine explosives.The results show that the parameter combination of water medium coupling,forward initiation and blasthole spacing of 6m can significantly improve the blasting strength and provide good conditions for gas extraction and coal seam water injection.（3）The experimental platform of blasting pressure was set up,and the mechanism of the influence of charging structure on blasting energy was revealed.The numerical simulation and experimental results are compared.The reliability of the simulation is verified.It is found that when the water injection ratio is 100%,the closed blasting is the best when the ratio of length to diameter is 25.（4）The field test was carried out in W_9,10-1416 working face of No.8 Coal Mine of Pingmei.After the blasting,the advanced stress peak of the mining face moved into deep about 6 m,and the damage rate of the hole packer was reduced by about 40%.It is proved that the water seal coupling forward blasting technology system can significantly improve the blasting strength,reduce the impact of shock wave on the hole packer,and reduce the risk of mining face outburst.The research results provide a reference for gas control in mining face of high gas outburst coal seam,which can realize the triple effects of increasing the length of pressure relief zone,expanding the number and range of fractures,and improving the water injection efficiency.There are 50 pictures in this paper,7 tables,and 83 references.