Study On Permeability Improvement And Release Of Pressure Technology Of Deep Hole Pre-splitting Blasting In C1201 Working Face Of ChiYu Coal Mine

Focus on the problem of large gas pressure,poor permeability of coal seam and the difficulty of the gas drainage in the Chiyu Mine C1201 bottom drainage,this paper put forward the deep hole pre-splitting blasting technology to make phenomena better.Throughout the learning of using blasting to relief pressure and increase permeability,by similar simulation test reviewing the effect,at the last,summing-up all the results to optimize the experimental plan in the Chiyu Mine C1201 bottom drainage.Finally,through the investigation of the measured gas extraction data,the application effect of the deep hole pre splitting blasting in the low permeability and high gas coal seam is systematically studied.Firstly,based on the learning of coal seam gas occurrence and flow theory study,we could find the pore structure of coal seam,at the same time,it also showed the way gas transports in this pore structure,concluded that the factors influence the adsorption performance was the coal properties,coal gas its characteristics and external factors.We also summarize the characteristic of coal seam with gas.By learning the current research of overseas and domestic,analysis the mechanism of deep hole pre-splitting blasting,discuss the mechanism of explosive shock wave,stress wave,blasting raw gas,gas pressure and control hole.Here the conclusion:At the moment of blasting,it comes with explosive wave and blasting raw gas,the explosive shock wave destroys the coal because of the huge energy and formulates blasting cavity.The stress wave forces the coal to produce a lot of cranny.Once the stress wave touches the control hole,it will reflect and come into tensile wave.Under the combined action of stress wave,tensile wave,blasting raw gas and gas pressure,the fracture zone becomes bigger and bigger.Secondly,by similarity theory,the paper chooses the similar material and experimental plan according to coal and rock mechanical properties.In order to review the cranny,we use the system of super dynamic strain and NPEI.Here the conclusion:at the moment of blasting,the explosive shock wave compresses the coal,and then,it stretches the coal.The explosive shock wave will desperate with the development of the distance away from blasting hole.At the same time,we can find the electrical resistivity increased hugely because the blasting destroy the channel of current moving,which can reflect the development of the cranny.It also represents the improvement of permeability.It also proves that the radius of loosening area is 4.5m.Finally,according to the measuring data from the Chiyu Mine C1201 bottom drainage,it came with the conclusion that the gas extraction concentration was 1.93?3.2 times than before after the deep hole pre-splitting blasting,and the gas extraction flow was 1.4?2.6 times than before after the deep hole pre-splitting blasting,it also proved that the radius of loosening area is at least 4.5m.All of this show us a reliable way to relief pressure and increase the permeability.