Study On The Technology Of Long-hole Pre-splitting Blast In Low-permeability Coal Seams To Increase Permeability

With the depth of coal bed increase in our county, the permeability decrease. Consequentlyit affects the extraction rate and efficiency. The situation of coal mine security situation is moreand more serious. This dissertation used theoretic analysis, numerical simulation, experimentsand field test to study the increase permeability effect and improve the coal seam gas extraction,safety fast excavation. Combining actual measurement in Wuyang Mine of Lu’an Coal MiningGroup, the optimal case of well location and blasting parameter in the cutting face. Aiming to theproblem of the gas difficult drainage in the low air permeability coal seam, we put forward thetechnology of deep-hole presplitting explosion combination of gas pre-drainage in the roadside.First of all, this article describes the background and purport of choosing the thesis andexpatiates the current status of the relevant technology accordingly. The complete stress-strainprocess indicate that fractures enhance permeability significantly. The main fracture of coal issuddenly produce and extension. The permeability increased41.4%~65%in the permeabilitypeaks, with steep increase of permeability.Secondly, the thesis discusses the design plan of the technology of deep-hole presplittingexplosion. The radius of fracture zone and cracked zone can be calculated by theory of blasting.The relation between explosion energy and fracture development is analyzed. The effect of thedeep-hole presplitting explosion on the roadside and the roof is analyzed.Lastly, the changes of the gas concentration and drainage volume before and after blastingwere compared. The gas concentration and drainage volume could be improved, so it can reducemuch drainage time. The damage of roof before and after blasting was changing small. The effectof blasting to the seam roof is little. The blasting can’t affect normal tunnel excavation progress. Through field testing, the deep-hole presplitting explosion can remarkably improve the coalseam permeability. The blasting is applied in coal mine in the result of improving the gasconcentration by40.4%~200%equally with3~5m effective influencing fracture radius. Thetechnology of deep-hole presplitting explosion in low air permeability coal seam is practical.