Technology Research And Application Of The Hard Rock Loose Blasting In Fully Mechanized Coal Mining Face

In the process of coal mining, complex geological conditions are often encountered, especially when fully mechanized coal mining machine advances to the fault zone, because of the large solid coefficient of fault rock(f>6) and strong clamping effect of deep rock, the loss of the fully mechanized coal mining cutting machine is serious, its service life is reduced, cost is greatly increased, the progress of coal mining is slow, so in this case, consider using blasting method to achieve the purpose of fault. However, due to the limited narrow space of fully mechanized coal mining face, coupled with lots of coal mining equipment and machinery close to the blasting point of fault, general throwing blasting will damage the coal mining equipment and fully mechanized coal mining environment, so in this case, we should choose loose blasting to complete the task of the fault.Therefore, it is an urgent problem to be studied that how to ensure the good blasting effect when the loose blasting method is used in fully mechanized coal mining face of hard rock.Relying on the mining engineering of Luyukou mine 3807 fullymechanized working face, based on the existing theory of rock loose blasting, focusing on the research on the parameters optimization of the hard rock loose blasting in the fully mechanized coal mining face,explore the optimal parameters of hard rock loose blasting, and through the numerical simulation,the analysis and calculation of the stemming length of blasting hole, hole spacing, delayed initiation in the hole and delayed initiation of the hole are carried out,finally, the experimental data collected in the field is verified to the theoretical calculation, the optimal parameters of hard rock loose blasting of Luyukou mine 3807 fully mechanized working face is obtained.Based on the research and analysis, the following conclusions are drawn:1.The effects of dynamic load and static load on the rock are analyzed, and the dynamic characteristics of the rock are discussed in the paper.2.The mechanism and effect size of explosion stress wave and explosion gas on the rock are discussed in detail.3.Through the analysis of rock blasting fragmentation mechanism,the explosive effect range of explosives in rock and the process of blasting damage, theoretical basis for the choice of loose blasting parameters is provided.4.The main factors affecting the loose blasting are analyzed, and theeffective measures to improve the loose blasting effect and control blasting vibration are obtained.5.Using ANSYS/LS-DYNA finite element numerical simulation software,through the numerical simulation of the stemming length of loose blasting,distance between loose blasting hole and the free surface,delayed initiation time of the holes of loose blasting and delayed initiation time in the holes of loose blasting, the hole blasting effect of stemming length of 85 cm is the best, the blasting effect is the best when the distance between the hole and the free surface is 0.5m, delayed initiation time of the loose blasting holes is reasonable, the performance price ratio is the highest when the delayed initiation time of the loose blasting hole is 25 ms are obtained, the reference is provided for the parameters selection of loose blasting engineering practice.6.Through a detailed understanding of the geological and mining conditions of the Luyukou mine 3807 working face, on the basis of the preliminary field investigation and the determination of the related blasting scheme, according to different hole network parameters, five underground loose blasting tests were carried out.Through the numerical simulation results and the effect of the field blasting tests, the blasting parameters are constantly revised and optimized,finally, the optimal parameters of loose blasting scheme are selected.