| In the structure of China’s energy,coal occupies a relatively high proportion and has been the main energy source for a long time.However,coal mine accidents seriously restrict the development of the coal industry.With the continuous progress of science and technology,the death rate of one million tons of coal mines in China has been continuously reduced.However,with the continuous increase of coal mining depth,the proportion of coal seams with high gas and low permeability has been significantly increased,which aggravates the difficulty of gas extraction in coal mines and goes against the safety production of coal mines.In order to improve the effect of gas extraction and ensure production safety,anti-reflection treatment of coal seam is needed.In the current anti-reflection technology of coal seam,blasting anti-reflection has a wide range of application.On the basis of explosion mechanics,rock mechanics and fracture mechanics,this paper analyzes the research results of blasting antireflection by scholars at home and abroad,and summarizes the antireflective mechanism of deep hole blasting.According to the similarity theory,Taking C13 coal seam and its top and bottom floor of Pansan Coal Mine of Huainan Group as the simulation prototype,the similar proportion test is carried out,and the corresponding proportion is determined.The proportion material and proportion of coal seam are as follows: sand: cement: gypsum: mica powder: pulverized coal: water = 3.5 : 0.4 : 1.0 : 0.06 : 1.2 : 0.7.Then the experimental platform is built in the laboratory,the test model is poured,two kinds of charge rolls with different structures are made,and the similar simulation test of blasting antireflection is carried out.The hyperdynamic strain gauge and parallel electric instrument are used to collect the data in the test.by analyzing the test data of the hyperdynamic strain gauge,it can be concluded that after the explosion,the effect of the explosive on the surrounding medium is mainly concentrated in the dynamic load stage and the static load stage.At the 1 # position of the two test blocks,the strain peak value after directional shaped charge roll blasting is 1.22 times as much as that after ordinary charge roll blasting,and the static load stage after directional shaped charge blasting is 200 ns more than that of ordinary charge roll blasting.By analyzing the inversion diagram of the network parallel electrical instrument,it can be concluded that the electrical resistance jump range of the selected plane is about 38.9% when the test block is filled with the ordinary medicine roll.The jump range of the center position is about 66.7%.Compared with the isogram of resistance before and after the action of two different coils,the effect of directional shaped charge rolls on promoting fracture development in the direction of accumulation energy is better than that of common ones.The conclusions are confirmed from three aspects: the macroscopic surface crack of the test block,the dynamic strain in the blasting process and the electric inversion before and after blasting,which shows that the directional shaped charge roll can better promote the fracture development in the direction of energy accumulation.Increasing the permeability of coal seam and reducing the energy consumption in comminuted area can provide reference for engineering practice.Figure [47] Table [11] Ref.[86]... |
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