Experimental Research On Blasting Crack Propagation And Controlled Under Eccentric Decouple Charge Structure

In the construction of smooth blasting, it is often difficult to locate the cartridge in the center of the holes, thus the cartridge will be eccentric, even the cartridge will form a local contact to the borehole wall,.The result is that blasting will cause a rupture of hole well rock within a certain range. Especially, for rock mass in which the joint fissure is growing, blasting can lead to the crushing of surrounding rock which would cause overbreak, additionally, it will affect the stability of surrounding rock. Therefore, to correct understand the influence of the charge structure for smooth blasting effect and surrounding rock steady state, study the crack law of rock mass and crack propagation control in the radial eccentric decouple charge blasting, and it has important theoretical value and practical significance in engineering.With the organic glass as the test medium, the detonator as explosive source, the eccentric coupling coefficient and the pitch as variables, the adding plastic pipes near the cartridge which is used to control the direction of action of blasting energy, this paper carried out many simulation experiments and theoretical analysis about the crack extension and control of the eccentric decouple charge blasting, then obtained a series of useful conclusions.First, with organic glass of which the thickness is 5 mm and 40 mm as the test medium, researched the crack distribution and propagation law under eccentric decouple charge blasting and different eccentric coupling coefficient, the result showed that the smaller thickness of the organic glass is more suitable as a medium of the blasting test; and meanwhile when the decouple coefficient is 1.71,it will get the best blasting effect.Then, with the different pitch which is 36 mm, 48 mm and 60 mm, the test has been done, the result showed that when the pitch range is36mm~48mm, the void has a guiding role for the formation of cracks between the holes.Finally, in order to control extension direction of crack and reduce the damage of surrounding rock, carried out 5 groups blasting tests with different eccentric coupling coefficient and wall casing located indifferent position. The test showed that, when the eccentric coupling coefficient is from 1.57 to 2, the wall casing can effectively control the direction of crack propagation.