Research and application of large aperture pre-splitting blasting parameters in open-pit mines
Presplitting blasting is an important means to control slope forming and reduce the effect of blasting dynamic load.In order to study the optimal uncoupling coefficient and hole spacing of pre-splitting blasting with hole diameter of 203 mm,a numerical model with uncoupling coefficient and hole spacing as variables is established by LS-DYNA.The crack growth and peak stress intensity around the hole under different working conditions are analyzed.The results show that when the air uncoupling coefficient is 2.53,2.90,3.38,4.06,5.07 and 6.77 respectively,the uncoupling coefficient is 4.06,the utilization rate of explosion energy is the highest and the crack propagation is good,which is consistent with the theoretical formula.Then,five groups of models with air uncoupling coefficient of 4.06 and hole spacing of 1.5,2.0,2.5,3.0 and 3.5 m are established.When the hole spacing is 2.5 m,the crack penetration condition between holes is satisfied,which meets the requirements of field working conditions.Moreover,the field application effect is good,which provides reference for similar projects.
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