Structural Effect Of Water Coupling Charge In Open-pit Deep Hole Bench Blasting

In recent years,the state has higher and higher requirements for mine environmental protection,and requires to practice the development concept of "green water and green mountain is golden mountain and silver mountain" in mine development.Green mine construction is an important work in mine development in recent years and for a period of time in the future.How to reduce the amount of charge,reduce blasting dust,improve blasting effect and implement the concept of green blasting in green mine construction is the subject concerned by the majority of blasting workers.In the open-air bench deep hole blasting,the blasting effect of interval charging is better than that of continuous charging,but it has the disadvantages of large amount of booster equipment and high cost.The water medium axial coupling charge blasting technology is of great significance to reduce explosive consumption,control blasting dust,improve blasting effect and practice the concept of green blasting.In this paper,three different charge structures of axial coupling of water medium are compared and analyzed,and the charge structure corresponding to the optimal blasting effect is found.Based on the optimal water medium axial coupling charge structure,the optimal water medium length is found by comparing the explosion stress field with different water medium length.The research has achieved the following main results:1.This paper summarizes the attenuation law of explosion shock wave formed by blast hole charging blasting in rock mass,from near to far explosion shock wave,stress wave and elastic vibration wave,and analyzes the relationship between three different characteristic waves and crushing area,fracture area and elastic vibration area.The calculation of the initial impact pressure of the hole wall of the water medium axial coupling charge structure is analyzed,and the effective stress rock breaking theory of the water medium axial coupling charge structure is analyzed.Based on the Mises yield criterion,the peak value of the effective stress is compared with the dynamic tensile strength of the rock to judge whether the rock is damaged or not.The calculation methods of crushing zone and fracture zone under the condition of water medium axial coupling charge are summarized.2.Using ANSYS/LS-DYNA finite element software,(1)plugging-water-medium-explosive;(2)Plugging-Explosive-water medium;(3)Plugging-water medium-Explosive-water medium;The models of three different water coupled charge structures are established,and the numerical simulation calculation is carried out.The effective stress,vibration velocity time history curve and the relationship curve between the peak intensity of effective stress and different distance from the blast hole are compared and analyzed.It is found that the water medium charge structure at both ends is better than the other two charge structures.3.In the case of plugging water medium explosive water medium charging structure,five groups of models with different water medium lengths are numerically simulated.It is concluded that under the condition of the research model,when the water medium length of1.7m(0.85 m in the upper part and 0.85 m in the lower part)can be added to the water medium axial coupling charging structure,a good blasting effect can be obtained.4.The bench blasting test of the water medium axial coupling charging structure and the anhydrous medium continuous charging structure is carried out.It is found that the water medium axial coupling charging structure can effectively solve the problems of large amount of blasting dust,high lump rate and root phenomenon,improve the utilization rate of explosion energy and reduce the use of explosives.Under the condition of field application,when the length of water medium added at both ends of the explosive is 0.85 m,the blasting effect and related indexes can be better,which is basically consistent with the results of numerical simulation.