Numerical Simulation Study On Block Contol Of Open-pit Large Diameter Deep Hole Blasting

With the continuous development of China's economic construction,blasting technology has been applied in various fields of national production.Among them,open-air blasting is widely used in coal mines and rock mines because of its relatively safe blasting environment and large-scale blasting mining output.As well as various field level constructions.In general,open-air blasting increases the mining efficiency by increasing the blasthole diameter,that is,the blasting method using large-diameter holes.As the diameter of the blasthole is increased,the configured network parameters must be increased accordingly,which causes the problem of large blasting block size and high block rate of the rock after blasting.Therefore,how to reduce the blasting degree of rock is a problem that needs to be solved urgently in open blasting.The degree of rock blasting is the result of an explosion where certain explosives are placed in the rock.The amount of explosives is different,the installation status is different,and the corresponding blasting block degree is different.To obtain a blasting block degree that meets the needs of the project,mainly depends on the reasonable blasting parameters and charge structure.After the blasting parameters of open-air deep-hole blasting are determined,it is generally believed that reconfiguration of air gap charges is an effective method to improve the blasting effect and reduce the blasting block size.When the air space is used for charging,the air space layer is mostly arranged in the middle of the blast hole.At this time,what is the ratio of the air gap to the blast hole space? The blasthole charge is divided into upper and lower parts,what proportion should the upper and lower charges be distributed? There is no clear and reasoned quantitative answer to these,and this is actually an important factor for whether the air space charge can improve the blasting effect and reduce the blasting block size.In this paper,through theoretical analysis of the axial axial uncoupled interval charge conditions,the influence of the change of the air interval ratio and the change of the upper and lower charge ratios on the rock breaking radius,it is found that there is an optimal interval ratio and charge ratio The breaking radius reaches the maximum.Through numerical simulation method,the central axial uncoupling air interval blasting model is established,and it is concluded that when the upper and lower charge ratio is 3:7 and the air interval ratio is 15%,there is no excessive stress concentration and stress distribution in the hole wall pressure Uniform,the highest effective average pressure in the hole,and the high pressure action time is long,which is conducive to the uniform distribution of rock fragmentation.At the same time,the calculation model when the blasthole density coefficient is 1.4,1.6,1.75 is constructed,and the above conclusions are verified.