Study On Rational Toe Burden And Initiation Position Of Shangli Mine

Nowadays,because of the surge of production demand,the bench blasting operation scale of open-pit mine is correspondingly expanded,resulting in the root and block problems frequently appear in front of people.In order to ensure the normal production and operation of the mine,it is urgent to solve the root and block problems.The reason is that the frequent occurrence of the root and the big block is closely related to the blasting parameters such as the toe burden and the initiation position.In order to obtain a good blasting effect,reduce the base rate and bulk rate,and improve the production efficiency,therefore,the research on the rationality of blasting parameters in bench blasting has become the research focus of blasting related industry and scientific researchers.Based on the analysis of the rock breaking mechanism of open-air steps,the factors affecting the blasting effect and the actual working conditions,the subjective reason for the unsatisfactory blasting effect at present in Shuangli iron mine is mainly that the relevant technical parameters refer to the past experience and lack of scientific theoretical basis;the objective reason is the large clamping effect of the bottom and the existence of joint fissures.The above-mentioned causes directly lead to the frequent occurrence of root and block phenomena,so it is proposed to improve the blasting effect by setting a reasonable toe burden and the position of the initiation point,providing scientific theoretical basis for the blasting parameters and other relevant measures.According to the actual engineering of Shuangli iron mine,based on the theoretical calculation and the modified chassis resistance line,the initiation position and other relevant blasting parameters,this paper establishes 16 sets of bench blasting models about the toe burden of 5.0m,5.5m,6.0m,6.5m and the initiation point of 0.5m,1.0m,1.5m,2.0m by Creo CAE design software,Altair HyperMesh module in HyperWorks and LSDYNA solver.By comparing the peak value of effective stress of each monitoring unit selected according to a certain interval distance from the blasthole to the bottom line of step slope in the process of blasting,whether the peak value of effective stress reaches the yield strength of rock is taken as the judgment basis of rock breaking,and the mean value of effective stress of each group and the duration of reaching the yield strength of rock are obtained with the help of the effective stress time history chart,so as to get the conclusion in the numerical simulation The result shows that the combination of 6.0m of chassis resistance line and 2.0m of initiation position has the best blasting effect.Based on the field test of 1876 horizontal north side bench blasting in Shuangli iron mine,the blasting test results of different chassis resistance lines and initiation points are analyzed.The test results are basically consistent with the numerical simulation results.It is proved that the combination of numerical simulation and practical engineering is a low-cost and high-efficiency way to solve the actual problems of the mine,which will provide suggestions for the future blasting work in Shuangli mine Some technical basis and reference are provided.