Numerical Simulation Of Blasting Cracking For Semi Infinite Rock Mass With Cylindrical Charge

In order to ensure blasting-expansion achievement in the ultra-deep borehole,weaken the loss of cutting tooth,the wear of small chute and large chain,reduce the vibration of whole instrument and lower the dust level,when the cutting ability is weaker than rock strength,the blasting scheme was optimized and numerical simulation of blasting expansion in the semi infinite rock mass was carried out,the relationship of the radius of explosive filling and the expansion radius of the blasting were obtained.The results has been applied in a pilot blasting,the parameters of which were determined.The theoretical calculation model and the parameters selected in this study are proved to be reasonable,which can provide the basis for the design for the blasting project under similar conditions.The research work was carried out in the following five aspects.First,the research results of the numerical simulation of rock blasting at domestic and abroad are investigated.It is found that the ratio of charge radius to the radius of the fracture zone is large,which is not suitable for field blasting design,therefore it is necessary to further study it according to the actual field practice.Second,the characteristics and occurrence conditions of the rock mass in the field were carefully investigated and studied,and the details are determined.The fine sandstone was proved to be the representative rock which restricts the driving of the roadheaders.Static and dynamic parameters of the rock are measured,and the fracture characteristics of the fine sandstone under impact load were studied,based on which the numerical simulation model and parameter values were selected.Third,according to the experimental research results,the theoretical calculation model and the dynamic tensile strength of the numerical simulation are determined.Fourth,by using the numerical simulation software,the models of crack expansion characteristics and relationship between the radius of charge and the radius of the expansion zone were set up respectively.At a real project,the quantitative relation between the two radius was obtained.Fifth,the blasting scheme was designed based on the numerical simulation results,and the experimental blasting effect has reached the expected goal.The reliability of the numerical simulation results was verified,and the consumption of the cutting tooth was reduced by 59%,the dust concentration was reduced by 49.9%,and the cost of the tunneling cost was reduced about 3500 yuan per meter.The research results can provide useful references for similar projects.