Controlled Blasting Mechanism Of Directional Fracture Of Rock With Split-tube Charge Holder

The directional fracture controlled blasting technology of split-tube charge holder has been widely used in deep geotechnical engineering,underground chamber engineering,precious stone mining,tunnel engineering,highway and railway cutting excavation engineering,mining and other fields related to engineering blasting.It promotes the promotion and application of precision blasting concept in China.The split-tube charge holder technology is of great advantage to simple process,convenient construction and excellent effect.In order to make better use of split-tube charge holder technology,and clarify its mechanism,in this paper,various directional fracture controlled blasting technologies were reviewed in detail,and the numerical simulation technology of explosive shock phenomena was introduced,too.Through theoretical analysis,experimental research and numerical simulation,this paper systematically studied the blasting mechanism of split-tube charge holder,and its directional controlled blasting mechanism.Finally,the application and optimization of split-tube charge holder in engineering blasting were also studied.A major description can be drawn as follows.(1)The fundamental reason for the significant effect of the directional control blasting of the split-tube charge holder is the effective distribution of the explosive energy by the split-tube.Its essence is to cut or punch a hole in a circular tube with a certain density and strength.And through the shape,quantity or angle of the slit(hole)to control the distribution of the explosion stress field and the quasi-static effect and sharp-point effect of the explosive gas on the medium,and finally achieve the purpose of directional control blasting.In this paper,based on the high-speed schlieren test results of the double-slot/coupling split-tube charge holder detonation behavior,the ‘explosive-pipe-air' model was established,and the mechanism of directional control blasting was studied by theoretical analysis and numerical simulation.The shock wave interaction during the explosion process,the dynamic behavior of the explosive gas and the temporal and spatial distribution of pressure were analyzed.(2)Taking the rock blasting of the split-tube charge holder as the research object,the mechanism of explosive rock blasting and the internal and external effects of the explosion were introduced in detail.Based on the lead cylinder blasting test results,the elastoplastic theory and rock fracture mechanics theory werw used to systematically analyze its mechanism.Finally,the numerical simulation method was used to study the directional blasting mechanism of the split-tube charge holder.The blasting effect of single hole traditional and split-tube charge holder blasting,the change of characteristic elements pressure and stress time history during blasting were compared and analyzed.(3)Taking multiple charge blasting as the research object,the blasting mechanism of multi-charge in medium was introduced.Based on the model parameters in the references,the traditional and split-tube charge holder of multiple charge were compared and analyzed by numerical simulation method.Finally,the application of split-tube charge holder blasting in smooth blasting of rock roadway was studied by numerical simulation method,and the blasting scheme was further optimized.This thesis includes 77 figures,12 tables,and 136 referances.