Research On Blasting Technology Of Converging Detonation Wave Collision

It is an important issue in engineering blasting to improve the utilization ratio of explosive energy.Although the shaped charge and controlled blasting technology can realize the purpose of increasing the local detonation pressure,it is difficult to be widely used in engineering blasting due to their complicated process and limited application conditions.In this study,a novel method was proposed to realize the detonation wave collision in the borehole.This method has the advantages of more convenient operation,higher utilization ratio of borehole and less influenced by the internal water,and can be popularized into the engineering blasting with high clamping force like hard rock excavation,roadway excavation and rock-plug blasting.In this paper,it is combined that the experiment method,theoretical analysis,numerical calculation and industrial application,and a complete set of research techniques of detonation wave collision was established.The main contents include the following aspects:(1)A novel method of the converging detonation wave collision was proposed.In this method,two or more high explosive strips are arranged uniformly to initiating the main charge in the borehole.The detonation wave collision is formed in the borehole,and then the cumulative effect is generated.This novel method does not need to use the shaped cover and concavity,which is not only avoids the material waste,but also the operation is simple and may be used in the water hole blasting,and the loading amount of explosive in the hole is also improved,in a word,it is more suitable for the blasting engineering with large clamping force.(2)A series of basic blasting experiments were conducted to study the cumulative effect of detonation wave collision from qualitative to quantitative,and a set of experimental method of converging detonation wave collision were established.First of all,the non-uniform etching phenomenon of the detonation wave collision effect on the central axis was observed by means of the etching and reaming experiments.Then,the explosive brisance test results show that the primary explosive and the main charge meet a certain proportional relationship of detonation velocities when using the converging detonation wave collision.It is concluded that the depth of the borehole increases by 80%compared to that of the detonator initiating based on the power test of explosive.Finally,a crack extraction test groove was designed to simulate the rock burst state.The experimental results show that the converging detonation wave collision can change the energy distribution of the explosion.(3)From the view of theoretical analysis and numerical calculation,the converging detonation wave collision mechanism was analyzed.Firstly,based on the Mohaupt effect theory of the detonation wave collision,the detonation pressure change process of frontal collision,oblique reflection and Mach reflection of detonation wave were analyzed.It is observed that the Mach reflection generates when the incident angle is 46.8°for the industrial explosive with 0.9g/cm3 density.The pressure ratio of detonation wave collision varied from 2.41,2.3-2.48 and 3.08 times.And in order to realize the detonation pressure increase 2 times,the detonation velocity ratio at least 1.15 times of the high explosive strips to the main charge.Then,the flow field of planar and axisymmetric two dimensional high speed linear primary explosives was solved by using the conical flow theory.The numerical calculation was used to describe the process of detonation wave propagation and the effect of detonation wave collision.The result of single-hole show that the detonation pressure of Mach reflection is 3.15 times more than stable detonation,and then forms a larger crack.Double-hole results indicate that the maximum impact pressure can increase by 84.21%,and the internal energy increase by 3 times than center initiating.The simulation results by Material Point Method(MPM)show that the linear particle flow dissipation was the main reason of the lower compression value of brisance test.(4)The process method of the converging detonation wave collision in different blasting environment was designed for the industrial applications of pile,underground shield boulder and open-pit mining blasting.Pile blasting results show that the symmetric bilinear initiating technique can decrease the unit explosive consumption by 60.48%,and increase the blasting footage by 128.57%.In the shield underground boulder blasting,the shield tunneling rate is increased by 42.74%,and the blasting cost is reduced by 26.74%.Open-pit mining bench blasting results show that the converging detonation wave collision technique can improve the homogeneity of rock fragmentation and avoid the tight bottom.Based on the techniques in this paper,the converging detonation wave collision can yield satisfied outcomes in engineering blasting.