Research On Blasting Parameters Of Tunnel Excavation Under The Condition Of Coupled Charge Based On Numerical Simulation

According to the requirements of national reform and development of civil explosion industry and the development plan of civil explosion industry,in the future,field mixed explosives and related technologies and equipment will inevitably become the leading products for blasting in major mines.Charging mode of charge trolley is mainly coupled charge.After blasting,the detonation wave directly acts on the hole wall.Its working mechanism is different from uncoupled charge structure.But the blasting theory research of uncoupled charge structure is not applicable to coupled charge structure,so the blasting principle of coupled charge needs to be separately analyzed.Only in this way can it be suitable for the requirements of tunnel excavation blasting engineering design.Based on the subject background of Key Technologies of Residual Control in Roadway Driving Blasting,this paper studies the feasibility of mixed loading vehicle for blasting explosives in tunnel driving of Dahongshan Copper Mine.Through numerical simulation,the blasting effect of coupled charge under different structure of blasting hole arrangement parameters is studied,and whether there are holes or not is studied.The influence of diameter and arrangement of holes on the blasting effect of first blasting hole in cut blasting;By combining theoretical calculation with numerical simulation,the optimum parameters of coupling charge hole distribution are determined and verified by field test.Coupled charge structure has the characteristics of high peak stress,fast attenuation speed and short working time,which makes the near area of borehole more broken and a lot of energy is absorbed in the near area of borehole,accelerating attenuation of stress wave and reducing disturbance to surrounding rock.Comparing with the two methods of void or not,the void-free scheme mainly relies on the superposition of stress waves of two holes to break up and form penetration of surrounding rocks,while the void scheme relies on the reflection of stress waves at the void to generate tension stress waves,which form the tensile failure area between the holes and the compression crushing area around the holes to form penetration between the holes.The reflection of stress wave of holes increases with the increase of diameter,i.e.the larger the diameter of holes in a certain range,the better the cavity formed after the cut blasting.Compared with singlehole scheme,double-hole scheme can provide more free surface and compensation space,and there is a reasonable value of spacing between holes.The larger the distance between two holes within the reasonable value,the larger the cavity area will be,and the blasting effect will be poor when the spacing between holes is larger than this reasonable value.By means of numerical simulation,the hole layout schemes of single large diameter hollow vertical cut and double large diameter hollow vertical cut are determined.Both schemes can form a complete rock crushing area.Finally,by analyzing the field blasting effect,the section area of single large diameter hollow vertical cut is 5.04% larger than that of double large diameter hollow vertical cut.It can be considered that there is little difference between the two cut methods,but the two large diameter hollow vertical cut method has one more hole than single large diameter hollow vertical cut method.Considering the cost savings of hole punching,single large diameter hollow vertical cut scheme is better in tunnel cut blasting.Finally,single large diameter hole vertical cutting scheme is determined.The first hole is 30 cm away from the hole,the second section is 40 cm away from the hole,the third section is 45 cm away from the hole horizontally,the filling length is 45 cm,the linear charge density is 0.8,and the delay time between the holes is 50 ms.