Numerical Simulation And Application Of Radial Shaped Charge

Radial shaped charge is on the basis of traditional conical shaped charge, which is characterized ring structure, different from the cone shaped and linear shaped. When the radial shaped charge is detonated by detonator, under the action of detonation pressure radial shaped be overwhelmed, and forming the 360°and axis vertical circular jet outward or within injection, which achieving the goal of target damage multiple direction at the same time. It is because of the structural characteristics, makes the radial shaped charge has extensive applied value in military and industrial, and carry on the design and research is of great significance.Due to the low efficiency and the blasting vibration strength problem of cut blasting in rock drivage, as well as on open mine bench blasting such as subdrilling and uneven rock fragmentation. On the basis of the "first cutting then slotting" idea, by changing the charging structure to raise the utilization ratio of blast hole and rock breakage rate, reduce the blasting vibration, and eliminate or minimize the subdrilling. The length of cyclical footage had been improved.A radial jet cracker was proposed based on the shaped energy principle and the forms of blast hole, and the experiments have been carried out to verify its feasibility. For this cutter, the shell materials are used to be shaped materials and multiple shaped ring is designed on the circular tube. After explosion, multiple radial shaped jet can be formed along the axial line at the same time and then the surrounding medium would be penetrated. In order to reduce the impact of the result of the experiment by shell exploded fragment, the V-groove rings of shell tube inside are full of explosives, while the rest of shell tube are filled with charge divider device. By this method not only explosives are saved a lot and detonation energy can be reasonably distributed, but also can effectively avoid jet deflection caused by endpoint detonating. Studied on the penetration performance of small size radial jet cracker basis of the optimizing structure. Finally, the force condition of radial shaped jet in the movement process is analyzed. Due to the structure features of the radial shaped charge is easy in the radial tensile under the existence of the velocity gradient, and tangential shear under the dual role of the head to the slug turn into discontinuous point jet disc, so excessive height of burst will lead to jet penetration ability fell sharply.According to the similarity criterion, carried out the simulation experiment of cut blasting in the seamless steel pipe pouring cement mortar. The experimental results show that cut blasting effect can be improved a lot by the radial jet cracker, the utilization ratio of blasting hole achieved as 98%. The radial jet cracker explosion mechanism of crack was analyzed combined with jet breaking rock and rock blasting principle. As a result of the shaped jet penetration effect, to produce initial induced crack in the wall of hole, then the cracks were further propagated under the effect of subsequent explosive gases and joint action of stress concentration, and the cracks network were created. Finally, the following one conception is put forward according to radial jet cracker:solving the subdrilling and rate of large boulder in bench blasting.Numerical simulation as one of the effective technical means of studying shaped charge, can reappear the jet formation microscopic process, and make up for the deficiency of the experimental measurement technology, able to save experimental cost at the same time, provide theory reference for the research on the mechanism of the shaped charge jet.3-D numerical simulation of the formation process of radial shaped charge jet has been conducted using commercial LS-DYNA software. The different methods of detonating is studied through axially symmetric algorithm to the influence of the jet forming and jet velocity. Calculated results show that due to the effect of superposition of the detonation wave, the head velocity of jet produced by two-side symmetric initiation is the highest, and center point initiation takes the second place, and endpoint initiation is lowest. Detonation wave of the endpoint initiation in the form of asymmetric effect in shaped ring on both sides, and on both sides of the detonation pressure peak value is vary widely, so the formation of the jet off symmetry plane motion. The same cross section size of the cone, linear and radial shaped charge penetrating the target plate are numerically simulated, and compared the three typical shaped charge to the penetration ability. Fluid-structure coupling method is used for small size of the radial jet cracker penetrating steel target to carry on the numerical simulation. The simulation results are in good agreement with the experimental results. The small size of the radial jet cracker has enough penetration ability, so it can be produce strong penetration effect to brittle material such as rock to easy to form initial induced cracks, then create conditions for the crack and craze of the rock.Shale gas reservoir with low porosity and extreme low permeability of physical characteristics, which influences the shale gas mining efficiency greatly. A flexible radial jet cracker was proposed for shale shaped crack using radial jet cutting disc produced by blasting to rapidly penetrate the rock mass, and initial induced cracks was formed in the rock walls on the basis of the original work. Rock mass with the initial induced cracks further expanded under the effect of blast vibration and high energy gas, and together with the original natural fractures in shale formation with a wide range of interlaced network, which can increase the porosity and permeability of shale, and create favorable conditions for the next hydraulic fracturing. The function mechanism of the cracker was verified through the simulation of cutting steel tube, and numerical simulation of the process of penetrating concrete target by radial shaped charge. The simulation results show that radial shaped charge can produce a large number of radial damage cracks, and further extended to form mutual crisscross complex crack network.