Research On The Formation Mechanism And Penetration Performance Of Linear Hypercumulation

Shaping control is the research forefront and major issue of rock blasting theory and technology,which has great scientific significance and application value.Directional fracture blasting with classical linear shaped charge(CLSC)shows the defects of small jet mass and low jet velocity,because of much more complex and difficult geological condition.Hyper shaped charge was proposed in recent years to dramatically enhance jet velocity and mass.The new structure changes the collapse model of liner by adding an additional liner,showing great potential to be combined with CLSC to generate the linear hypercumulation(LH)with much higher penetration performance.LH is able to improve shaping effect,reduce charge mass,and accelerate construction,and the structure is relatively simple with enough feasibility.At present,the research methods of domestic scholars on the structure of hyper shaped charge are usually simple,with fuzzy understanding of the formation process of LH.To develop the formation theory of LH and provide theoretical guidance and experimental data support for the application of hypercumulative blasting technology,it is necessary to conduct a more in-depth and comprehensive multi-angle analysis on the formation mechanism of LH and the factors affecting its penetration performance.In this paper,the formation mechanism and penetration performance of LH are studied through the combination of theoretical analysis,numerical simulation,and experiment.The main research content and conclusions are as follows.(1)The formation process of LH with ?-type liner is analyzed theoretically by simplifying the process as one projection and twice collapses,and finally establishing a calculation model of LH velocity based on the steady Birkhoff theory,in addition,the steady and quasi-steady theories of jet penetration are summarized to preliminarily analyze the factors affecting jet penetration performance.(2)The structure factors of linear hyper shaped charge(LHSC)are analyzed comprehensively.Then the influence of liners' materials on jet penetration performance are examined by numerical simulation.Combined with the design theory of CLSC and experiment data,the primary structural parameters are preliminarily designed,and the optimization scheme of the parameters are finally obtained by orthogonal test of numerical simulation.(3)Numerical simulations are carried out on LH and its affecting factors based on the optimized structure to improve penetration performance of the LH.Comparative study with conventional jet indicates that the variation characteristics of the pressure and velocity of the LH correspond well to the three stages of LH formation in the theoretical analysis.Control variable method is used to reveal the influence mechanism of the liners' primary structure parameters on the LH performance.It is beneficial to the penetration performance of the LH when decouple coefficient is set as 2 and the connection method of the primary liner and the additional liner is selected as adhesive.(4)Four groups of penetration experiments on rubber bar are conducted with classical jet and the LH of different apex angle of the primary liner,protruding length and width of the additional liner.The results show that the penetration depth of the LH based on the optimized structure is the maximum,nearly 100% higher than that of classical jet.The experimental results are almost consistent with the simulation analysis,verifying the effectiveness of the optimized structure,indicating that it's feasible and accurate to optimize the structure parameters of LHSC by orthogonal test of numerical simulation.