| In this study,the boulder and prominent rock appearing in the process of subway construction are taken as the research object.The large-scale numerical simulation software is used to simulate the perforation bomb to invade the rock medium and simulate the damage effect of the rock medium under the shaped charge jet.In the research process,the orthogonal contrast test is used to explore the optimal design and configuration of the perforating projectile,which is of guiding significance for the construction of the stone and the lone stone in the construction process of the subway tunnel.The main research work and achievements are as follows:1.The theoretical model and material parameters of explosives,metal coatings,micro-weathered and moderately weathered granites used in numerical calculations are determined,which lays a good foundation for accurately describing the characteristics of rock damage.The finite element calculation model of the interaction between perforating projectile and rock is established.The three-stage typical characteristic(The hood is compressed and deformed,the metal jet is stable,and the metal jet is broken.)analysis of the perforated projectile shaped jet is obtained,and the regularity of rock damage at different stages in the jet forming process is obtained.2.Based on the orthogonal optimization design,the basic structural parameters of the perforating projectile with the maximum penetration depth of the rock are: the apex angle of the coating is 90°,the charging diameter is 58mm(the charging quality is 225.76g),and the wall thickness of the coating is 1mm.The height of the perforation is set to 10cm;the structural parameters of the perforation of the most cracks on the rock are: the apex angle of the coating is 90°,the charging diameter is 58mm(the charging mass is 225.76g),and the wall thickness of the coating is 2mm.Set to 2cm.3.The effect of explosives on the damage of rock medium targets is proved.The numerical simulation results show that when the bombing height is less than 3cm,the shaped charge jet generated after the perforating bomb explodes with the explosion field to generate a large number of cracks to meet the basic engineering requirements.When the bombing height exceeds 3 cm,the maximum penetration depth of the jet continues to increase.However,the damage caused by the explosion field generated by the explosive explosion at this time is greatly reduced,resulting in a sharp decrease in the number of cracks.Considering the actual engineering requirements,we recommend that the height setting should not exceed 3cm.At the same time,the influence of the weathering degree of rock media on the penetration effect is also verified.The higher the degree of weathering,the deeper the penetration depth.4.Multi-perforation bombs are used to damage the rock,and the shock wave intensity of the rock is characterized by sudden rise,fluctuation,and duration.The detonation field generated after the detonation of the perforating charge and the coupling effect of the jets forming the jet on the rock penetration increase the damage of the rock after the multi-perforation bomb is detonated.5.Equipped with a perforating gun capable of obtaining more cracked perforating bullets,the distance between the two elastic frames should not exceed 80 cm during the construction of the site.On the contrary,it is difficult to generate a penetrating crack inside the rock after the perforating bomb is detonated,that is,a complete failure mode is generated for the rock.Equipped with a perforating gun capable of obtaining a deeper deep hole bomb,the distance between the two elastic frames should not exceed 60 cm during the construction of the site.When the distance between the two frames is less than 60 cm,the rock between the two frames can be destroyed. |
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