| Due to the large pulse energy,wide spectrum and wide range of action produced by nuclear explosion,it can not only enter the electronic system through different coupling ways,interfere with the normal use and work of electronic equipment and communication system,but also damage some sensitive components such as electronic equipment and computer system to varying degrees,and even lead to the complete paralysis of the whole system.Therefore,it is of great practical value to study the coupling between EMP and pipelines,tunnels and cables.In this paper,the typical protection engineering is selected,and its simplified structure model is constructed.Considering the coupling effect of ventilation duct,tunnel and other ways,the coupling simulation of nuclear explosion electromagnetic pulse environment is carried out.The main contents of this paper are as follows:(1)The electromagnetic calculation model of typical engineering is established.In this paper,a multi-media geometric model of the mountain,tunnel,reinforced concrete and ventilation duct is established.The mesh model of triangular patch is obtained by the geometric model of discrete typical engineering.On this basis,the FDTD model is established by projection intersection method.(2)FDTD based on the periodic structure of OpenMP parallel platform is realized,and the transmission characteristics of reinforced mesh and reinforced concrete layer are calculated by this method.The results show that the thickness of concrete layer and the electrical conductivity have great influence on the amplitude of HEMP transmission wave.The resonant frequency of concrete is related to the relative dielectric constant and thickness of concrete layer,but not to the electrical conductivity.In reinforced concrete structures,the attenuation of HEMP mainly depends on the reinforcement mesh,and the mesh size has a great influence on the pulse.The resonance phenomenon will appear in the double-layer steel mesh,which leads to a significant decrease in the reflection coefficient of the pulse and greatly reduces the attenuation characteristics of HEMP.(3)Based on the half space FDTD method,the electromagnetic characteristics of HEMP propagating through different coupling paths in protection engineering are analyzed.The analysis shows that the field coupling energy of HEMP passing through a circular vent with a diameter of 1.5m is very small,and its influence on the internal electronic equipment can be ignored;When all the protective engineering doors(shock wave protection,moistureproof,shielding,etc.)or two doors are closed,the peak electric field intensity of HEMP entering the mountain through this coupling way is within 1vgm;When HEMP is obliquely incident,the electric field intensity of the pulse directly passing through the mountain and the reinforced concrete layer above the tunnel to the interior of the tunnel mainly depends on the structure of the reinforced concrete layer laid in the tunnel. |
PDF Full Text Request