钢筋网和钢筋混凝土屏蔽效能研究

Study of Shielding Effectiveness of Reinforcing Bar Mesh and Reinforced-Concrete

利用矩量法和时域有限差分法计算分析了由钢筋网和钢筋混凝土构成的实际屏蔽体的屏蔽效能,总结了钢筋直径、钢筋网格尺寸和混凝土特性等因素对屏蔽效能影响的基本规律。通过对实际钢筋网屏蔽体屏蔽效能的测量进一步验证了所用数值计算方法对于计算此类问题的有效性。分析了无限大金属网屏蔽效能计算公式在计算钢筋网屏蔽体屏蔽效能的参考价值和局限性。探讨了使用钢筋混凝土作为变电站保护小间屏蔽材料的可行性,为实际工程设计提供了依据。

For EMC compliance, the study on the shielding effectiveness (SE) of the reinforced-concrete is valuable. Because the SE of reinforced-concrete is mainly depended on the reinforcing wire in it, and it is convenient to calculate a complex structure with metal wire structure by moment method (MoM). The SE of actual shielding built with wire-mesh reinforcement is studied by NEC software based on MoM. At the same time, the SE of a model built with wire-mesh reinforcement is tested and the results of experiment also prove that the numerical method used in the paper is validity. Furthermore, the reference value and limitation in the computation of the actual shielding by the analytical formulas, which are used in the calculation of SE of infinite metal mesh are analyzed. In order to analyses the SE of the actual shielding built with wire-mesh reinforcement and reinforced-concrete for transient electromagnetic field, the finite difference time domain method (FDTD) is also used. Finally, the factors that can affect the SE of the reinforced-concrete such as the size of the grid, radius of the reinforcing wire and others are summarized. In order to reduce the cost of engineering, the feasibility of using reinforced-concrete as shielding material for the relay-cell in substation is studied. Some valuable conclusions are reached.