基于有限元计算的输电线路杆塔基础接地特性分析

Analysis on grounding characteristics of transmission tower foundation based on FEM

为了探究输电线路杆塔基础接地特性,应用有限元软件COMSOL对影响单基式杆塔基础接地特性的外敷接地体分段数和混凝土电阻率,以及影响多基式基础接地特性的外敷方式和浇注桩间距进行仿真计算,研究5种接地型式对接地电阻和地面电位分布的影响。仿真计算结果表明:对于单基式基础,外敷接地体分段数、混凝土电阻率对接地电阻影响不大,但外敷接地体分段数对分流系数有影响;对于多基式基础,整体外敷均压效果较好,浇注桩间距越大,接地电阻越小,地面电位分布越均匀;5种接地型式中,根开外围方框配合外敷柔性面状电极的经济性、降阻、均压的效果均为最优。该研究可为实际输电线路杆塔基础接地施工和结构优化提供一定的参考。

Lightning protection grounding project is the basis to ensure the safe and stable operation of transmission lines.Resistance reduction by natural grounding is an effective means of tower foundation grounding project.In this paper,the finite element software COMSOL is used,the effects of compartmentalization and the resistivity of concrete on grounding characteristics for single-pile foundation and the effects of wrapping mode and space among piles on grounding characteristics for multi-pile foundation are calculated.Effects of five grounding types on grounding resistance and ground potential distribution are studied.The simulation results show that for single-base foundation,the number of segments of external grounding body and concrete resistivity have little effect on grounding resistance,but the number of segments of external grounding body has influence on the diversion coefficient.For multi-base foundation,the effect of overall external pressure equalization is better,and the larger the spacing of cast-in-place piles,the smaller the grounding resistance and the more uniform the distribution of ground potential are.In the 5 grounding types,in terms of economy,resistance reduction and voltage equalization effects,the outer square box with flexible surface electrode plan is the best.This study can provide some reference for the actual tower foundation grounding construction and structural optimization.