适于降阻的输电杆塔预制式钢筒桩基础的优化方法

Optimization Method of Prefabricated Steel Tubular Pile Foundation for Transmission Tower Suitable for Resistance Reduction

输电杆塔接地装置的接地电阻直接关系着电力系统输电线路的防雷保护效果。钢筒桩基础在输电线路杆塔中的作用是保证杆塔结构的稳定性,并未充分利用其降阻效果,提出了一种不同土壤电阻下,适于降阻的钢筒桩优化长度的计算方法。利用CDEGS接地计算软件对钢筒桩基础的降阻效果计算,得到了不同土壤电阻率下钢筒桩基础的长度与杆塔工频接地电阻的关系变化曲线;以单位长度降阻率的阈值为指标,选取了钢筒桩的最优长度。针对高土壤电阻率地区钢筒桩基础自然接地的工频接地电阻仍不满足规程规定的问题,采用水平接地体和钢筒桩基础共同构成输电杆塔的立体式接地装置的设计方案,并给出了设计实例,以满足规程要求,为实际输电杆塔接地装置的接地设计提供了方法指导。

The grounding resistance of transmission tower grounding device is directly related to the lightning protection effect of transmission line in power system.The function of steel tube pile foundation in the design of transmission line tower is to ensure the stability of tower structure,while its resistance reduction effect is not fully utilized.The author puts forward a calculation method of optimal length of steel tube pile suitable for resistance reduction under different soil resistance.The resistance reduction effect of steel cylinder pile foundation is calculated by CDEGS grounding calculation software,and the relationship between the length of steel cylinder pile foundation and power frequency grounding resistance of tower under different soil resistivity is obtained.Taking the threshold value of resistance reduction rate per unit length as the index,the optimal length of steel cylinder pile is selected.In view of the problem that the power frequency grounding resistance of natural grounding of steel cylinder pile foundation in high soil resistivity area still does not meet the regulations,the design scheme of three-dimensional grounding device of transmission tower is composed of horizontal grounding body and steel cylinder pile foundation,and a design example is given to meet the requirements of the regulations,which provides method guidance for the grounding design of actual transmission tower grounding device.