电缆隧道中盾构接地系统接地电阻计算及测量

Calculation and measurement of grounding resistance of grounding system using tunnel foundation in cable tunnel

接地电阻是接地系统安全运行的重要参数之一。本文提出了考虑钢筋水泥层电阻率时,盾构接地系统(基于盾构结构的接地系统)接地电阻的计算方法。基于半球形接地极,给出计算双层土壤介质时等效电阻率的方法,并将该方法推广到盾构接地系统,计算钢筋水泥层和土壤双层介质的等效电阻率,从而采用已经被提出的简化计算公式求解盾构接地系统的接地电阻。同时采用三极法测量北京市岳各庄220k V电缆隧道盾构接地系统的接地电阻。测量结果表明,本文方法计算值偏小,与测量值相对误差在10%~32%之间,可用于计算盾构接地系统接地电阻。

The grounding resistance is one of the important parameters for the safe operation of the grounding system. The method for calculating the grounding resistance of grounding system using the tunnel foundation（ GSTF）and considering the cement layer resistivity is provided in this paper. Based on the hemispherical electrode,the method for calculating the equivalent soil resistivity of the two-layer soil is described. And it is used to solve the equivalent resistivity of cement layer and soil in GSTF. Then,the simplified formula has been provided which can be used to calculate grounding resistance of GSTF. At the same time,the three-electrode method is chosen to measure the grounding resistance of GSTF in Yue Ge village. The results show that the value of calculation using the method provided in the paper is less than that of the measurement. The relative error between these results is from 10% to32%. And the method described in the paper can be used to calculate the grounding resistance of GSTF.