电极布置对电阻率精确性影响的试验研究与仿真分析

电阻率法在土壤测试的精确性方面存在较多不足，而电极是影响精度的重要原因，尤其是二极法测试。若能确定电极与土壤的接触程度，以及两电极间距离对测试结果的影响，将可最大化避免电极的干扰。基于二极法电阻率测试方法，选用锌污染标准砂作为模拟土壤，以测试交流电阻率为例，设置不同接触程度与不同电极间距两种工况，并结合COMSOL软件仿真分析，研究电极布置对电阻率测试的影响，并建立分析模型与误差计算式。研究结果表明：试验与模拟分析可相互验证和补充。接触程度越大，越有利于电阻率测试，随接触程度增大对测试电阻率的影响逐渐减弱；电极间距越大，对测试电阻率的影响越弱，细长型试样更有益于提高测试精度。导电模型分为正常段与受电极影响的过渡段串联，同时，径向电流密度可较好表征出各段的长度和极化情况。过渡段长度和极化随接触程度的增大而减小，与电极间距无关，通过电极布置模型可拟合不同电极间距的测试结果，得出正常电阻率。

Experimental and simulation analysis on influences of electrode arrangement on resistivity accuracy

There were many deficiencies in the accuracy of soil resistivity test technology, and electrode arrangement is an important reason, especially in two-electrode method. If the contact between electrode and soil and the distance of two electrodes can be controlled, electrode influences will be avoided to the greatest extent. Therefore, based on two-electrode test model, zinc-contaminated sand was selected as simulated soil to test its AC resistivity. Electrode arrangement conditions of contact degree and electrode distance were set up, and the influences of them on resistivity measurement were studied combining with COMSOL simulation. The influences of electrode arrangement on resistivity test were studied, and an analytical model and error calculation formulas were established. The results show that test and simulation can verify and supplement each other. The greater contact degree, the more favorable resistivity test, and the influence of contact on resistivity test gradually decreases as it increases. The greater electrode distance, the weaker effect on resistivity test and the slender sample is more beneficial for improving the test accuracy. Conductive model is divided into two transition segments and normal segments in series based on whether it is affected by polarization. The length and polarization of each segment are characterized by radial current density, which decreases with the increase of contact, but slightly affected by electrode distance. Normal resistivity can be obtained by fitting the testing results under different electrode distances using the electrode arrangement model.