大港土电阻率的测量及其导电模型

利用直流四电极法测量了不同含水量条件下的大港土电阻率,其电阻率随含水量增加而降低. 在测量中发现当外加电位梯度比较小时,所计算的电阻率ρ值相对较大;随着外加电位梯度增加,其电阻率逐渐减小,并最终趋于一个稳定的数值,特别是在含水量比较低的情况下,这种变化更为明显. 提出了一个土壤导电模型,利用等效电路的方法对土壤的导电性进行了讨论:在含水量较低时,主要是孔隙水液相和固/液界面上的交换性离子导电;在高含水量条件下,土壤主要是通过孔隙水液相导电,固/液界面上的交换性离子导电可以忽略不计.

Electrical resistivity measurement and conductive model of Dagang soil

The electrical resistivity of Dagang soil at different water content levels was measured by the means of DC four-electrode technology.The resistivity is lower at a higher water content level.During the measurement,the calculated value of resistivity is bigger at lower voltage grads;when the voltage grads increasing,it reduces and tends to a steady value,especially for low water content soil.A conductive model was presented,and soil conductivity was discussed by an equivalent circuit.At a lower water content level,the pathway of current flow is liquid phase pathway of pore water and solid-liquid phase pathway primarily via exchangeable ions.At higher water content the current passes mostly through pore water and the effect of exchangeable ions at the interface of solidliquid phase can be ignored.