大港土电阻率的测量及其导电模型

Electrical resistivity measurement and conductive model of Dagang soil

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.

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 solid-liquid phase can be ignored.