Electrical Conductivities Of Ionic Contaminated Saturated Sandy Soils And TDR Measurement

With the development of industry, more soils were contaminated by heavy metal which will endanger our health. It is important to prevent contamination through monitoring the soils contaminated by heavy metal, which is also a hot subject for geoenvironmental engineering. The electrical conductivity of the soil solution directly shows the contamination concentration of the soil .Accordingly, through monitoring the electrical conductivity of the soil solution, we could obtain the degree of contamination of the soil.The dielectric constant, electrical conductivity of the soil and their test method by TDR were discussed. Based on the studies of the probe type, material and length of probes and the spacing and diameter of robs, a new type of probe was produced for the experimentation and the probe calibration method was established.The relationship between the electrical conductivity of the soil and the electrical conductivity of the soil solution of standard sand, coarse sand, medium sand, fine sand, mixed sand, silty sand and silty soil were researched. The influence of temperature, porosity and ion type for the electrical conductivity of the soil was studied. After comparing three different theoretical models, we find that Archie's law is the best one for saturated sandy soils. Based on the test result, the m exponent of Archie's law equals to 1.457 for saturated sandy soils.New method for testing the electrical conductivity of the soil solution of saturated sandy soils was presented based on TDR measurement and Archie's law. The new method was proved to be feasible and useful by model experiment. So it is possible to monitor in-situ ionic contamination of saturated sandy soils by the TDR measurement.