Research Of Method Based On The Resistivity Test Of Determining The Sandy Soil Porosity And Its Application

Soil resistivity is the basic parameters of characterizing the soil electrical conductivity. It is one of the inherent property of soil parameters and mainly determined by the composition and structure characteristics of the soil. The characteristics of soil resistivity index that can analyze soil granule composition 、structure characteristics and determine the engineering mechanics properties of the soil can be determined by indoor test. Practical structural model is established by quantitative analysis of soil structure. Engineering mechanics parameters can be effectively measured that have great significance in theory and engineering application prospects.Method of measuring soil porosity by electrical resistivity is developing vigorously in recent years, it has been applied in engineering geology, hydrogeology, environmental monitoring and other fields. The difficulties of test trouble and quantitative analysis in the traditional soil structural research can be overcomed by the method of soil resistivity test.First of all in this paper, the different forms of test probe can be used in comparison test trials, selecting and determining electrical resistivity test probe for the specific soil box. It is based on the theory of two-electrode method,a series of comparative tests are completed by changing the electrode type(copper sheet, brass wire mesh, fine copper bar) and controlling electrode spacing, penetration depth etc, and the appropriate test method and correction method has been determined. And then influencing factors of unsaturated soil and saturated soil resistivity were studied through the test. The general rule of relationship between resistivity and saturation and the value of standard sand saturation were determined by fitting the experimental data. The relationship between saturated standard sand and the resistivity and porosity were studied based on Archie’s formula. At last, the ion exchange coefficient and the cementation exponent were obtained. And finally, the model of the relationship between relative compactedness and structure factor of saturated standard sand were established. The result will significantly promote the evaluation of sand liquefaction.