Abstract: By using alternating current(AC) bridge， the effects of the water content and electric current frequency on the electrical resistivity of soils were studied to investigate the relationship between resistivity and soil chemical weathering index (CWI). The test results show that the electrical resistivity of soils decreases with the increase of water content and electric current frequency. When the water content is relatively low， the electrical resistivity decreases very sharply with the increase of water content， but turned slowly at relatively high water content. However， the electrical resistivity has only a smaller reduction with the increase of the electric frequency. Based on the viewpoint of that the weathering degree is positively related to the electric resistivity， the relationship between resistivity and chemical weathering index was established， and the computing method for fitted parameters was given. A comparison between CWI predicted by fitted equation and actual CWI was made to show its reliability. The electrical resistivity can provide reference for the evaluation of the degree of weathering.

Key words: soil mechanics, electrical resistivity, chemical weathering index(CWI), water content, electric current frequency