Correlation of Electrical Resistivity with Unconfined Compressive Strength, cu for Clay Particles

Precise determination of the engineering properties of the soil such as soil strength is required for a proper design and successful construction of any structures. Conventional method that uses borehole sampling is generally time-consuming and very expensive. Thus, it is desirable to use geophysical method that is more rapid and non-invasive as an alternative. The use of electrical resistivity by geotechnical engineers has been increasing all over the world. It is a convenient method to evaluate spatial and temporal variation of moisture and heterogeneity of subsoil. This research presents the relationship of electrical resistivity with unconfined compressive strength, porosity and saturation of clay size particles. Soil samples were mixed with distilled water and left for 24hours. Electrical resistivity tests using basic multimeter, steels moulds and other related equipment were conducted in the laboratory on KM80 clay soil samples with the variations of numbers of blows and moisture content. The electrical resistivity as well as unconfined compression test had been done right after the compaction test. The value of electrical parameters such as voltage, current and resistance with corresponding value of soil parameters such as unconfined compressive strength, porosity and saturation were all recorded. The results of the tests produced some initial crude relationship between electrical resistivity and the selected parameters. Generally, the relationship between resistivity and unconfined compressive strength is proportional. On the other hand, some unique trends of behavior were observed for relationship between resistivity with porosity and saturation. Overall results showed, as the resistivity in clay increases, the unconfined compressive strength of the soil sample also increases. In order to achieve more precise correlations, more additional investigation and experiments need to be conducted.