Determination of Rock Properties Based on Electrical Resistivity Tomography (ERT) in Taebenu, Kupang, East Nusa Tenggara

Determining rock properties is very important for various needs in engineering design. It requires samples of soil and rock that are representative enough for laboratory test. The effort to obtain rock properties through laboratory testing is arduous, therefore, it is anticipated that geophysical technique may be able to ease the process without reducing the quality of data. This research aims to determine rock properties based on resistivity. The rock properties data (stength, wet density, moisture content) was obtained through laboratory test on soil and rock samples from a drilling activity, while the resistivity data was obtained by using geoelectric measurement at the drilling locations as the trajectories. There were 10 boreholes with the depths varying between 30-100 m, while geoelectric surveying depth of investigation reached to about 80 m with a 500 m trajectory. The research was conducted that the study area is covered with Quaternary deposits which are mainly consist of clay and pebble sediments. A statistical method was performed to analyze the relationship between rock properties and resistivity. The result shows that in Quaternary rocks, there is sufficient evidence to conclude that there are significant linear relationships between resistivity and strength as well as natural moisture content, but not for wet density. This approach to the relationship of resistivity and rock properties can be utilized in geotechnical analysis for various purposes. The results of this analysis can be used as a reference when carrying out any future geotechnical analysis by combining resistivity measurements within the same study area.