investigation into geotechnical properties of clayey soils contaminated with gasoil using response surface methodology (rsm)

Oil and its derivatives such as gasoline, motor oil, and gasoil are being used in various industrial and non-industrial sectors as the main energy sources all over the world. unfortunately, in the processes of exploration, transportation, and storage, they may spill or leak into the soil. among them, gasoil, which is more widely used in different parts and machineries, has the largest contribution to contamination of the lands. purgation of these areas is not always feasible or possible. instead, they can be used in many engineering practices if the level of contamination is not high. in such cases, knowing the geotechnical properties of these areas is of great necessity and importance. in this study, extensive laboratory tests were performed on remolded clayey samples mixed with gasoil to evaluate their geotechnical properties. the response surface methodology (rsm) was used to analyze the data and find behavioral equations. according to testing results and rsm outputs, decrease in atterberg limits and increase in maximum dry density occur by increasing contamination. also, both of the shear strength parameters (c and f) exhibit a turning point at 8% gasoil content, while their variation trends are quite in opposite directions.