The crude oil leakage in soils could lead to an extreme reduction in resistance. It is significant for oil-rich countries, such as Iran, with several crude oil resources. The clean and oil-contaminated Bushehr carbonate coastal sand cyclic simple shear behavior is investigated. The clean and crude oil-contaminated sands were prepared with a relative density of 60%, and oil-contaminated samples were prepared using 2%, 4%, and 6% crude oil. Shear modulus (G) and damping ratio (D) rely on soil particle characteristics. Using 2% crude in Bushehr carbonate sand leads to an approximately 5% increase in shear modulus. Also, applying 4% oil in the specimens caused roughly 8% enhancement in the dynamic strength of Bushehr carbonate sand. Keeping the conditions constant, the effects of oil contamination on this carbonate sand were investigated using a cyclic simple shear apparatus. The results indicate that 6% crude oil contamination will lead to a decline in shear modulus (10.6%), a growth (27.6%) in the damping ratio, and a decrease (16.6%) in the friction angle of Bushehr sand in comparison to clean sands. However, 2% and 4% contamination led to static and dynamic resistance increase of Bushehr carbonate sand. The results indicated that using 2% and 4% crude oil caused a 12.5% and 20.8% increase in the static resilience of Bushehr carbonate sand, respectively.
