ABSTRACT
Crude oil leakage to the soils from facilities related to the oil industry can cause destructive environmental pollution effects. Additionally, oil contamination may also alter the mechanical characteristics of geomaterials such as shear strength behaviour which is requisite for assessment of numerous engineering problems. In the past, limited researches have been done to analyze the shear strength behaviour of oil contaminated soils while major of them were carried out in the saturated state. The objective of this research is to study the shear strength behaviour of polluted porous soil media both in saturated and unsaturated conditions. For this, a clayey-sand and one type of crude oil were selected, and a series of direct shear tests were carried out in saturated and unsaturated conditions. The contaminated samples were prepared by mixing the soil with 6% crude oil. Unsaturated direct shear tests were performed in the initial matrix suction of 30 kPa on specimens by using a novel unsaturated direct shear apparatus designed and built in Tarbiat Modares University, Iran. The results indicate an increase in the shear strength and cohesion and a slight reduction in internal friction angle of crude oil contaminated specimens while oil contamination content is increased.
