Effect of the oil spill on the soil friction angle

Abstract

Abstract There are many factors governs the soil stability, and strength is one of the most important aspects. In the event of soil contamination by oil spills, the soil characteristic and its physical properties will change due to the intrusion of oil in the subsurface. This changes mainly related to the viscous properties of the oil in comparable to natural groundwater. As the soil friction angle is one of the main components of the soil shear strength, the viscosity of the oil will affect the soil friction angle. In this study, three types of typical sand were used to mix with water and oil, and the soil friction angle is determined using direct shear test on these samples under dried condition, 50% of soil saturation and at optimum moisture content. The three sand is classified as Sandy clay, Silt clay with sand and Silt with sand. It is found all samples followed soil compaction principal when the sample mixed with water or oil, except for Sandy clay soil. For sandy clay, as the soil friction angle supposed to increase when reaching the optimum moisture content (φ = 38.7°), the soil friction angle is continued to reduce (φ = 34.2°). This may due to less than 60% coarse grain of the grain size distribution in sandy clay. As coarse grain is the main factor for the grain angularity function that provides the interlocking between particles.