Behavior of Oil-Contaminated Sands in CBR Test

Several factors affect the bearing the load of natural and engineered embankments and slopes including the crude oil leakage, leading to a severe decrease in resistance. This is especially important for oil-rich countries, such as Iran, which have several crude oil resources. The main purpose of this study is to investigate the load bearing the load (i.e. load versus settlement) and strain-stress behavior of crude oil contaminated sandy soils using California Bearing Ratio (CBR) Test. In this paper, 10 different types of sand with different characteristics used. At first, a series of CBR experiments performed for natural sands (i.e. clean sands) and then contaminated sands with 6% crude oil tested under similar conditions and densities to obtain the reduction in bearing the load of crude oil contaminated sands quantitatively. Experimental results showed that bearing the load of sand containing 6% of crude oil decreased at least 50% compared to clean sands and the stress-strain diagram of these contaminated soils would decrease significantly. Based on the results of investigation, it can be stated that particle shape(sharpness or roundness), coarse particle ratio,and finally the type of aggregation influences the resistance of crude oil contaminated sands. It was also found that standard Ottawa sand had 83% reduction in strength and sand with a coarse particle had 57% decrease in strength. Sand contaminated with crude oil experience a severe loss of bearing capacity,so in designing foundations and engineering structures, greater safety factors should be considered, where there is a risk of crude oil leakage.