Physical Modelling of Axial Compressive Bearing Capacity of Instrumented Piles in Oil-Contaminated Sandy Soil

Abstract

Oil and its derivatives such as gasoline, gasoil and ‎kerosene are the main sources of energy in the transport and industry sectors, and also the most common ‎soil contaminants. Oil contamination of the soils as a serious geoenvironmental problem not only affects soil quality ‎but also changes its geotechnical properties. Any changes in the geotechnical properties of the soils affect the axial bearing capacity of pile. The main objective of the current study is to determine the effects of various concentrations of different oil ‎products, as well as different soil relative densities, and thickness of the contaminated sand layer on the load–displacement (axial compressive) behaviour of two ‎instrumented, close-ended steel pipe piles with different diameters and slenderness ratios implemented in an oil-contaminated sandy soil through physical modelling. Tests results were compared with the CFEM ‎analytical method of calculating pile axial bearing capacities. Results showed that increasing the percentage of the oil in the soil reduces the values of net total, toe and shaft bearing ‎capacity of the pile. The type of the oil had a remarkable effect on the bearing capacities of the pile. The higher the kinematic ‎viscosity, the lower the amount of bearing capacities. ‎Comparing the measured and predicted values of bearing capacity based on modified CFEM ‎method concluded that, although a good agreement can be seen between the results of shaft capacity, the ‎CFEM method with modified bearing capacity factors could not predict the effects of oil contamination ‎on the toe bearing capacities of piles precisely.