Alireza Shahnamnia - Department of Civil Engineering Najafadad Branch , Islamic AzadUniversity,Najafabad, Iran
Masoud Mirmohammad Sadeghi - Department of water Engineering ,Niroo Research Institute (NRE), Isfahan HigherEducation and Research Institute (IHEARI), Isfahan, Iran
Seyed Mahdi Hejazi - Department of Textile Engineering, Isfahan University of Technology, Isfahan, Iran
SayedMahdi Abtahi - Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran

Oil-contaminated soil is detrimental to the ecosystem. There are various methods for purifying and controlling oil-contaminated soil. Among these, the use of oil absorbent geotextiles is considered a new method, and its performance requires more research. The separating by geotextiles has the advantages such as absence of chemicals in the separation process, less energy, simple control and implementation. This study presents an environmentally friendly sustainable solution using spacer geotextile layers to absorb crude oil and improve the geotechnical properties of contaminated soil. The variables include contamination percentage, number of fibrous substrate layers, soil overhead load pressure and duration of exposure to contaminated soil. The response variable is the internal friction angle of soil obtained from the direct shear test. By comparing soil samples containing geotextiles with samples without geotextiles, it was concluded that spacer geotextile layers could increase the internal friction angle of the soil and thus lead to improved soil properties. Increasing the number of geotextile layers, loading and the presence time of geotextile layers in the soil had increased the internal friction angle. But as the oil percentage in the soil increases, the internal friction angle of the soil decreases. Also, in this study, a linear regression model has been used to investigate the effect of existing parameters and the model was in good agreement with the experimental data.

Oil-contaminated soil; Geotextiles; Separation; Density; Direct shear tests