Enhancement of Oil-Contaminated Sand Bearing Capacity Using Floating Stone Columns Inclusions

This paper presents the results of small-scale models and finite element analysis to investigate the performance of shallow footings resting on oil-contaminated sand enhanced by stone columns inclusion. The columns float in the contaminated sand and are tested at 3, 6 and 9% oil content. The results show that the bearing capacity of contaminated sand without stone column inclusions reduces by 7, 25 and 33% for 3, 6 and 9% oil content, respectively. Using stone column inclusions increases the bearing capacity by 46, 64 and 76% for 3, 6 and 9% oil content, respectively. End bearing stone columns are, also, tested at the same oil content and increases the bearing capacity by 79, 100 and 112% for 3, 6 and 9% OC, respectively, and about 23% greater than the floating system. Also, the stress concentration factor is calculated from finite element results, which vary from 3.40 to 4.52, and the corresponding stress concentration ratio (stress in column/Stress in soil) varies from 2.0 to 2.67 for all oil content and column lengths. Moreover, the critical column length of the floating models is 6 times the column diameter for 3 and 6% oil content and 9 times the column diameter for 9% oil content. Furthermore, the failure mechanism is defined based on the critical length, which shows that the punching mode controls the behavior for column lengths less than 6 diameters, and bulging failure is obvious for column lengths more than 6 diameters.