Numerical analysis of bearing capacity of multiple strip footing on unreinforced and reinforced sand beds

In this paper, the ultimate bearing capacity of multiple strip footings on reinforced and unreinforced sand beds is investigated using finite element method. The study utilizes efficiency factor to assess the change in the ultimate bearing capacity due to footing interference. The impacts of angle of internal friction, clear footing spacing and number of reinforcement layers on the efficiency factor are presented and evaluated. In addition, the effect of dilatancy angle and stress distribution in soil-reinforcement system is examined. The developed numerical model was verified against available theoretical and experimental data from literature prior to its use in this study. It is noted that for both reinforced and unreinforced sand, the ultimate bearing capacity of strip footings in a group is always greater than that of a single footing when the footing spacing is less than twice the footing width. Furthermore, the efficiency factor was found to increase as the footing spacing decreased and as the number of reinforcement layers increased. The degree of enhancement in ultimate capacity is, therefore, dependent on the angle of internal friction and number of reinforcement layers. The paper also proposes and assesses the use of alternative approach to modelling the effect of reinforcement using an apparent cohesion to reflect the addition of reinforcement layer. The use of apparent cohesion seems reasonable but further investigations would be required.