Interference effect of two nearby strip surface footings on cohesionless layered soil

In this study, a number of model tests were conducted to study the interference effect of two near-by strip footings on dry, cohesionless, layered soil. The single as well as two-layer foundation bed was prepared by using Ennore sand. Two different widths (75 and 50 mm) of model footing were employed in the study. To study the interference effect between two footings, first, the bearing capacity of single isolated footing was obtained and later on, that of closely spaced footings was determined. The experimental study indicates that the bearing capacity of single footing on the layered deposit decreases with increase in D/B, where D and B are the depth of top weak layer and width of footing, respectively. The effect of centre to centre spacing (S) between two footings, on their bearing capacity and settlement at failure is mainly focused in this paper. The settlement behavior of closely spaced footings is found to follow the same trend as the bearing capacity. The results are presented in terms of efficiency factors (xi(gamma), xi(delta)) and their variation was obtained with the change in S. The present experimental observations are generally found in good agreement to those theoretical and experimental results available in the literature.