Experimental investigation on interaction problem of two nearby circular footings on layered cohesionless soil

Abstract

In the present investigation, the interaction between two nearby surface circular footings are determined by conducting a number of laboratory scaled model tests on a dry, cohesionless Ennore sand bed. The load-settlement curves for closely spaced circular footings of different sizes are obtained to study the interference effect between two footings. The effect of clear spacing (S) between the footings on the bearing capacity and settlement of interacting footings is studied. The experimental study indicates that the bearing capacity of single isolated footing on double layer soil deposit decreases with increase in the depth of top weak layer. A significant change in the bearing capacity and settlement of the interfering footing is observed in single as well as double layer soil deposit. Irrespective of the type of deposit, the ultimate bearing capacity of interfering footing increases with the decrease in the spacing between the footings. The settlement behaviour of the interfering footing at the ultimate failure is also studied, which follows the same trend as the bearing capacity. Finally, the results in term of efficiency factors (ξ_γ, ξ_δ) are presented and their variation is computed with respect to the change in the clear spacing (S) between two footings. The present experimental observations are compared with the results available in the literature.

Keywords:

• layered soil
• interference effect
• circular footing
• bearing capacity
• model test

Acknowledgments

Priyanka Ghosh would like to acknowledge the financial support provided by the Department of Science and Technology (DST), India to carry out the present work through a sponsored research project.