Interference effect of shallow foundations constructed on sand reinforced with geosynthetics

This paper numerically examines the bearing capacity ratio for rough square footings located at the surface of a homogeneous sandy soil reinforced with a geogrid. The failure stage in the sand was controlled using the Mohr–Coulomb criterion and a non-associated flow rule. Numerical results were compared with those obtained from other experiments and were found to be in good agreement. A parametric study revealed the role of the distance between reinforcing layers and footings and the width and depth of reinforcing layers on the bearing capacity. The distribution of shear strain and displacement in the soil for both reinforced and unreinforced footings was investigated. In short, the results showed that the bearing capacity of interfering footing increases with the use of geogrid layers, depending on the distance between two footings. The best geometry and orientation of the geogrid layers were determined to achieve maximum bearing capacity for closely spaced square footings. Parametric studies demonstrated that the efficiency of reinforcement on the bearing capacity of interfering footings is greater than that on an isolated reinforced footing. In addition, reinforcement caused the bearing capacity of interfering footings to increase by about 1.5 and 2 for one and two reinforcement layers, respectively. Design charts are presented.