Study on the Behavior of Surface Foundations resting on Lateral Confined Sand Bed

The behavior of circular surface foundations resting on sand, surrounded by peripheral skirt was studied by numerical analysis. The performance of skirted foundations was analyzed by evaluating the effect of different parameters and compared with the results of semi-deep and embedded foundations in the depths of skirt tip. The effect of lateral sand confinement on foundations behavior was evaluated by examining the parameters of foundation width, sand shear strength, skirt depth, and surface roughness. The results of numerical analysis were compared with small-scale physical modeling data. The results showed that the vertical bearing capacity of surface foundations due to lateral confinement, significantly increased and the settlement also decreased. The skirt existence causes resistance to soil lateral displacement and leads to a significant improvement in the response of the foundation. The improvement values increased with increasing skirt depth and decreasing sand shear strength. Depending on the different parameters, bearing capacity of skirted foundations increased by about 1.8 to 3.3 times, and settlement values reduced up to 54% those of surface foundations. Comparison of the results showed that the values of bearing capacity and settlement of skirted foundations are close to those of pier foundations with the same depth and width.