Influence of skirt on pressure-settlement response of shallow foundation in cohesionless soil

The provision of skirt improves the bearing capacity of conventional shallow foundation by confining the soil and transferring the superstructure load to the deeper strata; however, the role of governing parameters remains inadequately explored. This study investigates the improvement in the pressure-settlement performance of the skirted foundation through physical model tests at 1-g scale. The contribution of skirt beneath the vertically loaded shallow foundation is evaluated attributing a variety of influential system parameters such as depth ratio of skirt (Ds/B), normalized offset distance (y/B) and soil relative density (RD). This study presents a novel investigation into how the relative offset distance between the model foundation and the skirt periphery influences the foundation response, providing new insights for optimized skirted foundation design in cohesionless soils. Results are presented in the form of dimensionless parameters such as the Improvement Factor (IF) and Settlement Reduction Factor (SRF). The results indicate that the skirting of the foundation improves the bearing capacity by a factor of approximately 1.25 and reduces the settlement by a factor in the range of 0.69-0.74. The reduction in normalized offset distance from 1.00 to 0.25 reduces the foundation settlement by a factor in the range of 0.85-0.88 to 0.66-0.74. Additionally, the study demonstrates that the effect of skirting is insignificant under dense soil conditions (70% RD). The results obtained from experimental investigation have been validated with the analytical solutions in this study. The findings of this study are pertinent to subgrade, foundation, and pavement stabilization in cohesionless soils.