Effect of Foundation Depth on the Bearing Capacity of Square Footing of Soft Soil

Abstract

A recent study aimed to determine how the depth of a foundation affects the bearing capacity of a square footing on soft soil. The goal of the study was to provide critical soil parameters for constructing a stable and cost-effective foundation system for a one-story building with a basement. To evaluate the site's subsurface conditions, three bore holes (BH1-BH3) were drilled, each to a depth of 3 meters. The soil samples were then subjected to different tests, including triaxial, particle size distribution, Atterberg Limits, specific gravity, and moisture content tests. According to the study's findings, the bearing capacity of BH1 increased from 50 kN/m² to 53 kN/m² at depths of 1.0 to 3.0 meters. BH2's bearing capacity increased to 45 kN/m², 46 kN/m², and 47 kN/m² at depths of 1.0, 2.0, and 3.0 meters, respectively. BH3 showed a constant bearing capacity of 50 kN/m² at depths of 1.0 and 2.0 meters, with an increase to 51 kN/m² at 3.0 meters. In conclusion, the study showed that the depth of the foundation affects the bearing capacity of a square footing on soft soil. Based on the results, an isolated pad foundation with a bearing pressure not exceeding 45 kN/m² or a mat foundation satisfies the soft soil's stability requirements.