Foundation Breadth Influence on Settlement Response of Clayey Soil

Abstract

The response of clayey soil settlement influenced by varying foundation breadth has been investigated. The objective of the research was to determine the settlement response of the soil when loaded with different foundation breadth, aimed at developing stable and cost-effective foundation systems for structures. Eight boreholes, labeled BH 1 to BH 8, were excavated to a depth of 3 meters. Soil samples were then analyzed through various index property tests, which included particle size distribution, specific gravity, moisture content, and Atterberg Limits tests. Classification tests indicated that the soil primarily comprises very soft to soft, brown to grey inorganic sandy lean clays and sandy silts, both exhibiting low plasticity, to a depth of 3 meters from the ground surface. The gradual dissipation of excess pore water pressure in the soil samples from boreholes BH 1 to BH 8 was assessed through a one-dimensional consolidation test. The saturated test specimen underwent incremental loading over time. The analyzed test results enabled the evaluation of the coefficient of volumetric compressibility (m_v) based on the respective void ratio about pressure values. A total consolidation settlement (P_c) was calculated for foundation breadth (B) ranging from 0.8 to 1.6 meters, utilizing an m_v value of 0.92 m²/MN, which aligns with the established net allowable bearing capacity of 35.26 kN/m² for the site, in the settlement analysis. The findings indicated that an increase in foundation breadth led to an increase in settlement, which varied from 9 to 51 mm for foundation breadth between 0.8 and 1.6 m. The saturation of the clayey soil increased pore water pressure, which ultimately caused greater settlement. In summary, the research demonstrated that the breadth of the foundation affects the settlement behavior of clayey soil. According to the findings, an isolated pad foundation with a bearing pressure below 35.26 kN/m² meets the settlement criteria for the soil.