Influence of Footing Size and Shape on Undrained Bearing Pressure of Normally Consolidated Ground
摘要
The stability and performance of structures are determined by the bearing capacity of foundations, which is mostly estimated considering the soil strata as homogeneous. Undrained bearing capacity of footing resting on homogeneous cohesive soil is independent of the footing size. In contrast, the depth of influence for different shapes of footings depends on their size. Larger footings resting on normally consolidated soils transfer the load over greater depths of varying strength, influencing its bearing capacity. This study analyzes the response of strip and circular footings of different sizes resting on normally consolidated soils, whose undrained shear strength increases with depth. Finite element analysis evaluates the bearing pressure-settlement responses of footings of various sizes and shapes (circular and strip) resting on normally consolidated soils. Results show that undrained bearing pressure increases with the nonhomogeneity rate of strength with depth, in the case of both strip and circular footings, unlike the case with homogeneous soils. For a given size, strip footings exhibit more bearing pressures than circular footings. Increments in bearing pressure with the degree of nonhomogeneity of undrained strength with depth are more significant for strip footings than those for circular footings. Bearing capacity factors are presented as a function of footing size and rate at which undrained strength increases with depth (degree of nonhomogeneity) for strip and circular footings.