Semianalytical Solution for the Uplift Bearing Capacity of Spread Foundations in Sand

Abstract

An innovative semianalytical solution was introduced to accurately assess the uplift bearing capacity of spread foundations in sand, which is important for the design of transmission towers. The research addresses the shortcomings of previous analyses, which relied on a 1g laboratory test and consequently overestimated uplift bearing capacities due to scale effects. To overcome these limitations, a series of centrifuge tests were conducted under stress conditions representative of field conditions. The test results led to the identification of a bilinear failure surface, effectively capturing distinct uplift failure mechanisms along the embedment depth, including a passive mode near the ground surface and an active mode downward. A novel application of genetic programming analysis, based on symbolic regression techniques, was employed to optimize the determination of parameters forming the bilinear failure surface. The net uplift bearing capacity corresponding to the bilinear failure surface was evaluated using a limit equilibrium approach combined with a slice procedure. The proposed semianalytical solution was validated with both the current test results and previously published data, illustrating its reasonable applicability and representing a significant innovation in determining the net capacity of spread foundations in sand.