Numerical analysis of the boundary effect in model tests for single pile under lateral load

Model tests of pile foundations have been widely used to assess tlateral bearing capacities. The difference between the measured and the real lateral bearing capacity of pile foundation may exist due to the boundary effect, and this issue has not been studied thoroughly in the past. This paper, therefore, describes an extensive investigation of the boundary effect of a model container on the lateral bearing capacity of a circular pile foundation in uniform clay through finite element (FE) analysis. Prior to parametric study, the FE model was validated by comparing with the centrifuge test results and good agreement was obtained. Based on the parametric study, including various container sizes and soil properties, it can be concluded that the boundary effect on circular pile lateral bearing capacity can be significantly eliminated when the distance of container boundary to the pile center is larger than 15 times the pile diameter. A formula was proposed, based on FE results, to predict the difference of lateral bearing capacity of a circular pile in uniform clay induced by the boundary effect.