Numerical limit analysis of the ultimate load bearing capacity of a pier foundation under complex load

Abstract

A pier foundation has plenty of advantages as the foundation form for large onshore wind turbines in the terrain of the Gobi desert and collapsible loess areas. The ultimate load bearing capacity design, as an important part in the design phase of this foundation form, is not sufficiently in terms of design theory and the checking method, especially for application in collapsible loess areas. In this paper, numerical limit analysis has been employed to analyze the load bearing capacity for the scheme of selection of a pier foundation of a 100 MW wind farm in certain collapsible loess geology in Ningxia. The results were then compared with the empirical formulas, the limit equilibrium solutions and the finite element solutions to verify the accuracy of the results. It has been demonstrated that under the ultimate engineering load, the pier foundation can meet the stability requirement. In the ultimate state, whether the surrounding soil of the foundation falls in plasticity is associated with the ratio of the depth to the diameter of the foundation. The numerical limit analysis method can automatically determine the failure surface.