Combined VHM bearing capacity of pile leg-mat foundation on marine clay seabed

Abstract

The pile leg-mat foundation is a new type of jack-up wind power installation platform foundation. Since the foundation needs to bear the horizontal and bending moment loads caused by wind and waves for long period of time, the combined vertical, horizontal and moment (VHM) bearing capacity of the pile leg-mat foundation in the soft clay seabed is crucial in evaluating the safety of the jack-up platform. In this study, the effects of pile leg insertion depth L and the gradient of soil shear strength κ on the VHM bearing capacity of pile leg-mat foundation were analyzed. The numerical results indicate that the pile leg insertion depth significantly enhances the horizontal bearing capacity of the foundation. As the pile leg insertion depth increases, the horizontal load distribution of the foundation gradually shifts from the mat to the pile leg. However, the vertical and moment bearing capacity of the foundation is mainly provided by the mat and not significantly improved by the pile leg insertion depth. Based on the numerical results, the VHM failure envelope of the pile leg-mat foundation was established, and the method for assessing the bearing capacity of the pile-leg mat foundation was proposed.