DEM analysis of installation and bearing process of open-ended piles considering plugging effects

The penetration process of open-ended piles will cause complex plugging effects, which further influence the installation and bearing characteristics of piles. Considering the high cost, long period and limitations in reflecting the interaction between piles and soil plugs of the traditional experimental approach, the jacking installation and subsequent loading process of open-ended piles in sand are simulated based on the discrete element method (DEM). The periodic cell replication method is used to generate a homogeneous foundation sample with linear stress distribution. Based on the analysis of the soil deformation characteristics, the characteristics of the active arch and passive arch distribution of the soil plugs are revealed. Based on the analysis of the evolution of soil plugging parameters and plug bearing characteristics, it is found that the incremental filling ratio (IFR) is more sensitive to the plug behavior, and the development of plug resistance shows good consistency with the trend of the IFR value. Also, the open-ended piles are in the fully plugged mode under the static loads, and the load-displacement response of soil plugs is elastic-plastic. Finally, the method for calculating the end bearing capacity of open-ended jacked piles is established by considering the CPT cone resistances, plugging effects and pile size effects. The above results reveal the evolution process and bearing mechanism of soil plugs and can provide reference value for the prediction of installation resistance and calculation of bearing capacity of open-ended piles considering soil plugging effects.