Numerical analysis of deformation behaviors of underpinning piles during excavation

The finite element method is used to analyze the effects of excavation on the behaviors of underpinning piles in excavation area. First, numerical model is adopted to simulates the interaction of structure-foundation-soil and estimate negative effects of the rebound deformation of underpinning piles on the top plate. Based on the deformation and bearing state of the underpinning piles, the adjusting deformation from oil jack is available. It is demonstrated that a constant level of load should be applied to the top of the underpinning piles so that the top plate has the “zero” additional deformation. During the process of loading adjustment, the axial force at the upper part of the underpinning pile increases and the axial force at the lower part decreases as the depth of excavation increases gradually. When the depth of excavation is over 5 meters, negative skin friction occurs at the lower part of pile and results at the axial tension in the bottom. |