Analysis on Deformation Mechanism of PCC Pile Composite Foundation Under Train Vibration Load

In this paper, a three-dimensional dynamic coupling finite element model of tracks of embankment pile-soil composite foundation has been established. The dynamic displacement of pile composite foundation is analyzed based on modulus parameter changes of foundation bed, pile, cushion layer and foundation. The results show that the interface area between cushion and pile increases with the decreasing of pipe pile top, the load-sharing ratio of the PCC pile increases significantly, and the load that the soil bears also decreases. The magnitude and scope of dynamic displacement for subgrade also decreases. It is worth noting that the dynamic interaction between PCC piles and cushion layer is greater than that between soils and the cushion layer. Rigid piles tend to penetrate into the cushion layer; the dynamic curve along the cushion layer surface is similar to type 'W'. An increase in modulus of the cushion enhances the dynamic interaction effects between PCC pile and the cushion, which, to some degree, encourages PCC piles to share more bearing responsibilities. This mechanism magnifies the dynamic displacement of pile top and body, whilst simultaneously reducing upward penetration deformations.