Dynamic analysis of PCC pile composite foundation under train vibration load

As a new type structure form in soft soil foundation treatment,PCC pile-net composite foundation has been used in high speed railway construction in soft soil area.The dynamic characteristics of PPC pile composite foundation under the train vibration load is worth studying.A reasonable train dynamic loading form is determined in this paper.A three-dimensional dynamic coupling finite element model of tracks-embankment-pile-soil composite foundation is established using software ABAQUS.The dynamic characteristics of embankment,pile and foundation soil are studied based on the modulus changes of foundation bed,pile,cushion layer and foundation.The results show that the dynamic response of PCC pile composite foundation is different from the solid pile;the reflection overlap effect of dynamic stress occurs in the pile.The dynamic interaction of pile and cushion layer is greater than that of soil and cushion layer.The modulus changes of foundation bed don't affect the dynamic stress of pile-soil seriously.The dynamic load sharing ratio of the pile body increases with the increasing of the cushion stiffness.Meanwhile,the increase in modulus of the cushion enhances the dynamic stress of the pile top,which is due to dynamic deformation coordination occurring between piles and cushion.The increase in modulus of the pile enhances the dynamic stress of the pile and increases the propagation speed of dynamic stress.The PCC pile can bear most of the dynamic load and reduce the dynamic load of the soil,thus reduce the influence of upper load on composite foundation effectively.As the distance increases with the center pile,the dynamic stress of the side pile decreases.