Abstract: With the rapid development of China's high-speed railway, it is common that the proposed railway bridges cross the existing railway alignments. As the piled foundations are extensively used in the railway projects, the influence of the proposed piled bridge foundations on the existing pile supported footings has become one of the concerned topics in the pile foundation engineering practice. How to evaluate the impact of the proposed piled foundations on the existing footings is a critical engineering issue. In this paper, using a practical engineering background, a threedimensional numerical model is established by using software OpenSees, which is an open source finite element analysis platform. The multiyield surface elastoplastic constitutive model was used for soils and the pile foundation was simulated by the elastic beamcolumn element. Through the response of the axial force and displacement, the influence of the proposed piled foundation on the existing footing structure was evaluated. The numerical results show that: (1) when the distance between the proposed piled foundation and the existing footing is 9.71 m, the proposed piled foundation has an obvious influence on the axial force of the existing piles, which increases the axial force in the existing pile foundation by 25%; (2) The proposed piled foundation has a certain influence on the displacement of the existing deep foundations, and has the greatest influence on the vertical displacement of the existing footings, among other factors. This influence increases the vertical displacement at the existing pile foundation by up to 45%. The numerical analysis results provide could a guide and reference for the study of the similar engineering projects.

Key words: railway bridges, piled foundations for bridges, pile groups, three-dimensional finite element analysis, numerical simulation