Abstract: Based on the reconstruction project of Tianjin-Tanggu Expressway, the subgrade bearing capacity of composite foundation with pipe piles is calculated. The Terzaghi's theory is verified, and the Terzaghi's theoretical formula is modified for application in composite pipe piles. Through the analysis of the typical elements, the stress model of pile-soil under rigid foundation is derived. Finally, it is demonstrated that the results from this solution are in accordance with the design ones of a project. So the proposed method can reflect the working behaviors of foundation treatment of pipes pile in Tianjin area. It supplements the application of composite foundation with pipe piles and prospects for the model.