Abstract: Determination of the ultimate uplift capacity for tension piles play a dominant role in engineering design.Unfortunately,due to the limitation of in-situ test conditions,it is almost impossible to obtain the ultimate uplift capacity of tension piles under deep excavation from field tests,and the theoretical study becomes the only feasible way to solve this problem.Adopting the Coulomb friction model for the pile-soil interface with direct constraints,two full-scale field tests on single uplift pile with uniform cross-section and enlarged head were simulated by employing the elastoplastic finite element method,and the simulated results were in good accordance with the field test data.Based on the above-mentioned analysis approach and calculation parameters,the difference between the uniform cross-section piles and the belled piles was examined and a comprehensive study focusing on the effects of excavation width and embedment depth was performed.Finally,suggestions for determining the ultimate uplift capacity of tension piles under deep excavation were given.