Abstract: DX pile has a remarkable potential in uplift application. Comparing with the ordinary piles, the uplift failure mechanism of DX pile is discussed. Then the mechanism of loading transfer during uplift and the development of uplift friction on the main pile sides and on the branches of DX pile with depth are analyzed in detail. According to the structures of DX piles and the effects of the main-pile-side-friction and the soil-friction around the branches of DX piles, the equilibrium equation of DX piles’ uplift capacity in limiting conditions are deduced. After that, the calculation formula for uplift-bearing capacity of DX pile is drawn. Before presenting the design method and design procedure of DX piles, the related theoretical and experimental methods to decide the formula’s parameters are discussed. Finally, qualitative analysis of the major factors, such as the soil strength, the number of branches, the distances between adjacent braches and the angle between the surface of branches and the horizontal level, which will affect the uplift-bearing capacity of DX piles, are carried out.

Key words: pile foundation, DX pile, uplift, load transfer, load-bearing mechanism