Axial Bearing Calculation of Synchronous Concentric Steel Pipe-Cement Soil Composite Piles

The synchronous concentric construction of steel pipe-cement soil composite pile consists of steel pipe pile, inner cement-soil, and outer cement-soil. Its axial bearing behavior is closely related to the interactions between the three components and the surrounding soils, and its bearing and deformation mechanisms are very complex. Based on site excavation tests, the inner cement-soil and steel pipe pile were simplified into equivalent modulus solid piles by area. An elastic failure model was used to simulate the interaction between the steel pipe pile and the outer cement soil interface. The deformation of the outer cement soil and surrounding soil was considered as shear deformation, and the relationship between the pile end resistance and settlement was analyzed using a bilinear model. Taking into account the deformation characteristics of the steel pipe pile, cement-soil, and surrounding soil, the axial bearing capacity and deformation calculation formula of this new composite pile were derived, and the methods for determining the values of relevant parameters were provided. The feasibility of the above proposed method was verified through comparative analysis of engineering examples.