At present, the theory of cavity expansion applied to pipe piles is mostly limited to the assumption of isotropic soil. However, the natural sedimentary site has strong anisotropy, which has an nonnegligible influence on the deformation and failure characteristics of stratum soil. (1) The proposed Von-Matsuoka-Lade(VML) strength criterion is used to describe the failure and yield characteristics of clay, sand and rock. (2) The fabric tensor is introduced to describe the anisotropic properties of clay, and the joint stress tensor is derived based on the isotropic representation of the anisotropic properties. The joint stress tensor Rij is used to represent the isotropic stress space. By mapping the VML criterion in the ordinary stress space to the Von-Mises criterion in the Rij space, the transformed stress method reflecting the anisotropy property can be established. (3) The Unified hardening (UH) model is generalized based on the above anisotropic transform stress method, and the corresponding constitutive equation is derived. (4) Based on the self-similar property of soil deformation around pipe pile in the formation, a new self-similar property solution is proposed and the corresponding radial strain and tangential strain are obtained according to the assumption of radial displacement during pipe pile pressing into the formation, and a new anisotropic soil stress analysis equation reflecting pipe pile static pressing into the formation is obtained by combining with the constitutive equation. The analysis and comparison with the experimental data show that the proposed method of soil stress analysis in anisotropic strata is reasonable and applicable.
