Transverse Isotropic Criterion Based on Generalized Nonlinear Strength

The geotechnical materials formed by natural deposition usually have transverse isotropic properties, and the transverse isotropic properties not only have a direct influence on the deformation of geotechnical materials but also have a nonnegligible influence on their strength characteristics. In order to reasonably consider the influence of transversal isotropic properties on strength properties, the soil's failure properties of complete isotropic and transversal isotropic soils were compared. At the same time, a hypothesis was adopted, that is, at the failure moment, the ratios of principal stresses corresponding to completely isotropic soil and transverse anisotropic soil had linear relationships to each other, and the ratio coefficient β was assumed to be a transverse isotropic parameter. The proposed parameter β was utilized to reflect the influence law of the original anisotropy on the shape of the failure curve on the deviatoric plane. The proposed parameters were employed to reflect the influence law of the original anisotropy on the shape of the failure curve on the deviatoric plane. For the relationship between the isotropic criterion and the transversal isotropic criterion, a kind of β transformation method is proposed, which can realize the transformation of isotropic stress space and transversal isotropic stress space. Based on the isotropic generalized nonlinear strength criterion (GNSC), the method of determining the transverse isotropic parameter β is given by making use of the condition that the shape parameters $\overline{\alpha }$ and α of GNSC in the isotropic stress space and the transverse isotropic stress space, respectively, are exactly the same. By comparing the strength test data under different Lode angles with the predicted results of the generalized nonlinear criterion of transverse anisotropy, the results showed that the proposed anisotropy criterion can simply and accurately reflect the failure law of the geotechnical materials under the true triaxial loading condition.