Basal stability analysis of braced excavations in anisotropic and non-homogeneous undrained clay using streamline velocity fields

A basal heave stability analysis in anisotropic and non-homogeneous undrained clay by using the kinematic approach of limit analysis is presented. The proposed failure mechanism consists of four translational rigid blocks and a streamline-based shear zone. The velocity field for the shear zone, formulated by a streamline solution in a polar coordinate system, is a supplement to the previous streamline solution in rectangular coordinates. The present study is first verified by comparison with other existing solutions in homogeneous and isotropic soils. It is found that the streamline solution can produce sufficiently accurate upper-bounds compared with the multi-block mechanism, the finite element limit analysis and the shear strength reduction finite element method. Subsequently, validation of the streamline solution on basal stability in anisotropic and non-homogeneous clay is carried out by discussion on a well-documented case study.