A 1-D model to describe the suction anchor–soil plug interaction under sustained uplift loads

We present a one-dimensional model, based on displacement compatibility and continuity of the water mass equations, to describe the mechanical and hydraulic interaction at the contact between the caisson lid and the soil plug during the uplift process of a suction caisson. The model has been specifically conceived as an alternative to the technique based on the use of a layer of poroelastic FE, widely presented in the literature and referred to as water elements. The proposed model, which depends on two parameters having a clear physical meaning, has been encoded in a Fortran-based UAMP subroutine and used in an incremental FE procedure to simulate the progressive sliding failure of a caisson under sustained loads. The results, which are in very good agreement with previous numerical studies based on the use of the water elements, are also compared with those obtained from a simplified numerical approach, in which a bonded lid–plug contact is considered. The comparison is presented to further assess the effectiveness of the proposed 1-D model and to highlight the limitations of the simplified method, clarifying the extent to which these simplifications can be deemed acceptable for engineering purposes.