Soft soil properties of the model.

The study presents state-of-the-art requirements verification process for the prediction of the stability of the multi-staged deep excavation in submerged soft soil retained by stell sheet pile walls structures applied at the development of elasto-plastic finite element calculation method performed from Cast3M and Plaxis FE codes. Optimization numerical calculation results are proposed for retained walls design and construction on the basis of the horizontal displacement, earth and water pressures measurements. The transformation of the geometry and stiffness of the stell sheet pile walls to the retaining walls of an equivalent bending stiffness on the one hand and regular geometric shapes allowed in this paper to overcome the difficulties of modelling these stell sheet pile walls in 2D with irregular shapes. The horizontal deflection of the wall, the vertical displacement behind the walls, and the settlement of the excavation bottom are given. They have been compared by those obtained by various authors around the world. The results of this approach are satisfactory in view of the horizontal displacement curves obtained on the stell sheet pile walls compared by the measures.