Most of soil structure interaction methods for analyzing large-section supports such as barrette foundation modeling and the surrounding soil are using 3D finite element (FE) models. In which, the model leads to a large finite element mesh, and consequently a large system of linear equations to be solved. In this paper, Composed Coefficient Technique (CCT) is adapted for analyzing barrette group. The technique considers the 3D full interactions between barrettes and the surrounding soil. Due to the high rigidity of the barrettes relative to the surrounding soil, a uniform settlement for the barrettes can be considered. This is done to compose the stiffness coefficients of the soil matrix into composed coefficients, which consequently leads to a significant reduction in the soil stiffness matrix. An application for analyzing barrette group by CCT technique is carried out on a real subsoil. The application presents guidelines and diagrams for barrette group that may be used in real practice.

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Classical analyses of barrette foundation taking into account full interactions between barrette and the surrounding soil leads to a huge barrette stiffness matrix. Consequently, a large system of linear equations must be solved, especially for analyzing barrette group and barrette raft. To overcome this problem, a Composed Coefficient Technique (CCT) is developed for analyzing barrette. In the analysis, the elasticity of the barrette body is considered using the finite element method, while that of the soil elements is considered using flexibility coefficients. The compatibility between the vertical displacements of the barrette and the soil settlements at the soil-barrette interface is taken in the vertical direction only. This assumption is that the external load on the barrette head, which is expected to be heavy load, is applied in the vertical direction. For comparative examinations, the barrette elasticity is determined using either 1D or 3D finite elements. A series of examinations is carried out to verify the application for analyzing barrette by CCT. It was found that, treating the barrette as an elastic body and representing the barrette by either 1D or 3D finite elements, gives nearly the same results.

In this paper, a numerical modification is carried out on the Layer Equation Method (LEM) of El Gendy and Herrmann to be applicable for analyzing 1-D consolidation of soft clay subjected to cyclic loading. The LEM is applicable for multilayered soil system subjected to variable initial stress along depth. The proposed solution is used for normally and over consolidated clays subjected to different types of cyclic loading considering the basis of the method of Toufigh and Ouria. The LEM is incorporated by the authors into the geotechnical software ELPLA and is verified with two verifications. The results of the verifications are close to the references results. The proposed solution is applied for circular storage tanks as a structure subjected to cyclic loading from filling and discharging cycles. An application was held to study the effect of cyclic loading on two zones located at Port-Said city in Egypt using real soil data from real sites. The results of the average degree of consolidation and consolidation settlement versus time are presented for both zones.