A Method for Nonlinear Analysis of Raft Resting on Multilayered Heterogeneous Soils

Abstract

This paper presents a new method for the nonlinear analysis of rafts resting on multilayered heterogeneous soils using the Vlasov model. The finite-element and the finite-difference methods are employed to solve the governing differential equations for the flexure of the raft and the displacement within the supporting soil mass, respectively. The soil heterogeneity in the vertical direction or in the horizontal directions within each soil layer is considered, and the soil nonlinearity is taken into account through the reduction of the soil shear modulus as a function of strains within the supporting soil mass. Through a comprehensive comparative study, it is found that the present method is validated as reasonable by field measurements and is in good agreement with nonlinear three-dimensional finite-element analysis and other existing analysis methods. A study is carried out to investigate the effect of soil layering, soil nonlinearity, and soil heterogeneity in the vertical direction and in horizontal directions on the raft behavior. It is concluded that neglecting the real conditions of the supporting soils (e.g., soil layering, soil nonlinearity, and soil heterogeneities in the vertical or in horizontal directions) in the analysis of the soil–raft interaction leads to an unrealistic prediction of the raft behavior.