A detailed parametric study based on linear-elastic three-dimensional finite element (FE) analysis with proper raft-soil interaction is performed for different types of rafts (rectangular, square, circular, and strip) by varying the different soil and structural parameters such as Young's modulus and Poisson's ratio of soil, the aspect ratio of the raft, the thickness of the raft, and Young's modulus of the raft. It is observed that the average subgrade stiffness of a raft increases with the increase in raft slenderness ratio, decrease in Poisson's ratio of soil, and increase in modulus ratio of raft and soil. The variation of subgrade stiffness at various points of the raft is also studied and observed that it is influenced by the raft-soil interactions. A Closed-form fitted equation is developed for estimation of average raft settlement based on parametric influence study on average settlement of rafts and raft-soil interactions, using the least square method of regression analysis. The precision of the proposed method is checked by comparing with FE analysis results, some case studies, and existing numerical methods. The superiority of the proposed method lies in the fact that it effectively captures the effects of raft-soil interaction and flexibility of the raft. The proposed method will be useful in predicting the settlement behavior of a raft similar to the type of rafts considered in the present study at the initial design stage.
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