Finite Element Analysis of Rectangular Raft Foundation in Expansive Clay Soil

Abstract

Raft foundation is a combined footing that covers the entire area beneath a structure and supports all walls and columns. This paper presents the analysis of raft foundation in an expansive clay soil. Plaxis 3D computer software was used for the analysis. Deformations of the soil and the raft foundation at the initial, excavation and Loading stages were analyzed. The deformation of the clay was higher at the excavation stage with a value of 4.96*10-3 m, compared with 722.57*10-6 m recorded at the initial stage. With the introduction of modelled raft, the total deformation at this stage reduced to 712.22*10-6 m, with the raft serving as both stiffener and brace, plus loading rate efficiency of 96.2%. Under the same pressure, the deformation obtained using the classical Mohr-Coulomb model is higher than the one obtained using the Finite Element Analysis. Finite Element Analysis is therefore recommended for raft foundation analysis.