ELASTIC-ANALYSIS OF SOIL-FOUNDATION INTERACTION

Abstract

Over the years, many methods have been developed to predict the settlement of shallow foundations on cohesionless soil. However, methods for making such predictions with the required degree of accuracy and consistency have not yet been developed. Accurate prediction of settlement is essential since settlement, rather than bearing capacity, generally controls foundation design. The settlement of foundations under working load conditions is an important design consideration. Well-designed foundations induce stress-strain states in the soil that are neither in the linear elastic range nor in the range usually associated with perfect plasticity. In this study, we analyze the load-settlement response of vertically loaded footings placed in sands using both the finite element method and the conventional elastic approach. The interaction among structures, its foundations and the soil medium below the foundations alter the actual behavior of the structure considerably than what is obtained from the consideration of the structure alone. Thus, a reasonably accurate model for the soil-foundation-structure interaction system with computational validity, efficiency and accuracy is needed in improved design of important structures. The study makes an attempt to gather the possible alternative models available in the literature for this purpose. In this study, a Conventional Elastic Method (CEM) is used in an attempt to obtain more accurate settlement prediction for non-linear behavoiur of the soil. The predicted settlements found by utilizing CEM are compared with a Finite Element Method (PLAXIS). The results indicate that CEM is a useful technique for predicting the settlement of shallow foundations on cohesionless soils, as they outperform the traditional methods for nonlinear behavoiur of the soil. A numerical model is purposed to analyze the elastic behaviour of the foundation in cohessionless soils foundation is assumed to be constructed in a homogeneous and nonlinear medium. The purposed model is implemented in an axi-symmetry finite element code. The effect of the diameter of the footing on the settlement behaviour of the foundation-soil system also focused Finite Element Method based software namely PLAXIS has been used for the present study. vi Plaxis is a finite element package that has been developed specifically for the analysis of deformation and stability in Geotechnical Engineering Projects. The simple graphical input procedures enable a quick generation of complex finite element models, and the enhanced output facilities provide a detailed presentation of computational results. The study shows that stresses and settlement vary considerably with varying the elastic modulus of soil under the foundation, as well as with changing the footing size