A simple method to predict elastic settlements in foundations resting on two soils of differing deformability

Abstract

This paper shows the analysis results obtained from more than 200 finite element method (FEM) models used to calculate the settlement of a foundation resting on two soils of differing deformability. The analysis considers such different parameters as the foundation geometry, the percentage of each soil in contact with the foundation base and the ratio of the soils’ elastic moduli. From the described analysis, it is concluded that the maximum settlement of the foundation, calculated by assuming that the foundation is completely resting on the most deformable soil, can be correlated with the settlement calculated by FEM models through a correction coefficient named “settlement reduction factor” (α). As a consequence, a novel expression is proposed for calculating the real settlement of a foundation resting on two soils of different deformability with maximum errors lower than 1.57%, as demonstrated by the statistical analysis carried out. A guide for the application of the proposed simple method is also explained in the paper. Finally, the proposed methodology has been validated using settlement data from an instrumented foundation, indicating that this is a simple, reliable and quick method which allows the computation of the maximum elastic settlement of a raft foundation, evaluates its suitability and optimises its selection process.

Keywords:

• foundations
• soil/structure interaction
• settlement
• elasticity
• finite element modelling

Acknowledgements

This study was undertaken as part of the UNED “Máster en Teoría y Aplicación Práctica del Método de los Elementos Finitos y Simulación” and was funded by the Generalitat Valenciana (GV/2011/044) and the University of Alicante (VIGROB-157). The authors wish to express their gratitude to Iker Oliva Climent (Eptisa Engineering Monitoring and Control) for their assistance with the settlement field data. Finally, authors are extremely grateful to the Prof. Pierre Philippe from the National Research Institute of Science and Technology for Environment and Agriculture (IRSTEA, France), for the essential help provided in fitting the experimental data.

Disclosure statement

No potential conflict of interest was reported by the authors.