Calibrated Analytical Formulas for Foundation Model Parameters

Abstract

A set of analytical formulas for the estimation of foundation model parameters is presented by synthesizing mechanical models at three different levels with corresponding variants of a generalized continuum model presented recently. The generalized continuum model was derived using a unified approach on the basis of a subgrade idealized as an elastic layer of finite thickness overlying a rigid base without making prior simplifying assumptions. The spring stiffness in all variants is inversely proportional to the layer thickness, rendering the model sensitive to this parameter with the potential to yield excessively large deflections for thick formations. This problem is alleviated by eliminating the layer thickness through introduction of a calibration factor in the form of a ratio of the layer thickness to the foundation width. It has been demonstrated that the calibration factor for each model type can be established from comparative analytical-numerical studies. Values obtained in this manner are suggested for practical use. The proposed calibrated formulas have potential applications in routine analysis of beam-like and plate-like shallow foundations and rigid pavements.