Scaling Rule for Stiffness of Foundations

Abstract

The stiffness of shallow foundations on homogeneous soil layers can be predicted by means of an in‐situ model test and a scaling rule. In this paper, the existing scaling rules are reviewed first. Then a scaling rule is developed on the basis of a constitutive model for frictional materials. The material behavior is categorized by two characteristic stiffnesses: deviatoric loading and isotropic compression. The parameter in the scaling rule can be determined on the basis of either a series of drained triaxial tests or a series of in‐situ‐plate‐loading tests. Both approaches are verified experimentally. The practical relevance of the scaling rule is illustrated by an example. For a scale factor of 10, the dependence of both characteristic stiffnesses on the magnitude of the isotropic stress can cause errors in the predicted settlement of a factor of two. For an accurate determination of the foundation stiffness at small load levels, a large‐diameter model plate is required, and special attention must be given to the contact between the plate and the soil.