Settlement of shallow foundation on cohesionless soil considering modulus degradation of soil
Date of Issue2011
School of Civil and Environmental Engineering
Settlement of shallow foundation on cohesionless soil is an old topic and a number of methods have been proposed in the literature. However, accurate settlement estimation of shallow foundation on cohesionless soil is still a challenge. The main difficulty is that modulus of in situ cohesionless soil depends not only on soil properties such as relative density, but also foundation properties, such as foundation size and load on the foundation. Therefore, a rational way for estimating the foundation settlement should consider the modulus degradation of soil from small-strain stiffness G0. The main objective of this research is to propose a practical method for better estimation of settlement of shallow foundation of all sizes on cohesionless soil by considering the modulus degradation from small-strain stiffness. Majority of the proposed methods for estimating settlement of shallow foundation on cohesionless soil rely on elastic solution of vertical displacement influence factor or vertical strain influence factor diagram. The effects of Poission’s ratio, foundation rigidity, foundation shape and finite soil thickness on the vertical strain influence factor diagram were investigated numerically in this research. A simplified vertical strain influence factor diagram and correction factors were proposed to account for foundation rigidity, foundation shape and finite soil thickness. Many proposed methods also adopted ultimate bearing capacity of the shallow foundation to normalize foundation load to improve settlement estimation. Therefore, a commonly recognized phenomenon of the ultimate bearing capacity of shallow foundation, i.e., the so-called “scale effect” of bearing capacity was investigated using numerical method.