Settlement Behaviour of Non-Linear Soil around Single Piles Subjected to Vertical Loads

Abstract

ABSTRACT A simplified non-linear analysis is performed to investigate the distribution of vertical displacement in the soil around a friction or floating pile vertically loaded, where contributions of pile base to pile stiffness and to load capacity are negligibly small. A model describing the non-linearity of shear modulus and shear strain is propped based on published laboratory tests data. The non-linear settlement behaviour is also examined by using a hyperbolic relationship between shear stress and shear strain. The results are compared with the linear elastic solutions obtained by boundary element analyses and the observation in published pile load tests. The non-linear analyses result in more concentration of shear strain near the pile shaft surface even under working loads than those of the linear elastic analyses, where the vertical displacements in the soil decrease linearly with the logarithm of a distance in a radial direction from the pile axis at the level of mid-pile depth. For practical application of theoretical elastic solutions, an appropriate equivalent shear modulus is recommended as three times the shear modulus obtained by conventional triaxial tests. It is confirmed that using the equivalent modulus a theoretical solution predicts a good correspondence with in situ measurements of vertically loaded pile.