LOAD-DISPLACEMENT BEHAVIOR OF SINGLE PILE IN SAND USING PHYSICAL MODEL TEST AND FINITE ELEMENT METHOD

Abstract

Load-displacement behavior of a pile is one of the key parameters in the foundation design of a high-rise building. This research studied the relationship between the load and displacement of a pile in sand using a physical model test and the finite element method (FEM). Five types of sandy soil, including Bangkok sandy soil, were tested using the physical model test with a pile 1 cm in diameter and 30 cm in penetrated length. The results showed that the relationship between the load and actual pile displacements in all soil types was nonlinear with an elastoplastic-strain hardening pattern. This relationship was expressed using a polynomial function for a displacement in the range 0–20 percent of the pile diameter. For easy use, the relationship can be considered a linear function only in the first stage of displacement (0–10 percent of pile diameter), confirming that linear pile spring stiffness can be reasonably used for the design of the foundation. In addition, the finite element method was used to investigate the effect of various factors on pile spring stiffness. The results showed that pile spring stiffness depended on diameter, length, and modulus of the pile and on the soil modulus. In natural soil, the modulus of soil was related to the soil strength and the pile spring stiffness also depended on the soil strength.