Abstract

The mechanisms behind the installation of a driven pile in sands are complex and difficult to identify from field tests. Phenomenon such as grain breakage, local variations in sand density, pile abrasion and arching effects, are commonly studied through indirect methods or by using small laboratory models. This article presents the results of an experimental laboratory research devoted to the analysis of the soil kinematics during the installation of an uninstrumented close-ended model pile in a specimen of siliceous sand. The research has focused on understanding the micromechanical aspects of the installation process by focusing on sand-pile interaction around the pile's tip. A three dimensional displacement field was obtained with the combined use of x-ray tomography and three dimensional digital image correlations. The results show two well-identified zones where the displacement and therefore strains concentrate. The interaction of these zones, which are linked by consecutive phases of sand contraction and extension as the pile embeds into the sand, gives new ideas about the mechanisms controlling the pile shaft friction.