Experimental And Numerical Study On Single Pile Subjected To Embankment Construction On Soft Clay

In recent decades, the rapid development of economy has been driving the need of infrastructures such as roads and dams, which are related to construction of embankment. In congested urban areas, it is inevitable to construct embankment adjacent to existing pile foundations and impose additional loadings on the piles, by inducing lateral soil movements around the piles. Piles subjected to lateral soil movements are usually referred as ’passive pile.’Previous research regarding’passive pile’is mainly focused on pile-soil interaction under undrained conditions. However, embankment constructions on soft clay are often accompanied by soil consolidation.The effects of clay consolidation on the responses (i.e., deformation and bending moment) of the pile foundation nearby are still not well understood. Meantime, the relevant design theory is still not complete enough, which is the starting point of this dissertation.In the first part of this study, full-scaled field tests and three-dimensional finite element analyses are carried out to investigate the effects of embankment construction on a single pile under undrained condition. Different embankment heights and locations of piles are considered.Since it is rather time consuming to simulate consolidation in the field (i.e., it would take years for primary consolidation), centrifuge model tests and three-dimensional finite element analyses (i.e., coupled-consolidation analyses) are carried out to study the effects of single pile subjected to lateral soil movement under various drainage conditions. Two typical embankment construction rates (corresponding to the undrained conditions and drained conditions) and two typical pile lengths (i.e., long pile, L=37.5D; short pile, L=18.75D) are considered. In addition, numerical parametric studies analysis are undertaken to study the influence of construction rates and pile lengths on pile responses.Base on this study, three major scientific contributions are made:1. It discloses the influences of embankment heights and locations of pile in relation to the embankment on lateral pile responses under the undrained conditions;2. It reveals two distinct deformation mechanisms of soils and adjacent piles (due to surcharge loading) under the drained and undrained conditions;3. It establishes the relationship between the pile responses and construction rates of embankment, as well as pile lengths. Design charts accounting for the two variables are also developed.