Performance of Bored Piles Constructed Using Polymer Fluids: Lessons from European Experience

Abstract

Solutions of synthetic water-soluble polymers have been used for the construction of bored piles (drilled shafts) since the early 1990s. These engineered fluids are very different from conventional bentonite slurries but there is currently a serious lack of industry guidance. Despite their advantages over bentonite, performance issues have arisen in the past and foundation engineers remain wary of their use. To help practicing engineers avoid past pitfalls and to promote best practice, this paper presents a critical reappraisal of selected European case histories of bored piles constructed using polymer fluids. A collective reassessment is necessary in order to provide an overall picture of the situation as individual cases may show conflicting results. It is found that the completed piles can have excellent load–movement characteristics if polymer behavior is understood and respected. Conversely, excavation instability, structural defects, and poor pile performance can result if the special properties of these fluids are not fully appreciated and as a result they are not properly maintained. The findings presented in this paper will be useful for consultants and contractors when designing and constructing piles and diaphragm walls utilizing polymer fluids in the future.