Editors’ Note

Abstract

Issue 2 of 2016 presents our readers with an interesting committee project pioneered by James Johnson of Condon-Johnson and Associates along with selected team members and collaborators of the DFI Drilled Shaft Committee. Within four manuscripts the issue describes a comprehensive comparison study between drilled shaft/bored pile practice in Europe and North America (i.e., US and Canada) focusing on the design, construction, contracting, quality control and implementation of recent technologies into the deep foundation industry. The material was presented at conference sessions of the 2014 DFI Annual Conference on Deep Foundations in Atlanta, Georgia, and the 2015 International Foundations Congress and Equipment Expo (IFCEE) in San Antonio, Texas. These sessions were organized and moderated by Alan Macnab, P.Eng., D.GE, a practicing engineer with 40 plus years of experience in the drilled shaft/earth retention contracting industry. The presentations received enthusiastic audience feedback which stimulated further discussion on how the deep foundation practice between the two continents can be better aligned and knowledge be better exchanged. The presentations, lessons learned and discussions that followed are documented in this Issue and provide the reader with an interesting assessment study of our industry. For the purpose of this study the project team members (i.e. authors of the subsequent papers) were paired by geographic location, i.e., US team members collaborated with European team members to provide a detailed synopsis of the respective study topic. Conclusions drawn from the study were supported by data from a comprehensive project survey conducted on both continents. Brown, Wulleman and Bottiau present a comparison of design practice and recognize that while common trends in the design of deep foundations exist, local practice dictates much of the implementation. In addition thereto, differences in construction techniques (e. g., drilling fluids, reinforcement details, base cleaning) have an impact on the early design stages before construction starts. Marinucci and Jue follow up by investigating differences in construction methodology and note that in Europe, bored pile practice typically follows performance-based methodology and specifications, whereas, in North America, traditional prescriptive-based methodology and specifications are more widely used. In addition differences with respect to casing, usage of drilling fluid and safety requirements dictate the deep foundation construction. Coleman and Tipter explore the contracting methods, document forms, payment methods, contracting provisions, and regional influences in North America and Europe. Given the multitude of contract forms and the involvement of specialty contractors (and the legal responsibilities thereof) the concept of a “team approach” emerged among all comparisons, which would allow for more innovations, reduction of risk and a better methodology of risk sharing among all parties. Hertlein, Verbeek, Fassett and Arnold explore the current state of construction technologies and how some of those techniques are implemented in the quality management (QM) and quality assurance (QA) of drilled shafts. Recent technological developments including their integration in Europe and North America are discussed. In addition a review of QA approaches on both continents is provided along with code standards and guidance documents for each. Selected methodologies within the nondestructive and destructive range are explored and described in further detail. We hope that this case study can provide an interesting and contemporary mirror of the current state of drilled shaft / bored pile construction on the North American and European continent and spark an intellectual exchange and awareness for collaboration to advance our deep foundation industry together.