In 1994, the U.S. Department of Transportation/Federal Highway Administration (FHWA) initiated a state-of-practice review into the use of small diameter drilled micropiles. At that time, the use of such structural elements was regarded as innovative and, perhaps, "unproven" in many sections of the U.S. engineering community. The emphasis of this review was targeted at drilled micropiles, i.e., those micropiles that were installed using geotechnical drilling techniques and rigs similar to those used for ground anchoring, soil nailing, grouting and related processes. The study was conducted by Principal Investigators Dr. Donald Bruce of Nicholson Construction Company (at that time) and Prof. Ilan Juran of the Polytechnic University, Brooklyn, New York.
As part of this research program, the investigators commissioned an international peer review group to advise the state-of-practice research team. This peer review group consisted of Dr. Fernando Lizzi (Italy); Dr. Thomas Herbst (Germany); Drs. Francois Schlosser and Roger Frank (France), who at that time were engaged on the "Clouterre" and "FOREVER" research projects into the behavior and design of soil nails and micropiles, respectively; Mike Turner (U.K.); and Drs. Fred Kulhawy and James Mason (U.S.).
The four-volume FHWA State of Practice document (FHWA Publication Nos. FHWA-RD-96-016 to FHWA-RD-96-019 "Drilled and Grouted Micropiles: States of Practice Review") was published in 1997, and is perceived to have had a major influence on the development and growth of micropiling in the U.S. and Canada. The micropiling market was recorded as doubling in size in the 5 years after the publication of the report. Many elements of the FHWA State of Practice have also found their way into the BSEN14199 micropiling standard.
The International Workshop on Micropiles (IWM)
The synergy of the core group of state-of-practice researchers and peer group advisors evolved into the International Workshop on Micropiles (IWM). The wish to carry on the cooperative alliance formed by the group was fuelled by a growing awareness in other parts of the world of the potential advantages and use of micropiles, with their resilience, high load-carrying capacity and ability to be installed through difficult or obstructed ground. Appreciation of the potential advantages of micropile systems grew particularly in the Far East; most importantly in Japan, where the possibilities for retrofitting earthquake-sensitive structures drew great interest. These contacts led to the formation of the Japanese Association of Micropiles (JAMP) in 2001, to develop the design, practice and use of high-capacity micropiling systems in Japan.
In addition, in Scandinavia, for example, deep driven, jacked or drilled micropiling systems were being developed to address the need for repairs to existing structures or new-build works in urban areas underlain by deep deposits of sensitive clays overlying bedrock.
The IWM facilitated the interchange of ideas and experience of micropile systems and provided a forum for the exchange of knowledge, experience and advice to those either involved or interested in developing the techniques for other areas, conditions and applications.
IWM grew to 80 active members and positioned itself as a center of knowledge on techniques and use of high-capacity micropiles. To foster permanence of this group and highlight its increasing role as a repository of micropiling resources, IWM incorporated formally into a stand-alone society as the International Society of Micropiles (ISM).
In 2006, the ISM was incorporated in the Commonwealth of Pennsylvania. Countries sponsoring members and providing major contributions to the IWM/ISM throughout the years include the U.S., France, Japan, Germany, Finland (and other Scandinavian countries), Italy, Belgium, Canada, and the U.K. A Steering Committee comprising one member from each of the original contributing countries (U.S., Canada, Japan, U.K., Finland, France and Germany) guides the activities of the group.