DFI / ADSC Joint Micropile Committee Meeting – October 19, 2011

The next DFI / ADSC Joint Micropile Committee meeting will take place at the DFI 36th Annual Conference on Deep Foundations in Boston, MA on Wednesday, October 19th from 10AM to 12PM. All committee members are encouraged to attend. The venue location is below:

The Seaport Hotel and World Trade Center
One Seaport Lane
Boston, MA 02210
1-877-SEAPORT

To see a copy of the latest Chairman’s report for the Joint Committee, click HERE.

More information on the 36th Annual Conference on Deep Foundations can be found HERE. See you in Boston!

Jon Bennett Joins Brayman Construction Corporation

BRAYMAN CONSTRUCTION IS PLEASED TO ANNOUNCE THE ADDITION OF JONATHAN BENNETT TO THEIR MID-ATLANTIC REGIONAL LOCATION

Saxonburg, PA (June 8, 2011) — Jonathan Bennett, PE, D.GE, M.ASCE has recently joined the Brayman Construction Corporation team as Chief Engineer; Mid-Atlantic Region. Operating out of Brayman’s Manassas, VA office, Bennett will head the efforts to develop the Mid-Atlantic market for Brayman’s Foundation Division for specialties such as caissons, marine and piling and drilling and grouting. Jon can be contacted at (304) 707-4840.

Brayman Construction Corporation is a leading regional, specialty and general contractor guided by values of EQUITY, URGENCY, TENACITY and PROFESSIONALISM. Incorporated in 1947, grown and diversified by the current ownership/leadership since 1992, Brayman has become a nationally recognized provider of heavy civil construction projects. Brayman’s competencies include: large scale, complex bridges, broad based geotechnical construction, marine and dam construction and rehabilitation, complex and heavy steel erection and rehabilitation and demolition services. The company targets technically challenging projects in all of the above areas of expertise.

Visit our website at: www.brayman.com for additional information.

A Brief History of Micropiles

The first use of micropiles dates back to the early 1950’s in Italy, where new methods of underpinning for existing structures were needed to restore structures and monuments damaged during World War II (Lizzi, 1982). Dr. Fernando Lizzi is commonly recognized as the inventor of micropiles in the form of the root pile or palo-radice.

Dr. Lizzi was a civil engineer and Technical Director with the Italian specialty foundation contractor Fondedile and obtained the first patents for root piles in Italy in 1952. This early form of micropile technology was used extensively in Europe for the restoration of various structures and monuments.

Fondedile introduced micropiles into North America in 1973 by performing a number of projects, mainly in the Northeastern United States. By the mid 1970’s a number of US specialty foundation contractors previously engaged in drilled and grouted anchor work had developed their own variants of the technology. There was slow growth of the technology in the time period between the mid 1970’s and the mid 1980’s with Fondedile closing their North American venture for economic reasons. (Bruce and Juran, 1997)

There has been a rapid growth in the specification and use of micropiles in the United States since the mid 1980’s to early 1990’s partly as a result of FHWA research efforts, trade association promotion efforts and the development of various publications offering standardized design and specification guidelines.

In the early 1990’s, the Intermodal Surface Transportation Efficiency Act (ISTEA) provided massive funding for the rehabilitation of highway infrastructure in the United States. As part of this effort, the FHWA undertook a number of research and development projects associated with specialty geotechnical construction to encourage innovation in geotechnical applications and produced several design manuals including the first on micropiles. This was the beginning of the surge in micropile use in the United States.

In 2006 and 2007 respectively, the International Building Code and the AASHTO LRFD Bridge Design Specifications incorporated design code sections for micropiles thus making way for further expansion of applications in both building and highway construction. Micropiles currently are widely specified and used in all construction sectors worldwide.

Dr. Fernando Lizzi

Performance Features of Micropiles

Micropiles can be installed at various angles from vertical and are capable of resisting both axial and lateral loads. The unique structural makeup of micropiles has an effect on the way in which they develop their load resistance and how they behave in response to these loads at various inclinations.

Micropiles develop their axial capacity primarily through the bond between grout and soil or rock in the bonded zone of the pile. Because of this, micropiles provide both tension and compression resistance thus making them useful in a variety of applications, particularly where resistance to uplift is needed in addition to resisting compression or gravity loads.

With the majority of micropile axial load being resisted by steel casing or internal reinforcing core, micropiles exhibit relatively high axial stiffness and are capable of resisting large axial loads. Micropiles that are fully bonded exhibit even higher apparent stiffness than those that are partially unbonded for the same steel area.

Because of the installation methods (down-hole hammer and rotary-percussive drilling) and equipment used, micropiles can be installed in soil and rock conditions where the use of other conventional deep foundation systems are not a reasonable alternative, such as in Karst topography or where modest subsurface obstructions or boulders are present. Micropiles can be installed through modest obstructions and boulders that would be problematic for installation of helical piles, driven piles, drilled shafts or augercast piles. They can also be drilled into pinnacled rock where achieving acceptable anchorage or bearing for other deep foundation types might be questionable.

Micropiles can be easily installed in caving soils and below the water table by either using casing or hollow bar micropile installation methods. Caving soils and elevated water can be problematic for deep foundation systems that rely on open hole drilling such as drilled shafts.

Compact and low headroom drilling equipment is available such as to make installation of micropiles possible in low-headroom or limited space applications where the installation of other types of conventional deep foundation systems is not possible. Examples of this are applications where supplemental foundation support is required in basements or areas with overhead restrictions or otherwise small or space restricted areas where relatively large equipment cannot fit.

The drilling and installation equipment used for micropiles does not produce an amount of vibration that would be harmful to structures as opposed to driven piles which can produce magnitudes of vibration that have the potential for causing settlement of adjacent structures resulting in structural damage. For this reason micropiles are well suited for use in close proximity to existing structures.

Micropiles are ideal for retrofit applications in that they can easily be installed through a core drilled hole in an existing foundation or footing and anchored to the existing foundation for load transfer.

Introducing Micropile.org

Effective immediately, the domain http://www.micropile.org will point to this site. The blog will continue to be accessible via the https://micropileman.wordpress.com as well for the next few months. During that time, we will be making preparations for migrating the content fully to the micropile.org domain. Please check the site often for new developments in the micropile industry and for useful information on micropiles in general. We will give plenty of notice prior to actually moving the site. The mission of micropile.org is the be THE online source for information and resources relative to micropile design and construction.

Deep Foundations Institute LinkedIn Group

The Deep Foundations Institute has formed a Group on LinkedIn. If you are a Deep Foundations Institute Member and have a LinkedIn profile, search for the Deep Foundations Institute Group on LinkedIn and request to become a member of the Group. We have also formed a Subgroup for the DFI Micropile Committee and plan to set up Subgroups for all of the DFI Committees. If you are a member of the DFI Micropile Committee, you will be receiving an invitation to join the Subgroup soon. If you do not currently have a LinkedIn profile, I encourage you to create one so that you can take advantage of these new opportunites to stay up to date on DFI and Industry happenings. Visit LinkedIn at www.linkedin.com. The International Association of Foundation Drilling (ADSC) also has a LinkedIn Group.

Welcome!

Welcome to the Micropile Design and Construction Blog! This is your online source to up-to-date micropile design and construction news and information. This effort is currently a work in progress and probably always will be due to the constantly changing nature of the industry. It is my hope that this will be a valuable resource to those who are interested in micropiles or foundation engineering in general. Enjoy!