FEATURE ARTICLE Yanzhou Verteiler 3: Crew arranges heat exchanger tubing at Yanzhou hospital site in China (Photo: Enercret) Energy foundations continue to gain popularity worldwide. Industry experts and academics from four continents are working together to advance this environmentally-friendly technology. Professor Heinz Brandl, Vienna University of Technology, who pioneered the technology some 30 years ago, said Austria, Germany and Switzerland have completed the most energy foundation projects he knows of. England has added more in recent years, according to Brandl, and China and [South] Korea also are adopting the technology, mostly with Austrian know-how. Australia is starting the technology as well. Brandl lists additional countries with energy foundation projects: Belgium, Canada, Dubai, Finland, France, Italy, Japan, Liechtenstein, Netherlands, Slovakia, Spain and the United States. Europe Recent activity in the United Kingdom and mainland Europe indicates significant steps toward refining the design of energy foundation piles. AUTHOR International Cooperation Expands Energy Foundation Technology Research. “Thermo-mechanical behaviour of energy piles,” published June 2012 in Geotechnique, summarizes the results of three published field studies. The article was co-authored by Binod L. Amatya, Halcrow Group Limited, London; Kenichi Soga, University of Cambridge; Peter J. Bourne-Webb, Instituto Superior Techico, Lisbon; Tony Amis, Geothermal International (GI), Coventry, England; and Lyesse Laloui, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland. Energy foundation piles were studied in buildings at Lambeth College in England, EPFL in Switzerland and Bad Schallerbach in Austria. The field studies examined pile-soil interactions that occur as energy foun- dation piles expand and contract during heating and cooling cycles. The authors attributed differences in pile response to thermo-mechanical load among the three trials, mostly, to ground conditions, end restraint and thermal load. They concluded that the heating and cooling of energy piles are unlikely to have detrimental effects on buildings, provided that: Sharon Boranyak, Independent Technical Writer, Topeka, Kansas DEEP FOUNDATIONS • MAR/APR 2013 • 51 • Design concrete stresses are not exceeded. • Conventional factors of safety for skin friction and end bearing are maintained. • Foundation settlements are limited. “Energy Pile Performance and Preventing Ground Freezing,” presented at the 2012 International Conference on Geomechanics and Engineering in Seoul, South Korea, addresses concerns that excessive temperature changes in the ground affect pile capacity. Such concerns may result in overly conservative energy foundation designs, specifically tem- perature limits for the thermal fluid circulating in the piles. Authors Fleur Loveridge and William Powrie of the University of Southampton, U.K., and Tony Amis of GI, used typical heating and cooling demand profiles applied to numerical models of pile heat exchangers to examine the likely temperature dif- ferences between the thermal fluid and the ground during heat pulses of different magnitudes and durations.
