2014 PGS Workshop & 12th G.A. Leonards Lecture

April 26, 2014 - 4:30 p.m.
Purdue University, Krannert Auditorium, West Lafayette, IN

Advances in the Analysis of Thermo-Active Foundations

Dr. Lyesse Laloui

Chair Professor of Soil Mechanics, Geo-Engineering and CO2 Sequestration
Swiss Federal Institute of Technology (EPFL), Lausanne

Thermo-active foundations are foundations equipped with absorber pipes, for exchanging heat with the surrounding ground. They provide an energy-efficient solution for heating and cooling of buildings based on the concept of shallow geothermics. Ground source heat pumps are linked to the ground through ground heat exchangers and to the building through the heating network. This system is forming the so-called ground source heat pump system (GSHP), whose efficiency is directly linked to the efficiency of these three components. Temperature variations induced by this system in the foundations bring new geotechnical challenges. Indeed, thermal expansion or contraction of the foundations can lead to building movements and additional thermal induced stresses must be kept within acceptable limits. Therefore, a new design approach is adopted. This lecture provides insights into the advances carried out to tackle the various challenges linked to thermo-active foundations and their geotechnical design. Contributions of in situ experiments carried out on real-scale energy piles are reviewed. The outcome of these tests constitutes the basis for the development of a design tool, called Thermo-Pile. Furthermore, analysis of the soil-structure interface in non-isothermal cyclic conditions imposed by energy piles is presented. Examples of thermo-hydro-mechanical numerical analyses are presented to illustrate the challenges encountered when using thermo-active foundations. Other geotechnical applications are also illustrated. They deal with the sustainability of heat storage through tunnel anchors as well as for the de-icing of bridges. In this last case, seasonal storage of solar heat energy captured directly through the asphalt layer is presented as a promising solution that can be achieved cost-effectively if the foundations are used as heat-exchangers. Finally, the last part of the lecture deals with the investigation of the thermo-active foundations performance in the context of innovative applications (geothermal systems integrated with other renewable heat sources/collectors, i.e. where the ground stores heat for renewable energy systems) and extreme conditions (cold and warm climates).

Dr. Lyesse Laloui is a professor at the Swiss Federal Institute of Technology, EPFL, Lausanne, where he developed a large expertise in various areas of geotechnical engineering. His main research interests are in Geomechanics (Constitutive and numerical modelling of multiphysical coupling processes, laboratory advanced testing), and Environmental and Energy Sustainability (Nuclear waste underground storage, Petroleum Geomechanics, CO2 Geological Sequestration, Geothermal Energy). His state-of-the-art researches are mostly related to the mechanics of unsaturated soils and shales, the thermo-mechanics of clays as well as the development of the thermo-active foundations technology. He edited seven books and published more than 250 papers, was a guest editor for six journal special issues, and the Honorary Editor and Chairman of the Geotechnique Symposium in Print 2013 on Bio- and Chemo-mechanical Processes in Geotechnical Engineering. He is member of the editorial board for seven international journals, gave keynote and invited lectures to more than 25 leading international conferences and has been involved as an expert in several international projects. He is the recipient of the "Excellent Contributions Award" of the International Association for Computer Methods and Advances in Geomechanics and the "2012 Vardoulakis Lecture" from the University of Minneapolis. (Introduction by Philippe Bourdeau, Purdue University)

Presented in conjunction with the 12th Purdue Geotechnical Society Workshop - "Energy Geotechnics"

2014 Workshop Program

Row One: Michael Prentice, Anuj Choudhari, Chanjuan Han, Jianying Nu, Ayda Galvis, Cassandra Rutherford, Antonio Bobet, Leila Sadeghi, Urcula Merchak, Xiong (Bill) Yu, Sriram Valavala, Eimar Sandolval
Row Two: John Mundell, Kevin Ellett, Guney Olgun, Juan Santos, Samantha Willmann, Amy Getchell, Joe Sinfield, Marika Santagata
Row Three: Alain El Howayek, Tong Qiu, Mohammadhasan Sasar, Melis Sutman, Tolga Ozudogru, Daniel Muschett Henriquez, Vince Drnevich, Audai Theinat, Anahita Modiriasari, Jaewon Jang, Philippe Bourdeau
Row Four: Yazen Khasawneh, Fei Tao, Xianglei Zhang, Yuan Guo, Jiale Li, Wendell Solomon, Marcelo Sanchez, Cliff Johnston
Row Five: Sung Soo Park, Bate Bate, Ronaldo Luna, Quan Gao, Qiangbing Huang, Felipe Ochoa, John Gasper, John McLennan
Row Six: Ruben Tovar, Richard Woods, Reza Hedayat, Faraz Tehrani, Lyesse Laloui, Hao Cheng

Support for the PGS workshop and Leonards lecture is provided by the following sponsors: