Abstract
The behavior of geothermal energy piles in a group involves complex relation between change in temperature and deformations, strains and stresses in the pile and soil. The behavior of piles when acting as a group is further complex due to group interaction among the piles. Hence, it becomes important to quantify the displacements and stresses to understand the load transfer mechanism of these piles under thermal and mechanical loads. In the present study, rigorous numerical analyses are performed to investigate the thermo-mechanical behavior of the piles in sand using three dimensional nonlinear finite element analysis procedure in Abaqus software. The stress-strain behavior of piles is considered as linear-elastic. The stress-strain response of sand is reproduced using constitutive model CASM. The raft on the piles is modeled to behave in a linear elastic manner. The state parameter based constitutive model CASM is implemented in finite element based software Abaqus through two user defined material subroutines, UMAT and UMATHT. The energy piles in a group are analyzed by considering different combinations of thermal and mechanical piles in a single layer of Ottawa sand. The results of numerical analyses have been presented for the pile base displacement. Parametric sensitivity analyses are carried out to investigate the influence of pile spacing and soil relative density on the base displacement of the piles. The results conclude that the thermal piles experience higher displacement as compared to the mechanical piles and soil relative density plays a key role in governing the pile response to thermal cycle. Differential settlement is noted for the pile groups containing the thermal and mechanical piles altogether.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Abaqus/Standard User’s Manual, Version 6.11.: Dassault Systèmes Simulia Corporation, Providence (2011)
Bourne-Webb, P.J., Amatya, B., Soga, K., Amis, T., Davidson, C., Payne, P.: Energy pile test at Lambeth College, London: geotechnical and thermodynamic aspects of pile response to heat cycles. Géotechnique 59(3), 237–248 (2009). https://doi.org/10.1680/geot.2009.59.3.237
Brandl, H.: Energy foundations and other thermo-active ground structures. Géotechnique 56(2), 81–122 (2006)
Carraro, J.A.H.: Mechanical behavior of silty and clayey sands. Ph.D. Dissertation, Purdue University (2006)
Dupray, F., Laloui, L., Kazangba, A.: Numerical analysis of seasonal heat storage in an energy pile foundation. Comput. Geotech. 55, 67–77 (2014)
Green, A.E., Naghdi, P.M.: On undamped heat waves in an elastic solid. J. Therm. Stress. 15, 253–264 (1992)
GSHP Association: Thermal Pile Design, Installation and Materials Standards. Ground Source Heat Pump Association, National Energy Centre, Davy Avenue, Knowlhill, Milton Keynes, MK5 8NG (2012)
Jeong, S., Lim, H., Lee, K.J., Kim, J.: Thermally induced mechanical response of energy piles in axially loaded pile groups. Appl. Ther. Energy 71, 608–615 (2014)
Laloui, L., Nuth, M., Vulliet, L.: Experimental and numerical investigations of the behavior of a heat exchanger pile. Int. J. Numer. Anal. Methods Geomech. 30, 763–781 (2006)
Loria, A.F.R., Laloui, L.: Thermally induced group effects among energy piles. Géotechnique 67(5), 374–393 (2017)
Murthy, T.G., Loukidis, D., Carraro, J.A.H., Prezzi, M., Salgado, R.: Undrained monotonic response of clean and silty sands. Géotechnique 57(3), 273–288 (2006)
Loukidis, D.: Advanced constitutive modeling of sands and applications to foundation engineering. Ph.D. thesis, Purdue University (2006)
Poulos, H.G.: Piled raft foundations: design and applications. Géotechnique 51(2), 95–113 (2001)
Saggu, R., Chakraborty, T.: Thermal analysis of energy piles in sand. Geomech. Geoeng. Int. J. 10(1), 10–29 (2015a). https://doi.org/10.1080/17486025.2014.923586
Saggu, R., Chakraborty, T.: Cyclic thermo-mechanical analysis of energy piles in sand. Geotech. Geol. Eng. 33(2), 321–342 (2015b). https://doi.org/10.1007/s10706-014-9798-8
Saggu, R., Chakraborty, T.: Thermo-mechanical response of geothermal energy pile group in sand. Int. J. Geomech. (2016). https://doi.org/10.1061/(ASCE)GM.1943-5622.0000567
Saggu, R., Chakraborty, T.: Thermo-mechanical response of geothermal energy piles in sand and parametric study. Int. J. Geomech. (2017). https://doi.org/10.1061/(ASCE)GM.1943-5622.0000962
Salciarini, D., Ronchi, F., Cattoni, E., Tamagnini, C.: Some remarks on the thermomechanical effects induced by energy piles operation in a small piled raft. Int. J. Geomech. (2013). https://doi.org/10.1061/(ASCE)GM.1943-5622.0000375
Salgado, R.: Engineering of Foundations. McGraw-Hill, New York (2008)
Sasitharan, S., Robertson, P.K., Sego, D.C., Morgenstern, N.R.: State-boundary surface for very loose sand and its practical implications. Can. Geotech. J. 31(3), 321–334 (1994). https://doi.org/10.1139/t94-040
Tarnawski, V.R., Momose, T., Leong, W.H., Bovesecchi, G., Coppa, P.: Thermal conductivity of standard sands. Part I. Dry state conditions. Int. J. Thermophys. 30(3), 949–968 (2009)
Wang, B., Bouazza, A., Haberfield, C.: Preliminary observations from laboratory scale model geothermal pile subjected to thermo-mechanical loading. In: Geo-Frontiers, ASCE 2011, pp. 430–439 (2011)
Yu, H.S.: CASM: A unified state parameter model for clay and sand. Int. J. Numer. Anal. Meth. Geomech. 22, 621–653 (1998)
Yu, H.S.: Plasticity and Geotechnics. Springer, New York (2006)
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2019 Springer Nature Switzerland AG
About this paper
Cite this paper
Saggu, R. (2019). Base Displacement Response of Group of Geothermal Energy Piles. In: Ferrari, A., Laloui, L. (eds) Energy Geotechnics. SEG 2018. Springer Series in Geomechanics and Geoengineering. Springer, Cham. https://doi.org/10.1007/978-3-319-99670-7_25
Download citation
DOI: https://doi.org/10.1007/978-3-319-99670-7_25
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-99669-1
Online ISBN: 978-3-319-99670-7
eBook Packages: EngineeringEngineering (R0)