Evaluation of thermo-mechanical and thermal behavior of full-scale energy foundations

Murphy, Kyle D.; McCartney, John S.; Henry, Karen S.

doi:10.1007/s11440-013-0298-4

Cited by 204 publications

(73 citation statements)

References 20 publications

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“…The order of magnitude of the observed vertical stress variation was comparable to other experimental data from the literature (e.g. Murphy et al, 2015) that involved significant energy exploitations through the use of energy piles. Lower positive vertical stress changes were observed in the bottom portion of EP1.…”

Section: Vertical Stress Variations Along the Energy Pilessupporting

confidence: 86%

“…The suitability of linear thermo-elasticity for the analysis of end-bearing energy piles such as the group that was analysed in this study is extended to other testing conditions and sites based on the experimental observations of Murphy et al (2015), Mimouni & Laloui (2015) and Wang et al (2014) as well as the numerical results of Di Donna et al 2016). Linear thermo-elasticity appears to be suitable also for the analysis of groups of friction energy piles.…”

Section: Suitability and Limitations Of Using Thermo-elasticity For Smentioning

confidence: 97%

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Thermally induced group effects among energy piles

Loria

2017

Géotechnique

143

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The behaviour of conventional pile groups (e.g. closely spaced) that are subjected to mechanical loads has been shown to be different from the behaviour of single isolated piles. The so-called 'group effects' are responsible for this behaviour and must be considered for an optimal design of pile foundations. In recent years, energy piles have shown potential to work as both structural supports and geothermal heat exchangers, and thus are subjected to both mechanical and thermal loads. An increasing amount of research has investigated the previously unexplored impact of thermal loads on the thermo-mechanical behaviour of energy piles. However, no field data over typical timescales of practical geothermal applications have been available to analyse the development and impact of thermally induced group effects between energy piles (e.g. closely spaced) on their thermo-mechanical behaviour. To investigate this problem, a full-scale in situ test of a group of energy piles and coupled three-dimensional thermomechanical finite-element analyses were performed and are presented in this paper. This work demonstrates that significant thermally induced group effects characterise closely spaced energy piles. Attention must be devoted to these effects throughout the design process (e.g. geotechnical, structural and energy) of energy piles because they play an important role in the serviceability performance of these foundations.

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Section: Vertical Stress Variations Along the Energy Pilessupporting

confidence: 86%

Section: Suitability and Limitations Of Using Thermo-elasticity For Smentioning

confidence: 97%

Thermally induced group effects among energy piles

Loria

2017

Géotechnique

143

View full text Add to dashboard Cite

show abstract

“…The fullscale field experiments reported by Brandl (2006), Laloui et al (2006), Bourne-Webb et al (2009), Akrouch et al (2014), Mimouni and Laloui (2015), Murphy et al (2014) and Wang et al (2015), as well as experimental set-ups by McCartney and Rosenberg (2011), Kalantidou et al (2012), Stewart and McCartney (2013), Ng et al (2014) and Yavari et al (2014a) have provided an invaluable insight into the behaviour of thermo-active piles. Moreover, the results of the first field tests (Bourne-Webb et al, 2009;Brandl, 2006;Laloui et al, 2006) have led to the development of a simplified descriptive framework for thermo-mechanical pile response (Amatya et al, 2012;Bourne-Webb et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of thermo-active piles in London Clay

Gawecka

Taborda

Potts

et al. 2017

Proceedings of the Institution of Civil Engineers - Geotechnica

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Thermo-active foundations utilise heat energy stored in the ground to provide a reliable and effective means of space heating and cooling. Previous studies have shown that the effects of temperature changes on their response are highly dependent on their interaction with the surrounding ground. Consequently, it is necessary to consider this interaction and include both the thermal and mechanical behaviour of the ground in design. This paper addresses this issue by performing state-of-the-art finite-element analyses using the Imperial College Finite Element Program, which is capable of simulating the fully coupled thermo-hydro-mechanical behaviour of porous materials. First, the Lambeth College pile test is analysed to demonstrate the capability of the adopted modelling approach to capture the observed response under thermo-mechanical loading. Subsequently, a detailed study is carried out, demonstrating the impact of capturing the fully coupled thermo-hydro-mechanical response of the ground, the use of appropriate boundary conditions and the uncertainty surrounding thermal ground properties. It is demonstrated that the modelling approach has a large impact on the computed results, and therefore potentially on the design of thermo-active piles. Conversely, the effects of thermal conductivity and permeability of the soil are shown not to influence the pile behaviour significantly.

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“…The mobilised side shear stress f s,mob,j at different heights in the soil layer can be determined as follows (Murphy et al, 2015) f s;mob;j ¼ ðs…”

Section: Environmental Geotechnics Volume 3 Issue Eg4mentioning

confidence: 99%

Model tests of energy piles with and without a vertical load

Wang

Liu

Kong

et al. 2016

Environmental Geotechnics

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The thermomechanical behaviour of energy piles during heating and cooling through model tests was studied. These model tests were carried out both with and without a vertical load and dry sand was used. The axial load distribution, load-settlement of the pile head, pile and soil temperature, soil pressure at the pile tip, horizontal soil pressure, thermal stress and mobilised side shear stress were investigated. The magnitude of stress and displacement influenced by vertical load or no load was comparatively analysed. The results show that heating and cooling induced thermal stress in piles and residual thermal stress was introduced after a heating and cooling cycle.Horizontal soil pressure also varied and changes in soil pressure at the pile tip differed depending on whether or not a vertical load was applied. Moreover, the pile temperature and the temperature within one pile diameter of the pile axis varied noticeably in the condition of this paper. The heave under no load was 143% of that under a vertical load after heating, while the settlement under no load was only 64% of that under vertical load after cooling.

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Evaluation of thermo-mechanical and thermal behavior of full-scale energy foundations

Cited by 204 publications

References 20 publications

Thermally induced group effects among energy piles

Thermally induced group effects among energy piles

Numerical modelling of thermo-active piles in London Clay

Model tests of energy piles with and without a vertical load

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