Cyclic Thermo-Mechanical Analysis of Energy Piles in Sand

Saggu, Rajni; Chakraborty, Tanusree

doi:10.1007/s10706-014-9798-8

Cited by 81 publications

(21 citation statements)

References 24 publications

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“…Saggu et al (2014) studied stresses and displacement of the energy piles in sand and the surrounding soil under cyclic thermo-mechanical loading using the software package Abaqus Simulia. They applied 50 cycles of thermal loading of ∆T = 21°C on different load magnitudes and concluded that Negative Shear stress is generated near the pile head in the soil and The ultimate capacity (limit load) of the energy pile is unaffected by temperature changes.…”

Section: Numerical Simulation and Analysismentioning

confidence: 99%

Assessment of Stress-Strain Behavior of Energy Piles Installed in Sand

Dubey¹

2017

Geomate

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ABSTRACT:The geothermal piles are dual functional geostructures which provide sub-structural support to the building and also fulfill the energy demands in terms of its climate control. For efficient design of geothermal piles, it is necessary to evaluate the thermo-mechanical behavior of geothermal piles. The purpose of this study is to evaluate the behavior of geothermal heat exchanger pile installed in sand, subjected to a coupled thermomechanical loading. Initially, in this study a full scale field test is simulated and results are compared. In the second phase, parametric study by varying mechanical and thermal loading on the geothermal pile placed in dense sand, is performed. In this study, the sand and geothermal pile are simulated as axis-symmetrical models, where pile is considered to be thermo-elastic in nature and sand is considered as Mohr-Coulomb elastic-plastic material. Coupled Temperature-Displacement analysis is applied in order to simulate the observed experimental results. It is shown that the simulated model is able to reproduce the major thermo-mechanical effects for the selected full scale model approximately. Stress and strain behavior along with the depth of energy pile induced by thermo-mechanical loading has been reported. It was concluded that when mechanical load value is comparatively low, the thermal variation influences the induced axial stress while at higher mechanical load the stress behaviour is nearly constant at different temperature variation.

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Section: Numerical Simulation and Analysismentioning

confidence: 99%

Assessment of Stress-Strain Behavior of Energy Piles Installed in Sand

Dubey¹

2017

Geomate

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“…The surrounding dense sand provides a relatively high resistance to thermal deformations of the pile and the soil at the current site. Numerical studies conducted by Saggu and Chakraborty (2015) showed that energy pile settlements in dense sand are much lower than in loose sand due to differences in the shaft friction. A comparative assessment of the Lambeth College and…”

mentioning

confidence: 99%

Axial and Radial Thermal Responses of a Field-Scale Energy Pile under Monotonic and Cyclic Temperature Changes

Faizal

Bouazza

Haberfield³

et al. 2018

J. Geotech. Geoenviron. Eng.

107

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The axial and radial thermal responses of a field-scale energy pile installed in dense sand and subjected to monotonic and cyclic temperatures are examined. It is found that the axial thermal strains in the pile are more restricted to thermal expansion/contraction compared to radial thermal strains. The radial thermal strains are close to that of a pile expanding/contracting freely, indicating minimal resistance from the surrounding soil in the radial direction. As a result, very low magnitudes of radial thermal stresses developed in the pile compared to axial thermal stresses. The pile-soil radial contact stresses estimated from cavity expansion analysis are up to 12 kPa for a pile temperature change of 22.5 o C and are likely negligible for the range of commonly-encountered operating temperatures of energy piles installed in dense sand. During cyclic heating and cooling, unstable changes in axial and radial thermal strains were observed initially during initial cycles indicating a ratcheting response. The changes in strains became more stable over further cycles, without significant changes in side friction, pile-soil contact stresses, or strength of the dense sand.

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“…Notable variations in the behaviour of friction energy piles may consequently arise because of the marked sensitivity of these foundations to the response of the pile-soil interface . These variations may increase for cyclic thermal loads applied to the piles with time (Di Donna & Laloui, 2014;Ng et al, 2014;Yavari et al, 2014;Saggu & Chakraborty, 2015;Suryatriyastuti et al, 2015;Ng et al, 2016;Vieira & Maranha, 2016), such a consideration suggesting the unsuitability of an elastic approach of analysis in those situations. Thermo-elastic analyses can be considered unsuitable also for situations that involve mechanisms and phenomena inducing plastic strain in the soil surrounding the piles irrespective of the magnitude of the applied loads.…”

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

confidence: 99%

“…Over the last decade, an increasing amount of research has investigated the impact of thermal loads on the thermomechanical behaviour of isolated energy piles, including a series of full-scale in situ tests (Laloui et al, 2003;BourneWebb et al, 2009;Akrouch et al, 2014;Wang et al, 2014;Sutman et al, 2015;You et al, 2016), centrifuge (Ng et al, 2014;Stewart & McCartney, 2014;Goode & McCartney, 2015;Ng et al, 2015) and model-scale (Kalantidou et al, 2012;Kramer & Basu, 2014;Yavari et al, 2014) experiments, and numerical analyses (Laloui et al, 2006;Suryatriyastuti et al, 2012;Mimouni & Laloui, 2014;Olgun et al, 2014;Batini et al, 2015;Rotta Loria et al, 2015;Saggu & Chakraborty, 2015). Several in situ tests (McCartney & Murphy, 2012;Murphy et al, 2014;Mimouni & Laloui, 2015) and numerical analyses (Di Donna & Laloui, 2014;Jeong et al, 2014;Salciarini et al, 2015;Di Donna et al, 2016;Suryatriyastuti et al, 2016) have recently investigated this problem for energy pile groups.…”

Section: Introductionmentioning

confidence: 99%

Thermally induced group effects among energy piles

Loria

2017

Géotechnique

144

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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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Cyclic Thermo-Mechanical Analysis of Energy Piles in Sand

Cited by 81 publications

References 24 publications

Assessment of Stress-Strain Behavior of Energy Piles Installed in Sand

Assessment of Stress-Strain Behavior of Energy Piles Installed in Sand

Axial and Radial Thermal Responses of a Field-Scale Energy Pile under Monotonic and Cyclic Temperature Changes

Thermally induced group effects among energy piles

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