Thermo-mechanical behavior of cast-in-place energy piles

Chihun Sung, Sangwoo Park, Seokjae Lee, Kwanggeun Oh, Hangseok Choi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

An energy pile induces heat exchange with the ground formation by circulating heat carrier fluid through a heat exchange pipe, which is encased in pile foundation. During heat exchange, temperature variation in energy pile generates thermally-induced stress due to the different thermo-mechanical behavior between the pile and surrounding ground, and the restriction of pile deformation. A series of full-scale field tests was performed to identify the thermo-mechanical behavior of a cast-in-place energy pile equipped with 5-pair-parallel U-type heat exchange pipe. During the field investigation, each cooling and heating test lasted for 30 days, including a 15-day operating period and 15-day resting period, and the thermal stress generated in the energy pile was monitored. The maximum thermal stress was evaluated to be 2.6 MPa in the cooling test, which is about 10% of the design compressive strength of concrete. In addition, a finite element (FE) numerical model was developed to simulate the thermo-mechanical behavior of the energy pile. In the numerical analysis, relevant boundary conditions and interface model were determined by comparing with the field measurement. Finally, a parametric study was performed to estimate the thermal stress and deformation of a cast-in-place energy pile for various ground conditions.

Original languageEnglish
Pages (from-to)920-938
Number of pages19
JournalEnergy
Volume161
DOIs
Publication statusPublished - 2018 Oct 15

Fingerprint

Piles
Thermal stress
Pipe
Cooling
Pile foundations
Compressive strength
Interfaces (computer)
Numerical analysis
Numerical models
Hot Temperature
Boundary conditions
Concretes
Heating
Fluids

Keywords

  • Cast-in-place energy pile
  • Ground heat exchanger
  • Numerical analysis
  • Thermal stress
  • Thermo-mechanical coupled analysis

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Pollution
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

Cite this

Thermo-mechanical behavior of cast-in-place energy piles. / Sung, Chihun; Park, Sangwoo; Lee, Seokjae; Oh, Kwanggeun; Choi, Hangseok.

In: Energy, Vol. 161, 15.10.2018, p. 920-938.

Research output: Contribution to journalArticle

Sung, Chihun ; Park, Sangwoo ; Lee, Seokjae ; Oh, Kwanggeun ; Choi, Hangseok. / Thermo-mechanical behavior of cast-in-place energy piles. In: Energy. 2018 ; Vol. 161. pp. 920-938.
@article{bdaa24cd0fe941738fa3f3c720a926c2,
title = "Thermo-mechanical behavior of cast-in-place energy piles",
abstract = "An energy pile induces heat exchange with the ground formation by circulating heat carrier fluid through a heat exchange pipe, which is encased in pile foundation. During heat exchange, temperature variation in energy pile generates thermally-induced stress due to the different thermo-mechanical behavior between the pile and surrounding ground, and the restriction of pile deformation. A series of full-scale field tests was performed to identify the thermo-mechanical behavior of a cast-in-place energy pile equipped with 5-pair-parallel U-type heat exchange pipe. During the field investigation, each cooling and heating test lasted for 30 days, including a 15-day operating period and 15-day resting period, and the thermal stress generated in the energy pile was monitored. The maximum thermal stress was evaluated to be 2.6 MPa in the cooling test, which is about 10{\%} of the design compressive strength of concrete. In addition, a finite element (FE) numerical model was developed to simulate the thermo-mechanical behavior of the energy pile. In the numerical analysis, relevant boundary conditions and interface model were determined by comparing with the field measurement. Finally, a parametric study was performed to estimate the thermal stress and deformation of a cast-in-place energy pile for various ground conditions.",
keywords = "Cast-in-place energy pile, Ground heat exchanger, Numerical analysis, Thermal stress, Thermo-mechanical coupled analysis",
author = "Chihun Sung and Sangwoo Park and Seokjae Lee and Kwanggeun Oh and Hangseok Choi",
year = "2018",
month = "10",
day = "15",
doi = "10.1016/j.energy.2018.07.079",
language = "English",
volume = "161",
pages = "920--938",
journal = "Energy",
issn = "0360-5442",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Thermo-mechanical behavior of cast-in-place energy piles

AU - Sung, Chihun

AU - Park, Sangwoo

AU - Lee, Seokjae

AU - Oh, Kwanggeun

AU - Choi, Hangseok

PY - 2018/10/15

Y1 - 2018/10/15

N2 - An energy pile induces heat exchange with the ground formation by circulating heat carrier fluid through a heat exchange pipe, which is encased in pile foundation. During heat exchange, temperature variation in energy pile generates thermally-induced stress due to the different thermo-mechanical behavior between the pile and surrounding ground, and the restriction of pile deformation. A series of full-scale field tests was performed to identify the thermo-mechanical behavior of a cast-in-place energy pile equipped with 5-pair-parallel U-type heat exchange pipe. During the field investigation, each cooling and heating test lasted for 30 days, including a 15-day operating period and 15-day resting period, and the thermal stress generated in the energy pile was monitored. The maximum thermal stress was evaluated to be 2.6 MPa in the cooling test, which is about 10% of the design compressive strength of concrete. In addition, a finite element (FE) numerical model was developed to simulate the thermo-mechanical behavior of the energy pile. In the numerical analysis, relevant boundary conditions and interface model were determined by comparing with the field measurement. Finally, a parametric study was performed to estimate the thermal stress and deformation of a cast-in-place energy pile for various ground conditions.

AB - An energy pile induces heat exchange with the ground formation by circulating heat carrier fluid through a heat exchange pipe, which is encased in pile foundation. During heat exchange, temperature variation in energy pile generates thermally-induced stress due to the different thermo-mechanical behavior between the pile and surrounding ground, and the restriction of pile deformation. A series of full-scale field tests was performed to identify the thermo-mechanical behavior of a cast-in-place energy pile equipped with 5-pair-parallel U-type heat exchange pipe. During the field investigation, each cooling and heating test lasted for 30 days, including a 15-day operating period and 15-day resting period, and the thermal stress generated in the energy pile was monitored. The maximum thermal stress was evaluated to be 2.6 MPa in the cooling test, which is about 10% of the design compressive strength of concrete. In addition, a finite element (FE) numerical model was developed to simulate the thermo-mechanical behavior of the energy pile. In the numerical analysis, relevant boundary conditions and interface model were determined by comparing with the field measurement. Finally, a parametric study was performed to estimate the thermal stress and deformation of a cast-in-place energy pile for various ground conditions.

KW - Cast-in-place energy pile

KW - Ground heat exchanger

KW - Numerical analysis

KW - Thermal stress

KW - Thermo-mechanical coupled analysis

UR - http://www.scopus.com/inward/record.url?scp=85053077378&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85053077378&partnerID=8YFLogxK

U2 - 10.1016/j.energy.2018.07.079

DO - 10.1016/j.energy.2018.07.079

M3 - Article

VL - 161

SP - 920

EP - 938

JO - Energy

JF - Energy

SN - 0360-5442

ER -