Iranian Journal of Geophysics

Iranian Journal of Geophysics

Investigating the effect of thermal loading on geothermal piles in stratified soils

Document Type : Research Article

Authors
Masoud Amelsakhi
Fatemeh Sheshpari
Master of Civil Engineering, Department of Civil Engineering, Faculty of Engineering, Qom University of Technology, Qom, Iran
10.30499/ijg.2024.423290.1549
Abstract
Energy pile is a type of foundation that simultaneously provides the two goals of structural load transfer and energy conversion. In addition to transferring the structural load of the building to the lower layers, this system also acts as a heat exchanger. In this article, to investigate the effect of soil and geothermal pile on each other, numerical modeling was performed using finite element method using COMSOL software. The main purpose of this study is to investigate the response of geothermal pile in layered soils and compare it with geothermal pile implemented in homogeneous soil. This problem has been performed considering the different soil layers that are on the bedrock and the results have been compared with the experimental data of the geothermal pile placed in the layered soil. The results showed that the properties of soils and the location of loose and dense
layers in the depth of the soil have a significant effect on the type of behavior of the pile, so the deformations and stresses obtained from the numerical analyzes are related to the modulus of
elasticity and in other words, to the hardness of the soil. It conducted that the value of the strain obtained from the numerical analysis of the pile placed in multi-layered soil is between the value of the pile strains in the case where the homogeneous soil is only loose or dense. The conclusion of obtained results is that the vertical stresses and strains of the pile placed in multi-layered soil at the depth of the earth's surface are in better agreement with the vertical stresses and strains of the pile placed in loose soil. The modulus of elasticity of soil with average density of type 2 is 74% higher than the modulus of elasticity of loose soil considered in the analysis, which has led to a 27%
reduction in displacement, a 40% increase in compressive stress and a 77% reduction in vertical strain. The same change in the modulus of elasticity of the soil layers caused a change in the values of stresses and pile stresses in the state of layered soil. Also, the 40% change in the modulus of elasticity of type 2 and 3 soils has caused the amount of displacement to decrease by 17% and the amount of compressive stress and strain to increase by 11% and decrease by 27%, respectively. The results of the numerical analysis showed that the type of soil and the way it is located in the depth have a significant effect on the behavior of the geothermal pile.
 
Keywords
Geothermal energy pile
FEM
COMSOL
renewable energy

Subjects

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Iranian Journal of Geophysics
Volume 18, Issue 6
January and February 2025
Pages 17-28