Numerical study for thermo-hydro-mechanical behavior of ground source heat pump system using pile foundation

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K04597
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Osaka Sangyo University (2021-2022); Kyoto University (2019-2020)
• Principal Investigator: Kimoto Sayuri 大阪産業大学, 工学部, 教授 (70362457)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 地中熱 / 杭基礎 / 熱弾粘塑性 / 粘性土 / 数値解析

Outline of Final Research Achievements

In this research, a thermo-fluid-mechanics coupled analysis method was developed, in which the thermal expansion of the ground and the structure (pile foundation), the thermal expansion and fluid flow, and the coupled behavior of soil skeleton deformation when using a geothermal heat pump system (energy pile) using pile foundation are investigated. The pile (reinforced concrete) was modeled as a thermo-elastic solid element, and the ground was modeled as a three-phase material with the soil skeleton as a thermo-elasto-viscoplastic body. In addition, using the developed analysis method, the basic mechanical behavior when using geothermal heat when the pile foundation was installed in the alluvial clay layer, was investigated. The ground model the material constants were determined referring to the reproduction analysis of the demonstration test by Laloui et al (2006).

Free Research Field

地盤力学、地盤工学

Academic Significance and Societal Importance of the Research Achievements

国内で地中熱を利用したヒートポンプシステムの導入事例が増えつつあり、今後も利用促進が期待される。わが国の軟弱粘性土地盤で利用する場合、加熱-冷却に伴う杭基礎の熱膨潤と圧縮、粘性土の温度上昇による圧密沈下など、杭基礎-地盤の複雑な相互作用による支持力低下や地盤変形が懸念されるが，本研究で開発した手法によりわが国でエネルギーパイルを利用する場合の地盤変形挙動の予測が可能であり、エネルギーパイルの普及促進に寄与するものと考える。