Improvement of understanding multi-scale and non-equilibrium heat and water flows in soils during freezing and thawing processes

2016 Fiscal Year Final Research Report

• Project/Area Number: 26450338
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Rural environmental engineering/Planning
• Research Institution: Mie University
• Principal Investigator: Watanabe Kunio 三重大学, 生物資源学研究科, 教授 (10335151)
• Co-Investigator(Renkei-kenkyūsha): MUTO Yoshiko 岩手大学, 農学部, 准教授 (60436053)
• Research Collaborator: FLURY Markus ; SIMUNEK Jiri ; BAN Toshikazu ; NAKANISHI Maki ; KUGISAKI Yuki ; OSADA Yurie ; TAKEUCHI Megumi
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 凍土 / 土壌凍結層 / 水分移動 / 熱移動 / 浸潤 / 水ポテンシャル / 不凍水 / 透水係数

Outline of Final Research Achievements

To understand heat and water flows in freezing and thawing soils, column experiments and numerical analysis were performed. Fluctuation of water potential in non-equilibrium state near freezing front was directly observed. And, hysteresis in unfrozen water curve, hydraulic conductivity of frozen soil, retardation of soil freezing by macropores, blocking of the macropores by ice, and effect of the macropores on soil thawing were clarified. For modeling of soil freezing and thawing processes, extension method of conventional 1D model to 3D phenomena, and applying method of apparent thermal conductivity and hydraulic conductivity were proposed. Then, we summarized the issues in the current soil freezing model, such as non-equilibrium melting of soil pore ice and re-freezing of infiltrated water, which should be studied in future.

Free Research Field

土壌物理学