Effect of sedimentary facies and geological properties on thermal conductivity of Pleistocene volcanic sediments in Tokyo, central Japan

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• 作者：Takato Takemura ; Minoru Sato ; Takashi Chiba…
• 关键词：Thermal conductivity ; Magnetic susceptibility ; Volcanic sediment ; GSHP
• 刊名：Bulletin of Engineering Geology and the Environment
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：76
• 期：1
• 页码：191-203
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geotechnical Engineering & Applied Earth Sciences; Geoengineering, Foundations, Hydraulics; Geoecology/Natural Processes; Nature Conservation;
• 出版者：Springer Berlin Heidelberg
• ISSN：1435-9537
• 卷排序：76

文摘

When ground source heat pump systems are installed underground, an estimate of the thermal conductivity is required to determine the desired total length of the heat exchanger (U-tube). Many large cities in Asia are built on Quaternary sediments, but the thermal conductivity of these sediments is not well understood. To measure the thermal conductivity of Pleistocene volcanic sediments in Tokyo, Japan, we discuss methods of measuring thermal conductivity and factors influencing the thermal conductivity of volcanic sediment, which has low quartz content. The results obtained from experiments using a drill core, borehole data and artificial sediment samples are as follows: (1) values of thermal conductivity predicted using water content, porosity or sand content can be underestimated in volcanic sediment or sediments with large amounts of magnetic minerals; (2) magnetic minerals have a higher thermal conductivity than quartz, so there is a relationship between magnetic susceptibility and thermal conductivity: (3) comparison of thermal conductivity measurements performed using box- and needle-type probes showed that the values measured using the former are comparatively larger. This decrease in thermal conductivity is explained by formation of air-filled cracks when the needle penetrates the sediment, as air has a lower thermal conductivity than sediment.