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

Takato Takemura, Minoru Sato, Takashi Chiba, Kyota Uemura, Yoshiharu Ito, Ayako Funabiki

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)191-203
Number of pages13
JournalBulletin of Engineering Geology and the Environment
Volume76
Issue number1
DOIs
Publication statusPublished - 1 Feb 2017

Keywords

  • GSHP
  • Magnetic susceptibility
  • Thermal conductivity
  • Volcanic sediment

Fingerprint

Dive into the research topics of 'Effect of sedimentary facies and geological properties on thermal conductivity of Pleistocene volcanic sediments in Tokyo, central Japan'. Together they form a unique fingerprint.

Cite this