Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Evening Poster

S (Solid Earth Sciences) » S-CG Complex & General

[S-CG57] Dynamics in mobile belts

Wed. May 23, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Yukitoshi Fukahata(Disaster Prevention Research Institute, Kyoto University), Toru Takeshita(Department of Natural History Sciences, Graduate School of Science, Hokkaido University), Hikaru Iwamori(海洋研究開発機構・地球内部物質循環研究分野)

[SCG57-P27] Change of pore connectivity in granular materials under confining pressures

Minako Nambu1, Tohru Watanabe1, *MAREMICHI ABE1 (1.University of Toyama)

Keywords:pore, connectivity, granular material

The pore connectivity in Berea sandstone (porosity~20%) is remarkably reduced under confining pressures. Electrical conductivity in Berea sandstone decreased by 22% as the confining pressure was increased to 40 MPa, while the pore-fluid pressure was kept at atmospheric pressure (0.1 MPa). Measured volumetric strain showed that the change in porosity under the confining pressure was less than 1%. The observed relatively large decrease in conductivity requires a significant decrease in the connectivity of pores. The effective medium theory (Kirkpatrick, 1973) suggests that around 20% of conduction paths must be closed to decrease conductivity by 22%. The observation of pore structures with X-ray CT revealed that a lot of thin pores were involved in a network of pores. These thin pores are likely to close under confining pressures to reduce electrical conductivity. Compression tests on packed quartz sand also showed that a small decrease in porosity causes a relatively large decrease in conductivity.