Abstract
The quantitative studies of time-lapse electrical resistivity data for characterizing coupled thermal-hydro-mechanical processes in bentonite
American Geophysical Union Fall Meeting, Vol.2022
American Geophysical Union 2022 fall meeting
12/2022
Abstract
Bentonite has been considered as a backfill and sealing material for long-term deep geological storage of high-level radioactive waste (HLW). Heat-emanating radioactive waste plus groundwater infiltration from the host rock trigger complex coupled THM (thermal-hydrological-mechanical) processes in the bentonite barrier system, which are tightly related to the safety of the HLW repository. It is thus important to improve the understanding and the monitoring capability of THM processes in bentonite, particularly under high temperature heating. Time-lapse electrical resistivity tomography (ERT) has been recognized as a potential geophysical method to monitor the HLW repository due to its strength in providing spatial-temporal resistivity distribution that is correlated to the THM properties of the bentonite. However, to quantitively interpret the THM processes from ERT surveys, the link between resistivity and THM properties needs to be established. In this study, we investigate this relationship with two laboratory column tests: one undergoing both heating and hydration, and the other one only subject to hydration. Two column tests are monitored by the time-lapse ERT, X-ray CT imaging and thermocouples for nearly one year. We adopt an advanced time-lapse inversion algorithm with both structural and time-space constraints to invert the measured resistivity data. The inverted spatial-temporal resistivity images are jointly analyzed with the bulk density from the X-ray CT and the temperature distribution. The results show that the temporal changes of resistivity and density have similar trends in both columns, and the spatial distribution of resistivity corresponds well to the temperature distribution. We choose different temperature zones to perform quantitative analyses of the temporal changes in resistivity and density and identify some empirical relations that may benefit ERT's application in field site monitoring. The laboratory column experiments provide valuable insights into the understanding of ERT datasets during field experiments.
Details
- Title: Subtitle
- The quantitative studies of time-lapse electrical resistivity data for characterizing coupled thermal-hydro-mechanical processes in bentonite
- Creators
- Hang Chen - Boise State UniversityChunwei ChouSharon E. BorglinChun ChangTimothy J. KneafseySeiji NakagawaLiange ZhengJens BirkholzerYuxin Wu
- Resource Type
- Abstract
- Publication Details
- American Geophysical Union Fall Meeting, Vol.2022
- Conference
- American Geophysical Union 2022 fall meeting
- Publisher
- American Geophysical Union
- Alternative title
- AGU 2022 fall meeting
- Language
- English
- Date published
- 12/2022
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984962624602771
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