Numerical analyses of coupled thermal–hydraulic–mechanical–chemical​ processes for estimating permeability change in fractured rock induced by alkaline solution

Ogata, Sho; Yasuhara, Hideaki; Kinoshita, Naoki; Inui, Toru; Nishira, Eita; Kishida, Kiyoshi

doi:https://doi.org/10.1016/j.gete.2022.100372

Numerical analyses of coupled thermal–hydraulic–mechanical–chemical processes for estimating permeability change in fractured rock induced by alkaline solution

Ogata, Sho; Yasuhara, Hideaki; Kinoshita, Naoki et al.

Geomechanics for Energy and the Environment, 2022, 31, 100372

Number of Access:545（2025-07-27 01:22 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/92441

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Title	Numerical analyses of coupled thermal–hydraulic–mechanical–chemical processes for estimating permeability change in fractured rock induced by alkaline solution
Creator	NRID 1000050868388 1000050868388 researchmap permalink 20191001 20191001 Scopus Author ID 57188767826 57188767826 CreatorName Ogata, Sho
	NRID 1000070432797 1000070432797 CreatorName Yasuhara, Hideaki
	NRID 1000030263958 1000030263958 CreatorName Kinoshita, Naoki
	NRID 1000090324706 1000090324706 researchmap permalink read0066428 read0066428 Scopus Author ID 7203009205 7203009205 CreatorName Inui, Toru
	CreatorName Nishira, Eita
	NRID 1000020243066 1000020243066 CreatorName Kishida, Kiyoshi
Subject	Coupled THMC numerical model
	Fracture initiation/propagation
	Inflow of alkaline solution
	Permeability of fractured rock
	pH of groundwater
	Pressure solution
Description	Ogata S., Yasuhara H., Kinoshita N., et al. Numerical analyses of coupled thermal–hydraulic–mechanical–chemical processes for estimating permeability change in fractured rock induced by alkaline solution. Geomechanics for Energy and the Environment 31, 100372 (2022); https://doi.org/10.1016/j.gete.2022.100372.
Abstract	The chemical condition of groundwater, such as the pH, affects the rate of the mineral-groundwaterreactions which may alter the permeability of rock masses with time. A numerical model that can address the permeability evolution of rock masses, containing newly generated fractures due to geochemical processes depending on the pH, is proposed by upgrading our coupled THMC model, IPSACC. Subsequently, the proposed model is utilized to estimate the long-term permeability evolution of a natural barrier composed of granite within a geological repository under subsurface conditions, considering the inflow of the alkaline cement solution from an artificial barrier which is virtually installed in a disposal cavity of HLW. In particular, a quantitative evaluation of the impact of the inflow of the alkaline cement solution on the change in permeability in the fractured rock is the novelty of this work. The computed predictions show that the fractures generated during the cavity excavation drastically increase the rock permeability near the cavity and that the rapid permeability reduction within the several shear-induced fractures is the result of the pressure solution at the contacting asperities of the fractures after the disposal of the radioactive waste into the disposal cavity. The reduction of the fracture permeability is enhanced by the increase in the pressure solution rate due to the spreading of the alkaline solution only close to the disposal cavity, while there was no enhancement in the fractures, except for close to the disposal cavity, because the alkaline solution cannot reach the fractures before the pressure solution reaches the equilibrium state within an early period after the disposal of the HLW. From these results, in the geological environment assumed in this study, it is expected that the performance of a natural barrier for delaying the migration of radionuclides over the long duration may be almost unaffected by the inflow of the alkaline solution from an artificial barrier because its impact on the permeability evolution of a natural barrier is spatiotemporally limited.
Publisher	Elsevier Ltd
Source Title	Geomechanics for Energy and the Environment
Volume (Issue)	31
Page	100372
Date of Issued	2022-09-01
Language	English
Handle URL	https://hdl.handle.net/11094/92441
eISSN	23523808
Relation.isVersionOf	DOI (Publisher Version) https://doi.org/10.1016/j.gete.2022.100372
Access Rights	open access
CopyRight	© 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/
oaire:version	Accepted Manuscript
Category	学術雑誌論文 Journal Article

Resource Type	journal article
Local Type	Journal Article
DCMI Type	Text
DCTERMS.bibliographicCitation	Geomechanics for Energy and the Environment. 2022, 31, p. 100372
DC.title	Numerical analyses of coupled thermal–hydraulic–mechanical–chemical processes for estimating permeability change in fractured rock induced by alkaline solution
DC.creator	Ogata, Sho
	Yasuhara, Hideaki
	Kinoshita, Naoki
	Inui, Toru
	Nishira, Eita
	Kishida, Kiyoshi
DC.publisher	Elsevier Ltd
DC.language' scheme='DCTERMS.RFC1766	English
DC.type' scheme='DCTERMS.DCMIType	Text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2022-09-01
DC.identifier	https://doi.org/10.1016/j.gete.2022.100372
DC.subject	Coupled THMC numerical model
	Fracture initiation/propagation
	Inflow of alkaline solution
	Permeability of fractured rock
	pH of groundwater
	Pressure solution
DC.description	Ogata S., Yasuhara H., Kinoshita N., et al. Numerical analyses of coupled thermal–hydraulic–mechanical–chemical processes for estimating permeability change in fractured rock induced by alkaline solution. Geomechanics for Energy and the Environment 31, 100372 (2022); https://doi.org/10.1016/j.gete.2022.100372.
DCTERMS.abstract	The chemical condition of groundwater, such as the pH, affects the rate of the mineral-groundwaterreactions which may alter the permeability of rock masses with time. A numerical model that can address the permeability evolution of rock masses, containing newly generated fractures due to geochemical processes depending on the pH, is proposed by upgrading our coupled THMC model, IPSACC. Subsequently, the proposed model is utilized to estimate the long-term permeability evolution of a natural barrier composed of granite within a geological repository under subsurface conditions, considering the inflow of the alkaline cement solution from an artificial barrier which is virtually installed in a disposal cavity of HLW. In particular, a quantitative evaluation of the impact of the inflow of the alkaline cement solution on the change in permeability in the fractured rock is the novelty of this work. The computed predictions show that the fractures generated during the cavity excavation drastically increase the rock permeability near the cavity and that the rapid permeability reduction within the several shear-induced fractures is the result of the pressure solution at the contacting asperities of the fractures after the disposal of the radioactive waste into the disposal cavity. The reduction of the fracture permeability is enhanced by the increase in the pressure solution rate due to the spreading of the alkaline solution only close to the disposal cavity, while there was no enhancement in the fractures, except for close to the disposal cavity, because the alkaline solution cannot reach the fractures before the pressure solution reaches the equilibrium state within an early period after the disposal of the HLW. From these results, in the geological environment assumed in this study, it is expected that the performance of a natural barrier for delaying the migration of radionuclides over the long duration may be almost unaffected by the inflow of the alkaline solution from an artificial barrier because its impact on the permeability evolution of a natural barrier is spatiotemporally limited.
DC.rights	© 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/
DC.format	92441
citation_title	Numerical analyses of coupled thermal–hydraulic–mechanical–chemical processes for estimating permeability change in fractured rock induced by alkaline solution
citation_author	Ogata, Sho
	Yasuhara, Hideaki
	Kinoshita, Naoki
	Inui, Toru
	Nishira, Eita
	Kishida, Kiyoshi
citation_publisher	Elsevier Ltd
citation_language	English
citation_date	2022-09-01
citation_journal_title	Geomechanics for Energy and the Environment
citation_volume	31
citation_firstpage	100372
citation_doi	https://doi.org/10.1016/j.gete.2022.100372
citation_public_url	https://hdl.handle.net/11094/92441

Numerical analyses of coupled thermal–hydraulic–mechanical–chemical​ processes for estimating permeability change in fractured rock induced by alkaline solution

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Numerical analyses of coupled thermal–hydraulic–mechanical–chemical processes for estimating permeability change in fractured rock induced by alkaline solution