Water retention of a bentonite for deep geological radioactive waste repositories: High-temperature experiments and thermodynamic modeling

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F20%3A10415796" target="_blank" >RIV/00216208:11310/20:10415796 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=sZVNuc0bBe" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=sZVNuc0bBe</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.enggeo.2020.105549" target="_blank" >10.1016/j.enggeo.2020.105549</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Water retention of a bentonite for deep geological radioactive waste repositories: High-temperature experiments and thermodynamic modeling

Popis výsledku v původním jazyce

Thermo-hydro-mechanical coupling is relevant in various natural processes and engineering applications involving clay soils. It can affect slope deformations and stability, as well as the functioning of clay barriers and energy piles. Temperature changes can alter the water retention capacity of expansive clays and, in turn, produce pressure, strength, and volume changes. In deep geological repositories, for instance, the design of bentonite buffers and the study of their interaction with the host formation must account for the heat released by radioactive decay. Here, to investigate how temperature controls the water retention capacity, vapor transfer experiments under adsorption/desorption (wetting/drying) paths were performed on the Czech B75 bentonite. The tests were conducted in a wide range of temperatures (20-80 degrees C) and initial dry densities (0.6-1.9 g/cm(3)), at high total suction (4-400 MPa), without mechanical loads. The results showed a systematic loss of water retention capacity at high temperature, particularly at low suction, irrespective of the initial compaction. To predict the behavior at any temperature, a model was constructed from the Clausius-Clapeyron and the Guggenheim-Anderson-de Boer equations. It was calibrated and validated at various temperatures, also on a different bentonite (without further tuning), showing good performance. Dry density-specific calibrations did not affect the model predictions significantly, consistently with results that exclude an effect of initial compaction on water retention at high suction. The proposed model seems suitable for inclusion into thermo-hydraulic descriptions in comprehensive constitutive frameworks for expansive clays, potentially improving the understanding of some behaviors related to thermo-hydro-mechanical coupling.

Název v anglickém jazyce

Water retention of a bentonite for deep geological radioactive waste repositories: High-temperature experiments and thermodynamic modeling

Popis výsledku anglicky

Thermo-hydro-mechanical coupling is relevant in various natural processes and engineering applications involving clay soils. It can affect slope deformations and stability, as well as the functioning of clay barriers and energy piles. Temperature changes can alter the water retention capacity of expansive clays and, in turn, produce pressure, strength, and volume changes. In deep geological repositories, for instance, the design of bentonite buffers and the study of their interaction with the host formation must account for the heat released by radioactive decay. Here, to investigate how temperature controls the water retention capacity, vapor transfer experiments under adsorption/desorption (wetting/drying) paths were performed on the Czech B75 bentonite. The tests were conducted in a wide range of temperatures (20-80 degrees C) and initial dry densities (0.6-1.9 g/cm(3)), at high total suction (4-400 MPa), without mechanical loads. The results showed a systematic loss of water retention capacity at high temperature, particularly at low suction, irrespective of the initial compaction. To predict the behavior at any temperature, a model was constructed from the Clausius-Clapeyron and the Guggenheim-Anderson-de Boer equations. It was calibrated and validated at various temperatures, also on a different bentonite (without further tuning), showing good performance. Dry density-specific calibrations did not affect the model predictions significantly, consistently with results that exclude an effect of initial compaction on water retention at high suction. The proposed model seems suitable for inclusion into thermo-hydraulic descriptions in comprehensive constitutive frameworks for expansive clays, potentially improving the understanding of some behaviors related to thermo-hydro-mechanical coupling.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Engineering Geology

ISSN

0013-7952

e-ISSN

—

Svazek periodika

269

Číslo periodika v rámci svazku

May

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

14

Strana od-do

105549

Kód UT WoS článku

000525399100012

EID výsledku v databázi Scopus

2-s2.0-85079858805