Critical State Constitutive Model for the Isotropic Thermal Compression of Structured Sand–Bentonite Buffers
By: Shirasb, Atena
.
Contributor(s): Karimi, Amir Hossein.
Publisher: New York Springer 2019Edition: Vol.49(4), Aug.Description: 398-408p.Subject(s): Construction Engineering and Management (CEM)Online resources: Click here
In:
Indian geotechnical journalSummary: The sand–bentonite mixture is used as the buffer layer in nuclear waste disposals. The buffer layer, as a non-permeable protective layer, is generally exposed to temperature gradients and the long-term subjection to temperature results in creep and more intact structure for the layer. In the present study, thermally induced structure and its effects on the isotropic compression behavior and volume change behavior of buffer layer are evaluated. Thermal consolidation tests were conducted using a modified triaxial cell capable of handling temperatures up to 90 °C. In order to investigate the effects of thermal gradients on the behavior of the mixture, saturated specimens were cured at constant temperatures of 40 °C, 60 °C and 80 °C, for time periods of 1, 3 and 5 days. Then, the consolidation tests were performed holding the curing temperature at a constant value up to end of the test. The results show that when the soil experiences higher temperatures for longer curing periods, the behavior of reconstituted soil is shifted from the reconstituted to a structured one which is an effect of induced creep in high-plasticity bentonite portion. Using the results of the tests performed in this study, a critical state-based constitutive model is proposed to simulate thermally induced volume change behavior of structured mixture. The capability of the proposed model is verified based on the experimental results and it is proved that the proposed model predictions are in good agreement with the experimental data.
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Articles Abstract Database
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School of Engineering & Technology (PG) Archieval Section | Not for loan | 2020406 |
The sand–bentonite mixture is used as the buffer layer in nuclear waste disposals. The buffer layer, as a non-permeable protective layer, is generally exposed to temperature gradients and the long-term subjection to temperature results in creep and more intact structure for the layer. In the present study, thermally induced structure and its effects on the isotropic compression behavior and volume change behavior of buffer layer are evaluated. Thermal consolidation tests were conducted using a modified triaxial cell capable of handling temperatures up to 90 °C. In order to investigate the effects of thermal gradients on the behavior of the mixture, saturated specimens were cured at constant temperatures of 40 °C, 60 °C and 80 °C, for time periods of 1, 3 and 5 days. Then, the consolidation tests were performed holding the curing temperature at a constant value up to end of the test. The results show that when the soil experiences higher temperatures for longer curing periods, the behavior of reconstituted soil is shifted from the reconstituted to a structured one which is an effect of induced creep in high-plasticity bentonite portion. Using the results of the tests performed in this study, a critical state-based constitutive model is proposed to simulate thermally induced volume change behavior of structured mixture. The capability of the proposed model is verified based on the experimental results and it is proved that the proposed model predictions are in good agreement with the experimental data.
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