Project  Description: The objectives of this project are to characterize the effects of high temperatures (up to 200 °C) on the mechanisms and material properties governing coupled heat transfer, water flow, and volume change in unsaturated, compacted granular bentonite, and to understand and simulate the multiphase hydration process of bentonite buffers in deep geological repositories with closely spaced waste packages or Dual Purpose Containers. 

The project tasks include a combination of element-scale testing to measure bentonite material properties under high temperatures, tank-scale testing to capture the coupled processes during bentonite hydration under high temperatures, development of quantitative relationships to represent the experimentally-observed thermo-hydro-mechanical behavior, and numerical simulations of bentonite buffer hydration involving high temperatures for different initial densities and rates of water supply from the host rock. In the element-scale tests, different thermo-hydro-mechanical paths are being applied to compacted bentonite specimens having different initial conditions (density and degree of saturation) in thermal triaxial cells to collect data needed to define the new constitutive relationships. 

Publications: 

McCartney, J.S. (2022). “Water retention in expansive clays under elevated temperatures and constrained conditions.” Proc. GeoCongress 2022. Charlotte. Mar. 20-23. GSP 335, ASCE, Reston, VA. 315-324.

Lu, Y. and McCartney, J.S. (2022). “Physical modeling of coupled thermo-hydraulic behavior of compacted MX80 bentonite during heating.” Geotechnical Testing Journal. 10.1520/GTJ20220054.

He, X., Baek, J., and McCartney, J.S., Chen, J.S. (2022). “Machine-learned physics-informed constitutive modeling for path-dependent materials.” 2022 EMI Conference. Baltimore, MD. May 31-3. 1 pg.

He, X., Chen, J.S. (2022) “Thermodynamically consistent machine-learned internal state variable approach for data-driven modeling of path-dependent materials.” CMAME. 402, 115348.

He, X., Baek, J., and McCartney, J.S., Chen, J.S. (2023). “A machine-learned non-isothermal soil water retention model for modeling thermo-hydro-mechanical behavior of bentonite with high temperature gradient using meshfree method. 2nd IACM MMLDE-CSET. Sep. 24-27, 2023. 

Lu, Y. and McCartney, J.S. (2023). “Insights into the thermo-hydraulic properties of compacted MX80 bentonite during hydration under elevated temperature.” Canadian Geotechnical Journal. DOI: 10.1139/cgj-2022-0537.

Musa, M., Lu, Y. and McCartney, J.S. (2023). "Thermal conductivity function with physics-based parameters." 8th International Conference on Unsaturated Soils, Milos Island, Greece. May 2-5. UNSAT 2023, E3S Web of Conferences, Les Ulis, France. 382, 06005. 1-6.  DOI: 10.1051/e3sconf/202338206005.

Lu, Y. and McCartney, J.S. (2023). “Thermal conductivity function for unsaturated soils linked with water retention by capillarity and adsorption.” Journal of Geotechnical and Geoenvironmental Engineering. DOI: 10.1061/JGGEFK/GTENG-11669.

Baek, J., He, X., Yang, Y., Lu, Y., McCartney, J.S., and Chen, J.S. (2024). “Data-driven modeling of an unsaturated bentonite buffer model test under high temperatures using an enhanced axisymmetric reproducing kernel particle method.” Computers and Geotechnics. 168, 106133. DOI: 10.1016/j.compgeo.2024.106133. 

Lu, Y. and McCartney, J.S. (2024). “Temperature effects on adsorption and capillary water retention mechanisms in constrained unsaturated soils.” Acta Geotechnica. DOI: 10.1007/s11440-024-02341-9.