Clayey slip surfaces control the reactivation and long-term deformation of slow-moving landslides and may experience thermal fluctuations from climate, seasonal ground-temperature changes, or subsurface heat sources. Experiments show that residual shear strength depends on temperature and shearing rate, yet most numerical approaches use temperature-independent strength parameters. We present a non-isothermal viscoplastic constitutive model for clayey slip surfaces implemented with zero-thickness interface elements. It includes temperature-dependent normal and tangential stiffness, progressive degradation of cohesion and friction angle, and rate-dependent viscoplastic slip governed by a non-associated flow rule. Coupling with hydraulic and thermal balance equations allows the interface response to evolve with stress state, temperature, aperture, and accumulated irreversible displacement. Validation against temperature-controlled drained ring-shear tests on bentonite and smectite-rich soils covers heating--cooling, cooling--heating, and combined thermal paths. The simulations reproduce thermal strengthening at slow shearing rates and thermal weakening or limited sensitivity at higher rates. Application to the Congress Street cut benchmark shows that zero-thickness elements improve the representation of strain localization and progressive failure. Increasing temperature progressively degrades interface strength, increases displacement, joint aperture, and shear strain, and accelerates sliding. Temperature-dependent interface degradation can therefore reduce the apparent stability margin of clayey slopes and should be included in slope-stability assessments involving thermal fluctuations.
S. Tourchi, E. Badakhshan, Milad Jabbarzadeh et al.· 1 citation
Understanding the thermally induced volumetric response of fine-grained soils is important for geo-energy systems, underground storage facilities, and radioactive waste repositories. This study examines the thermo-mechanical response of two natural silty clays from Budapest, Hungary, with different plasticity levels and stress histories. Slow-heating tests under drainage-promoting boundary conditions and heating-cooling cycle tests were performed using a temperature-controlled oedometer on low-plasticity (LP) and high-plasticity (HP) samples. The specimens were heated from [Formula: see text] to [Formula: see text] under different over-consolidation ratios, ranging from OCR = 1 to 22. The results show that normally consolidated samples contract during slow heating. Overconsolidated samples show a more variable response, indicating that OCR alone is not sufficient to describe the thermal volumetric behaviour. The HP samples generally developed larger thermal volumetric strains than the LP samples, showing the influence of plasticity on the magnitude of thermal deformation. The low-stress naturally overconsolidated specimens, LP12 and HP22, showed mainly contractive behaviour, although their response should be interpreted with caution because their OCR values were inferred from apparent preconsolidation pressures obtained from separate room-temperature oedometer tests. During repeated heating-cooling cycles, most irreversible volumetric strain developed during the first cycle, while later cycles showed smaller strain increments and a trend towards more recoverable behaviour. The tests were not independently verified as fully drained by pore-pressure measurements; therefore, the results are interpreted as laboratory-scale evidence under drainage-promoting conditions rather than as proof of a unique drained mechanism.
Hamed Hoseinimighani, S. Tourchi, A. Lavasan et al.· Scientific Reports· 1 citation
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