Thermo-hydro-mechanical modelling of rock cliff-atmosphere interaction: the case of the Pozary test site in Czechia

Understanding how the rapidly changing climatic forcing is affecting the complex mechanical interactions between rock masses is crucial for assessing the stability of rock slopes and correctly quantifying the associated hazard and risk. Volumetric changes induced by temperature fluctuations cause seasonal cycles of swelling and contraction, potentially resulting in crack formation and propagation (Tourchi, 2023; Jabbarzadeh et al., 2023). Further couplings complicate the picture, and reliable fully-coupled modelling approaches are lacking. This study presents a numerical simulation of quartz diorite rock cliff-atmosphere interactions. The developed numerical model employs a fully coupled thermo-hydro-mechanical (THM) approach, incorporating solid, water, and energy balance equations alongside thermal, hydraulic, and mechanical constitutive equations (Tourchi et al., 2021; Tourchi et al., 2023). The geometry of the fractured rock cliff was accurately captured in a previous study, where researchers conducted precise field measurements at the 'Požáry test site', a newly established field laboratory for the investigation of fractured rock masses (Racek et al., 2023). This research utilized a cutting-edge monitoring system to tracks temperature fluctuations and displacement changes, offering critical insights into the thermo-hydro-mechanical (THM) processes occurring within the rock mass and their subsequent impact on the stability of the rock cliff. These gauges have also monitored potential plastic strain over microfractures during a two-month observation period. Initial and boundary conditions for analysis, as well as material parameters, are determined from available field and laboratory experimental results. The thermal, hydraulic, and mechanical observations for three different observation points where compare with computed results. Despite limitations in input parameters, the simulation results exhibit a promising agreement with field measurements. The performance and analysis of the in situ test can significantly enhanced the understanding of a complex THM problem and can proved the capability of the numerical formulation to provide adequate modelling capacity. References Jabbarzadeh, M., Sadeghi, H., Tourchi, S. and Darzi, A.G., 2023. Thermo-hydraulic analysis of desiccation cracked soil strata considering ground temperature and moisture dynamics under the influence of soil-atmosphere interactions. Racek, O., Balek, J., Loche, M., Vích, D. and Blahůt, J., 2023. Rock surface strain in situ monitoring affected by temperature changes at the Požáry field lab (Czechia). Sensors, 23(4), 2237. Tourchi, S., Mánica, M.A., Gens, A., Vaunat, J., Vu, M.N. and Armand, G., 2023. A thermomechanical model for argillaceous hard soils–weak rocks: application to THM simulation of deep excavations in claystone. Géotechnique, pp.1-14. Tourchi, S., Vaunat, J., Gens, A., Bumbieler, F., Vu, M.N. and Armand, G., 2021. A full-scale in situ heating test in Callovo-Oxfordian claystone: observations, analysis and interpretation. Computers and Geotechnics, 133, p.104045.