The behaviour of soils subject to suction on drying and wetting paths depends on the type of material and its initial state. Exposure to heat modifies the state of pore water and therefore the hydromechanical behaviour of the soil. A new experimental device has been developed to study the thermohydric behaviour of unsaturated soils. Salt solution desiccators and polyethylene glycol (PEG) osmotic solutions are dipped in thermostatic baths, whose temperature ranges from room temperature to 80 °C. Tests were carried out on a sandy clay prepared in the laboratory and on a natural undisturbed clay, extracted from an experimental site for deep underground storage of radioactive waste. Results show that temperature plays an important role in the shrinkage of soil, especially when subjected to high levels of suction. The results can be applied to observe the response of confining clay barriers submitted to hydric and thermal changes.
Thermomechanical couplings in the consolidation of an unsaturated clayey silty sand are investigated. The couplings are analysed through the influence of the temperature (relative to the total vertical stress) on the mechanical characteristics (relative to thermal) of the consolidation. They are evidenced by means of two types of tests (thermal consolidation and mechanical consolidation). The two types of tests lead to quantitative results comparable with regards to characteristic parameters of both types of consolidation. Some elements of interpretation are proposed to integrate all of the experimental results within a framework of thinking resorting to the thermoelastoplastic behaviour of the soil under study and to the thermal and mechanical hardening phenomena.Key words: unsaturated soils, consolidation, thermal, mechanical, coupling, hardening.
The thermal consolidation of unsaturated soils in a thermo-hydro-mechanical framework is studied in a thermal triaxial apparatus described in the paper. The results of the first tests performed, under a given state of stress, on both silty and clayey soils, show some similarities between purely thermal consolidation and mechanical consolidation on saturated soils. Key words: unsaturated soils, temperature, triaxial, consolidation. [Journal translation]
Transferts d’eau et transport de solutés dans les sols non saturés : solution analytique et développement numérique utilisant la méthode des lignes
