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Mechanical behaviour of the soil-structure interface plays a major role in the shear characteristics and bearing capacity of foundations. In thermoactive structures, due to nonisothermal conditions, the interface behaviour becomes more complex. The objective of this study is to investigate the effects of temperature variations on the mechanical behaviour of soils and the soil-structure interface. Constant normal load (CNL) and constant normal stiffness (CNS) tests were performed on the soil and soil-structure interface in a direct shear device at temperatures of 5, 22, and 60[degrees]C. Fontainebleau sand and kaolin clay were used as proxies for sandy and clayey soils. The sandy soil was prepared in a dense state and the clayey soil was prepared in a normally consolidated state. Results show that the applied thermal variations have a negligible effect on the shear strength of the sand and sand-structure interface under CNL and CNS conditions, and the soil and soil-structure interface behaviour could be considered thermally independent. In clay samples, an increase in the temperature increased the cohesion and consequently the shear strength, due to thermal contraction during heating. The temperature rise had less impact on the shear strength in the case of the clay-structure interface than in the clay samples. The adhesion of the clay-structure interface is less than the cohesion of the clay samples. Key words: shear strength, constant normal stiffness (CNS), soil-structure interface, temperature, thermo-active structures. Le comportement mecanique de l'interface sol-structure joue un role important dans les caracteristiques de cisaillement et la capacite portante des fondations. Dans les structures thermoactives du fait de la variation de la temperature le comportement de l'interface devient plus complexe. L'objectif de cette etude est d'etudier les effets des variations de temperature sur le comportement mecanique des sols et l'interface sol-structure. Des essais avec des conditions de charge normale constante (CNL) et de rigidite normale constante (CNS) ont ete realises dans une boite de cisaillement direct a differentes temperatures, 5, 22 et 60[degrees]C sur des eprouvettes sol-sol et sol-structure. Le sable de Fontainebleau et le kaolin ont ete utilises comme substituts des sols sableux et argileux. Le sol sableux a ete prepare dans un etat dense et le sol argileux dans un etat normalement consolide. Les resultats montrent que les variations thermiques appliquees ont un effet negligeable sur la resistance au cisaillement du sable et de l'interface sable-structure dans les conditions de CNL et CNS, et que le comportement du soil et de l'interface sol-structure pourrait etre considere comme etant independant de la temperature. Dans les echantillons d'argile, l'augmentation de la temperature augmente la cohesion et, par consequent, la resistance au cisaillement, en raison de la contraction thermique pendant le chauffage. L'augmentation de la temperature a eu moins d'impact sur la resistance au cisaillement dans le cas de l'interface argile-structure que dans les echantillons d'argile. L'adhesion de l'interface argilestructure est inferieure a la cohesion des echantillons d'argile. Mots-cles : resistance au cisaillement, rigidite normale constante (CNS), interface sol-structure, temperature, structures thermoactives., Introduction The bearing capacity of foundations is highly dependent on the mechanical behaviour of the soil-structure interface. Therefore, the soil-structure interactions at the interface are of primary importance in foundation [...]

The shrinkage and swelling of clayey soils is a natural hazard, which may significantly affect buildings. Foundation settlement caused by this geohazard for buildings constructed on expansive soils undergoing a drought period was studied. A soil-structure interaction model is proposed. The hydromechanical coupling is taken into account by using the state surface approach. Settlement is evaluated according to building stiffness, ground hydromechanical properties, surface suction variation, suction profile, and foundation depth. The uncertainties are considered by using the Monte Carlo approach, and an application has been performed for the average settlement assessment of a group of buildings. This paper outlines the significant dependency of the final settlement on the building stiffness. It highlights the benefits of rigid buildings and deeper foundations to reduce vulnerability to this geohazard. Key words: shrinkage-swelling, soil-structure interaction, foundation, building stiffness. Le retrait gonflement de sols argileux est un alea naturel qui peut provoquer des dommages importants aux batiments. Le tassement des fondations, provoque par cet alea a ete etudie, pour des maisons construites sur des sols gonflants subissant une variation hydrique lors d'une periode de secheresse. Un modele d'interaction sol-structure est propose. Le couplage hydromecanique est pris en compte grace au concept de surface d'etat. Le tassement est evalue en fonction de la rigidite du bati, des proprietes hydromecaniques du sol, de la variation de succion en surface, du profil de succion et de la profondeur de fondation. Les incertitudes sont considerees en utilisant une approche de type Monte Carlo et une application est realisee afin d'evaluer le tassement moyen d'un ensemble de batiments. Les resultats montrent l'influence de la rigidite du bati sur le tassement final. Ils mettent en evidence l'interet de la rigidite du bati et de la profondeur d'assise des fondations pour reduire la vulnerabilite vis-a-vis de cet alea. Mots-cles : retrait-gonflement, interaction sol-structure, fondation, rigidite du batiment., Introduction Shrinkage and swelling of clayey soils is an important geo-hazard all over the world. The study of its impacts on buildings for risk management raises many questions because of [...]