Thermal effects on mechanical behaviour of soil–structure interface

Abstract

8The mechanical behaviour of the soil-structure interface plays a major role in the shear 9 characteristics and bearing capacity of foundations. In thermo-active structures, due to 10 non-isothermal conditions, the interface behaviour becomes more complex. The objective 11 of this study is to investigate the effects of temperature variations on the mechanical 12 behaviour of soils and soil-structure interface. Constant normal load (CNL) and constant 13 normal stiffness (CNS) tests were performed on soil and soil-structure interface in a direct 14 shear device at temperatures of 5, 22 and 60 o C. Fontainebleau sand and kaolin clay were 15 used as proxies for sandy and clayey soils. The sandy soil was prepared in a dense state, 16 and the clayey soil was prepared in a normally consolidated state. The results showed 17 that the applied thermal variations have a negligible effect on the shear strength of the 18 sand and sand-structure interface under CNL and CNS conditions, and the soil and soil-19 structure interface behaviour could be considered thermally independent. In clay samples 20 the temperature increase, increased the cohesion and consequently the shear strength, 21 due to thermal contraction during heating. The temperature rise had less impact on the 22 shear strength in the case of the clay-structure interface than in the clay samples. The 23 adhesion of the clay-structure interface, is less than the cohesion of the clay samples. 24 Résumé 27 Le comportement mécanique de l'interface sol-structure est d'une grande importance en 28 1 raison du rôle de l'interface dans la résistance due au frottement et la capacité por-29 tante des structures. Dans les structures thermo-actives du fait de la variation de la 30 température, le comportement de l'interface devient plus complexe. L'objectif de ce tra-31 vail est d'étudier l'effet des variations de température sur le comportement mécanique 32 de l'interface sol-structure. Des essais avec des conditions de charge normale constante 33 (CNL) et de rigidité normale constante (CNS) ontété réalisées dans une boîte de cisaille-34 ment directà différentes températures, 5 o , 22 o et 60 o C sur deséprouvettes sol-sol et 35 sol-structure. Le sable de Fontainebleau et le kaolin ontété utilisés comme materiaux de 36 référence pour les sols sableux et argileux. Les résultats ont montré que les variations ther-37 miques appliquées ont un effet négligeable sur la résistance au cisaillement des interfaces 38 sable-sable et sable-structure dans les conditions CNL et CNS et que le comportement 39 du sable peutêtre considéré commeétant indépendent de la température. Dans l'argile 40é tudiée, l'augmentation de la température augmente la résistance au cisaillement en rai-41 son de la contraction thermique pendant le chauffage, ce qui augmente la cohésion du 42 sol. L'augmentation de température a eu moins d'impact sur la résistance au cisaillement 43 dans le cas de l'interface argile-structure que dans leséchantillons argile. L'adhésion de 44 l'interface argile-structure est infér...

Non-isothermal soil-structure interface model based on critical state theory

“…Thermally induced hardening of NC clay-concrete interface was found to be minor at a low normal stress (150 kPa), while it was significant at higher normal stresses (225 and 300 kPa). Among these studies, the experimental results of Maghsoodi et al (2020b) are presented in the following. Fig.…”

“…They concluded that the shear stress increase in the clay-structure interface could be due to thermally induced overconsolidation of normally consolidated clay. To support this statement, data from Maghsoodi et al (2020b) are provided. Fig.…”

Effect of Temperature on the Cyclic Behavior of Clay–Structure Interface

“…In such a setup, the temperature of the fully saturated shear box container can be controlled by three thermocouples, one in the lower half of the shear box, another on the upper half of the shear box and the last one in the container. The device can be programmed either in stress or deformation controlled tests (Maghsoodi et al 2019b). The lower half shear box is displaced horizontally to apply the shear.…”

“…Regarding the impact of temperature on the soil-structure interface, some experimental studies have been performed (Di Donna et al 2015;Yavari et al 2016;Li et al 2018;Maghsoodi et al 2019b;Yazdani et al 2019) In this context, this study was focused on the one-way cyclic behavior of clay-structure interface under isothermal or non-isothermal conditions. The effects of two parameters on strain accumulation, excess pore water pressure and cyclic degradation were more specifically considered.…”

Thermal effects on one-way cyclic behaviour of clay-structure interface

“…The number of cycles to failure increased for heated samples due to the densification of clay under drained heating and also the pore pressure of heated samples was slightly less than unheated ones. Regarding the impact of temperature on the soil-structure interface, some experimental studies have been performed [9,16,17] on direct shear device and concerning the in-situ behavior; [18] have developed a thermal borehole shear device to study effect of temperature on the in situ shear behavior of soil-concrete interfaces, but to the knowledge of the authors very few studies have been carried out on the thermal effects on the cyclic behavior of clay-structure interface. [9] performed cyclic constant normal stiffness (CNS) two-way strain controlled tests at different temperatures on illite clay.…”