Éléments de couplage thermomécanique dans la consolidation de sols non saturés

Abstract

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.

A New Isotropic Cell for Studying the Thermo-Mechanical Behavior of Unsaturated Expansive Clays

“…Other works on unsaturated silty sand performed by Recordon (1993) and Saix et al (2000) showed also this independence. The decrease of the preconsolidation pressure with temperature increase is also consistent with the results of Sultan et al (2002) on saturated Boom clay and that of Romero et al (2003) on unsaturated compacted Boom clay.…”

“…The triaxial apparatus developed by Saix and Jouanna (1990) allowed the control of capillary suction from 0 to 100 kPa and a control of temperature from 25 °C to 80 °C. This apparatus was used to study the thermo-mechanical behavior of unsaturated silty sand (Saix 1991, Saix et al 2000, Jamin et al 2003. The axis translation technique was used to control the soil suction in oedometer (Romero et al 1995) and in triaxial apparatus (Romero et al 1997) under temperatures varying from 22 °C to 80 °C.…”

Thermo-mechanical behaviour of a compacted swelling clay

“…For unsaturated soils, Recordon (1993) and Saix et al (2000) observed the temperature independence of λ(s) and κ for sand and silty clayey sand. On the contrary, Romero et al (2003) observed a temperature insensitivity of κ but a temperature dependence of λ(s) for compacted Boom clay.…”

“…The same phenomena have been observed by Romero et al (2003) , PI = 27%), also in an oedometer. Saix et al (2000) performed compression tests in a triaxial cell at constant suction (4.9 kPa) and temperature (30 -70°C) on a clayey silty sand ( % 25 = L w , PI = 10.5%). A decrease followed by an increase of p 0 with increasing temperature was observed, the minimum value corresponding to a temperature of 45 °C.…”

Thermo-mechanical Behaviour of a Soil. Yield Surface Evolution

“…In the non-isothermal unsaturated case, Saix et al [7] have studied experimentally the effect of a thermal hardening in elastic limits in vertical total stress for a given suction. Jamin et al [8] were interested more particularly in the determination, for various temperature, of a yield surface f (p, q, s) = 0, where p is the net mean stress, q the deviatoric stress and s the suction.…”