Thermal expansion and pore pressure generation in oil sands

Agar, J. G.; Morgenstern, N. R.; Scott, J. D.

doi:10.1139/t86-046

Cited by 60 publications

(34 citation statements)

References 7 publications

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“…After this peak heave, the pile settled gradually by 0·2% D. The same phenomenon was also observed by Ng et al (2015) and can be explained by the thermal-induced contraction of sand when heated (Kosar, 1983;Agar et al, 1986). Figure 2 shows that even though the temperature of EP-R remained almost constant, the temperature of sand surrounding the pile did not.…”

Section: Pile Head Displacementsupporting

confidence: 62%

“…Under a constant working load, the pile embedded in saturated Toyoura sand initially heaved when heated, but gradually settled when elevated temperature was maintained. This settlement was likely caused by thermal-induced contraction of sand (Kosar, 1983;Agar et al, 1986). Pasten & Santamarina (2014) simulated energy piles subjected to thermal cycles using the one-dimensional pile-soil load-transfer method (Poulos & Davis, 1980) modified to take into account the axial elongation/ shortening of the energy pile.…”

Section: Introductionmentioning

confidence: 99%

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Centrifuge modelling of displacement and replacement energy piles constructed in saturated sand: a comparative study

Gunawan

Shi

et al. 2016

Géotechnique Letters

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Energy piles serve as supporting structures and heat-exchange elements. They can provide thermal comfort much more efficiently than traditional air-sourced systems as the ground offers high thermal conductivity and a stable temperature below a certain depth. Energy piles are commonly installed as bored piles (replacement); however, driven (displacement) energy piles are also used in practice. A direct comparison of the performance of these two different types of energy piles subjected to thermal cycles is rarely explored not fully understood. In this study, two centrifuge energy model piles, one wished-in-place at one gravity (i.e. at low stress, simulating bored pile) and the other pile was jacked in at elevated gravity were constructed in saturated Toyoura sand. After construction, they were subjected to five heating and cooling cycles (7-37°C) under a constant working load. Cumulative settlement with a ratcheting pattern was observed for the 'bored' energy pile after five thermal cycles. In contrast, a slight heave was recorded for the jacked-in energy pile. The observed heave can be attributed to the densification effect and particle crushing of soil when the pile was jacked in, reducing or even eliminating thermal-induced contraction of sand and hence decreasing the reduction of horizontal stress during thermal cycles.

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Section: Pile Head Displacementsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Centrifuge modelling of displacement and replacement energy piles constructed in saturated sand: a comparative study

Gunawan

Shi

et al. 2016

Géotechnique Letters

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“…There are a number of experimental studies concerning thermal effects on saturated soils, see for instance [29][30][31][32]. Recent work in this area has been described in [33,34] Based on these results Hueckel and co-workers have pioneered the development of a thermo-plastic constitutive model for saturated soils.…”

Section: Thermo-plastic Model For Unsaturated Sollsmentioning

confidence: 99%

Constitutive Laws

Gens

1995

Modern Issues in Non-Saturated Soils

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Constitutive laws for unsaturated soils under nonisothermal conditions are presented in this Chapter. The development of the models is carried out in a progressive manner. First the Cam-clay constitutive law for saturated soils is briefly described. Using net stress and suction as independent stress variables, the Cam-clay model is generalized to include the effect of partial saturation. Some consequences of the model are reviewed and its prediction capabilities are tested in relation to some selected experimental results. Finally, the model is extended to include temperature effects. A suite of constiturive laws is therefore obtained capable of reproducing increasingly complex features of soil behaviour. Important advantages ensue from the fact that they can be regarded as progressive developments within a shared strain-hardening elasto-plastic framework.

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“…Thermal failure in sands was observed by Agar et al (1986) and suggested as a possible failure mechanism in ocean-floor sediments by Davis and Banerjee (1980).…”

Section: Introductionmentioning

confidence: 90%

Effective stress and water pressure in saturated clays during heating–cooling cycles

Hueckel¹,

Pellegrini²

1992

Can. Geotech. J.

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Experiments with heating and cooling cycles in undrained constant total stress conditions in triaxial apparatus are presented. Heating induces a large pore-water pressure increase, which eventually leads to a large irreversible strain and possible mechanical failure. Subsequent cooling produces a drop in water pressure. In one test the drop during cooling was more than two times higher than the previous increase during heating, reaching values of up to 2.30 MPa. An analysis of these findings in terms of a thermoplastic model is presented. The interpretation of these tests relies heavily on the kind of stress-partitioning hypothesis that is used. It was found that the described phenomena can be quantitatively dealt with using the classical effective stress principle, if the shear strength and consolidation are described in terms of temperature-dependent plastic yield limit.Des expkriences avec des cycles de chauffage et de refroidissement produits dans l'appareil triaxial dans des conditions non drainkes en contrainte totale constante sont presentees. Le chauffage induit une augmentation importante de la pression interstitielle qui conduit kventuellement a une grande deformation irrkversible et possiblement a une rupture mkcanique. Le refroidissement subskquent produit une chute dans la pression interstitielle. Dans un essai, la chute durant le refroidissement ktait plus de deux fois plus importante que l'accroissement anterieur durant le chauffage, atteignant des valeurs jusqu'a 2,30 MPa. L'on prksente une analyse de ces rksultats en fonction d'un modkle thermoplastique. L'interpretation de ces essais dkpend fortement de l'hypothkse de partition de contrainte utilisee. L'on a trouvk que, si la resistance au cisaillement et la consolidation sont dkcrites en fonction de la limite de deformation plastique dkpendante de la tempkrature, les phenomknes decrits peuvent &tre traitks quantitativement en utilisant le principe des contraintes effectives classique. IntroductionThis paper deals with cycles of heating and cooling of clay in undrained conditions. It is a continuation of previous work which focused on the response of clay mass to monotonic heating. Constant total stress undrained heatingcooling tests on saturated clays published previously are analysed. This sort of cyclic testing simulates thermomechanical behavior of clay around a heat source like a nuclearwaste repository. Nuclear waste has a decaying heat output. This leads to an initial increase of temperature in the soil mass after installation, followed by its gradual decrease (see,

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Thermal expansion and pore pressure generation in oil sands

Cited by 60 publications

References 7 publications

Centrifuge modelling of displacement and replacement energy piles constructed in saturated sand: a comparative study

Centrifuge modelling of displacement and replacement energy piles constructed in saturated sand: a comparative study

Constitutive Laws

Effective stress and water pressure in saturated clays during heating–cooling cycles

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