Evaluation of the influence of boundary confinement on the behaviour of unsaturated swelling clay soils

Siemens, Greg; Blatz, James

doi:10.1139/t08-125

Cited by 32 publications

(14 citation statements)

References 18 publications

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“…This is consistent with the conclusion of Villar et al (2008) and Siemens et al (2009) who found a similar relationship between swelling strain and swelling pressure. It can be seen that the final state of specimen governed the swelling pressure: for the samples with the same initial state, different pre-swelling strains led to different final dry densities and thus resulted in different swelling pressure.…”

Section: Discussionsupporting

confidence: 93%

Experimental study on the swelling behaviour of bentonite/claystone mixture

Wang

Tang

Cui

et al. 2012

Engineering Geology

197

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A mixture of the MX80 bentonite and the Callovo-Oxfordian (COx) claystone were investigated by carrying out a series of experiments including determination of the swelling pressure of compacted samples by constant-volume method, pre-swell method, zero-swell method and swell-consolidation method. Distilled water, synthetic water and humidity controlled vapour were employed for hydration. Results show that upon wetting the swelling pressure increases with decreasing suction; however, there are no obvious effects of synthetic water chemistry and hydration procedure on the swelling behaviour in both short and long terms. For the same initial dry density, the swelling pressure decreases with increasing pre-swell strain; whereas there is a well defined logarithmic relation between the swelling pressure and final dry density of the sample regardless of the initial dry densities and the experimental methods. It was also found that swelling pressure depends on the loading-wetting conditions as a consequence of the different microstructure changes occurred in different conditions. Furthermore, it was attempted to elaborate a general relationship between the swelling pressure and the final dry density for various reference bentonites.

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Section: Discussionsupporting

confidence: 93%

Experimental study on the swelling behaviour of bentonite/claystone mixture

Wang

Tang

Cui

et al. 2012

Engineering Geology

197

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“…Single porosity models are not able to tackle properly the role that different pore levels play during the hydration process of swelling clays. A more detailed analysis of the clay fabric effects in the evolution of the mock‐up test has therefore been performed with the aid of a double structure model 13–15. Using this concept, the effect of two dominant pore levels that typically exist in compacted expansive clays can be explicitly included in the analysis.…”

Section: Introductionmentioning

confidence: 99%

THM analysis of a large‐scale heating test incorporating material fabric changes

Sánchez

Gens

Olivella

2011

Num Anal Meth Geomechanics

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Engineered barriers are basic elements in the design of repositories for the isolation of high-level radioactive waste. This paper presents the thermo-hydro-mechanical (THM) analysis of a clay barrier subjected to heating and hydration. The study focuses on an ongoing large-scale heating test, at almost full scale, which is being carried out at the CIEMAT laboratory under well-controlled boundary conditions. The test is intensely instrumented and it has provided the opportunity to study in detail the evolution of the main THM variables over a long period of time. Comprehensive laboratory tests carried out in the context of the FEBEX and NF-PRO projects have allowed the identification of the model parameters to describe the THM behaviour of the compacted expansive clay. A conventional THM approach that assumes the swelling clay as a single porosity medium has been initially adopted to analyse the evolution of the test. The model was able to predict correctly the global THM behaviour of the clay barrier in the short term (i.e. for times shorter than three years), but some model limitations were detected concerning the prediction of the long-term hydration rate. An additional analysis of the test has been carried out using a double structure model to describe the actual behaviour of expansive clays. The double structure model explicitly considers the two dominant pore levels that actually exist in the FEBEX bentonite and it is able to account for the evolution of the material fabric. The simulation of the experiment using this enhanced model provides a more satisfactory reproduction of the long-term experimental results. It also contributes to a better understanding of the observed test behaviour and it provides a physically based explanation for the very slow hydration of the barrier.

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“…This line is useful in evaluating the equilibrium stresses developed in a sample for any given void ratio when inundated under constant volume conditions. The SCEL is similar in concept to the swell equilibrium limit (SEL) proposed by Siemens andBaltz (2009) andLiu et al (2014) for samples that experienced swelling under different vertical boundary conditions. Plots for the evolution of vertical stress with time due to sample inundation under different vertical stresses on the loading curve are shown in Fig.…”

Section: Resultsmentioning

confidence: 76%