Overview of the evolution, performance and state of a bentonite-based tunnel seal after 5 years of operation

Dixon, David A.; Martino, J.B.; Vignal, B.; Masumoto, Kazuhiko; Fujita, T.

doi:10.1016/j.pce.2006.03.006

Cited by 7 publications

(2 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The solid unit weight of the sand/bentonite mixture is 2.67 Mg/m 3 . The mixture used in this work is similar to that used in the full-scale "Tunnel Sealing Experiment" (TSX test) conducted in Canada (Martino et al 2007;Dixon et al 2007).…”

Section: Methodsmentioning

confidence: 99%

Determining the unsaturated hydraulic conductivity of a compacted sand–bentonite mixture under constant-volume and free-swell conditions

Cui¹,

Tang²,

Loiseau³

et al. 2008

Physics and Chemistry of the Earth, Parts A/B/C

173

View full text Add to dashboard Cite

Highly compacted sand-bentonite mixtures are often considered as possible engineered barriers in deep high-level radioactive waste disposals. In-situ, the saturation of these barriers from their initially unsaturated state is a complex hydro-mechanical coupled process in which temperature effects also play a role. The key parameter of this process is the unsaturated hydraulic conductivity of the barrier. In this paper, isothermal infiltration experiments were conducted to determine the unsaturated hydraulic conductivity according to the instantaneous profile method. To do so, total suction changes were monitored at different locations along the soil specimen by using resistivity relative humidity probes. Three constant volume infiltration tests were conducted showing, unexpectedly, a decrease of the hydraulic conductivity during infiltration. One test performed under free-swell conditions showed the opposite and standard trend. These observations were interpreted in terms of microstructure changes during wetting, both under constant volume and free swell conditions.

show abstract

Section: Methodsmentioning

confidence: 99%

Determining the unsaturated hydraulic conductivity of a compacted sand–bentonite mixture under constant-volume and free-swell conditions

Cui¹,

Tang²,

Loiseau³

et al. 2008

Physics and Chemistry of the Earth, Parts A/B/C

173

View full text Add to dashboard Cite

show abstract

“…In the Canadian Underground Research Laboratory, a bentonite-based tunnel sealing experiment (TSX) was conducted between 1998 and 2004 in an intact volume of rock within a granitic pluton. Dixon et al (2007) reported on the evolution of two bulkheads, one of which consisted of highperformance concrete and the other of blocks of compacted sand-bentonite material. The TSX was installed in a 3.5 m high by 4.25 m wide tunnel located 420 m below the surface.…”

Section: Real-scale Studiesmentioning

confidence: 99%

Mineralogical investigations of the first package of the alternative buffer material test – II. Exchangeable cation population rearrangement

Dohrmann¹,

Olsson²,

Kaufhold³

et al. 2013

Clay miner.

View full text Add to dashboard Cite

AB ST R ACT : Bentonites are candidate materials for the encapsulation of radioactive waste. In the 'Alternative Buffer Material test' (ABM), compacted ring-shaped blocks of eleven different buffer materials (mainly bentonites) were packed vertically on top of each other with an iron tube as heater in the centre. These buffer materials started with various exchangeable cation populations (EC population ). The first 'ABM package' was terminated 28 months after installation and the bentonites had been exposed to the maximum temperature (130ºC) for about one year. The aim of the present study is first: to describe modification of the cation exchange population, and second to understand the influence of the groundwater on cation exchange at different scales. No significant horizontal variation of any exchangeable cation (EC) was detected between 1 and 7 cm distance from contact with the iron tube. Large total differences of the EC populations , however, were observed for the individual blocks after the field experiment (n = 21 blocks) with respect to the composition of the reference materials. The average cation exchange capacity (CEC) values of the analysed bentonites (n = 9 blocks) decreased by 5.5 meq/100 (1.1À8.8 meq/100 g) after the experiment. Exchangeable Na + and Mg 2+ decreased on average, whereas Ca 2+ increased. This trend was pronounced in the top region of the parcel (upper seven blocks). Although most changes occurred on the large scale of the whole test parcel, small but important changes were also recorded in the vertical direction on the centimetre scale. The observed differences cannot be explained assuming simply that a bentonite reacts only with neighbouring blocks, which would mean that the system was more or less closed. The differences are much larger and the only conclusion from this observation is that the whole package seems to be influenced by the groundwater which was added from a water tank at the experiment site, enabling at least partial equilibration between the different blocks.

show abstract

Assessment of lacustrine/fluvial clays as liners for waste disposal (Lake Van Basin, Turkey)

Ateş

Yakupoğlu

2011

Environ Earth Sci

View full text Add to dashboard Cite

Overview of the evolution, performance and state of a bentonite-based tunnel seal after 5 years of operation

Cited by 7 publications

References 1 publication

Determining the unsaturated hydraulic conductivity of a compacted sand–bentonite mixture under constant-volume and free-swell conditions

Determining the unsaturated hydraulic conductivity of a compacted sand–bentonite mixture under constant-volume and free-swell conditions

Mineralogical investigations of the first package of the alternative buffer material test – II. Exchangeable cation population rearrangement

Assessment of lacustrine/fluvial clays as liners for waste disposal (Lake Van Basin, Turkey)

Contact Info

Product

Resources

About