On rapporte ici les resultats d'essais de gonflement sous confinement, d'essais de consolidation et de conductivite hydraulique effectues sur une membrane argile-geosynthetique (MAG) aiguilletee. On a examine les effets du liquide de percolation (eau distillee, solutions aqueuses salines avec des concentrations en NaCl de 0,01 et 2,0 M, lixiviat synthetique de type dechets municipaux), ainsi que les effets de la contrainte statique, du liquide hydratant et du degre d'hydratation de la bentonite a l'instant de l'application de la pression de confinement. L'augmentation de la concentration en sel de la solution et la diminution de la pression de confinement ont entraine une augmentation de la conductivite hydraulique. On a aussi montre que des concentrations en sel elevees dans le liquide hydratant augmentent la conductivite hydraulique. Les MAG soumises a des solutions de NaCl a des concentrations de 0,6 et 2,0 M etaient plus permeables que les MAG initialement hydratees a l'eau. Le liquide hydratant n'etait pas un facteur aussi critique pour des circulations de fluide a 0,1 M NaCl. On a egalement constate l'importance du degre d'hydratation de la bentonite lors de l'application de la pression de confinement, ce qui souligne les avantages hydrauliques qu'il y a a maximiser la contrainte verticale avant l'hydratation de la membrane. Les essais effectues avec le lixiviat synthetique ont donne des resultats comparables a ceux obtenus avec les solutions salines entre 0,2 et 0,8 M NaCl. On discute finalement les consequences pratiques de ces essais.

Geosynthetic clay liner (GCL) : chemical compatibility by hydraulic conductivity testing and factors impacting its performance

Natural Ca-montmorillonite clay soils or engineered clay barriers in western Canada are often used to contain brine generated from the surface disposal of potash tailings or from drilling activitie...

A review of the influence of clay–brine interactions on the geotechnical properties of Ca-montmorillonitic clayey soils from western Canada

The results of laboratory and in situ permeability tests can be used to predict the total leakage rate of a soilbentonite or clay liner. This prediction, however, ignores the large influence that ...

The 2000 R.M. Hardy Lecture: Full-scale hydraulic performance of soilbentonite and compacted clay liners

A sand–bentonite mix was used to form the liner of four lagoons for the La Tuque and Haute-Mauricie sewage water treatment project. This paper describes the site conditions, design, and constructio...

Design, construction, performance, and repair of the soil–bentonite liners of two lagoons

Compacted clay soils are used as barriers in geoenvironmental engineering applications and are likely to be exposed to salinization and desalinization cycles during life of the facility. Changes in pore fluid composition from salinization and desalinization cycles induce osmotic suction gradients between soil–water and reservoir (example, landfill/brine pond) solution. Dissipation of osmotic suction gradients may induce osmotic swelling and consolidation strains. This paper examines the osmotic swelling and consolidation behaviour of compacted clays exposed to salinization and desalinization cycles at consolidation pressure of 200 kPa in oedometer assemblies. During salinization cycle, sodium ions of reservoir fluid replaced the divalent exchangeable cations. The osmotic swelling strain developed during first desalinization cycle was 29-fold higher than matric suction induced swelling strain of the compacted specimen. Further, the diffusion controlled osmotic swelling strain was 100-fold slower than matric suction-driven swelling process. After establishment of ion-exchange equilibrium, saturated saline specimens develop reversible osmotic swelling strains on exposure to desalinization cycles. Likewise the saturated desalinated specimen develops reversible osmotic consolidation strains on exposure to cycles of salinization. Variations in compaction dry density has a bearing on the osmotic swelling and consolidation strains, while, compaction water content had no bearing on the osmotic volumetric strains.

Osmotic Swelling and Osmotic Consolidation Behaviour of Compacted Expansive Clay

The containment of brine in shallow ponds is one of the most serious problems facing waste-management engineers today. Brine waste is produced in many mining and processing operations. It is characterized by high salt concentrations which may seriously contaminate groundwater if not successfully contained. However, brine reacts chemically with clays used in liner construction. As brine permeates the liner, physicochemical interactions between the clay and brine lead to a reduction in volume of the liner. This shrinkage may cause cracking of the liner and the creation of a highly fractured permeable macrostructure.Numerous techniques have been tried to find an effective and economical method of containing brine. Some of these techniques have involved the use of soil, concrete, asphalt, and synthetic liners. However, all of these techniques have major deficiencies in either cost or effectiveness. This paper presents a case study of the first attempt to solve the volume change problem by designing and constr...

S. L. Barbour

Papers

Design and construction of a prehydrated sand-bentonite liner to contain brine