A new laboratory apparatus for testing geomembrane leakage with mine tailings under large earth and fluid pressures

Prabeen Joshi, Richard W.I. Brachman, R. Kerry Rowe

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Geosynthetics

ABSTRACT: ratory apparatus for testing geomembrane leakage with mine tailings under large earth and fluid pressures Prabeen Joshi, Richard W.I. Brachman & R. Kerry Rowe GeoEngineering Centre at Queen'sŒRMC, Queen's University Kingston, Ontario, Canada ABSTRACT The design and development of a new high-pressure apparatus that is capable of simulating large effective stresses on a geomembrane liner is presented. The system is intended to be used for studying leakage from defects in geomembrane liners in large mine tailings application or dams. Results from a prototype test conducted on silty sand with a geomembrane with circular hole and finite element seepage analysis of the test is presented. Preliminary observations show that the apparatus is able to simulate the field conditions extremely well. RÉSUMÉ La conception et le développement d'un nouveau système d'application de haute pression pour simuler les grandes contraintes effectives subies par une géomembrane est présenté. Le système est destiné à être utilisé pour étudier les fuites liées à l'existence de défauts dans les géomembranes utilisées comme étanchéité dans les applications de stockage de résidus miniers de grande hauteur ou les barrages. Le résultat d'un essai de prototypage réalisé sur du sable limoneux avec une géomembrane présentant un défaut circulaire et une analyse par éléments finis de l'écoulement dans le test sont également présentés. Des observations préliminaires indiquent que le système est capable d'extrêmement bien simuler les conditions de terrain. 1 INTRODUCTION Geomembranes can be very effective at controlling leakage for environmental containment where the escape of fluid under a hydraulic gradient is limited to flow through holes in the geomembrane. In municipal solid waste (MSW) landfills, there is typically a very highly permeable material above the geomembrane as a drainage layer (which limits the head acting on the liner) and a very low permeability, k, material below the geomembrane (e.g., a geosynthetic clay liner or a compacted clay liner) to limit leakage through any holes in the geomembrane, Figure 1. Figure 1 Geomembrane hole in a typical municipal solid waste landfill configuration. Geomembranes have the potential to be used to greatly limit leakage of fluids from tailings storage facilities. Relative to MSW landfills, in many tailings containment applications (Figure 2): the vertical stress acting on the liner can be much higher (possibly affecting both k and interface transmissivity, ), the pore pressures acting on the liner can be much, much higher (with an increased hydraulic gradient and possible migration of fines with the high local seepage stresses), the hydraulic conductivity of the material above the geomembrane (i.e. tailings) is much lower (providing greater resistance to flow above the hole), and the hydraulic conductivity of the material below the geomembrane (i.e. engineered foundation layer) is not as low (providing less resistance to flow below the hole). However, the net effect of these differences on the resulting leakage for tailing applications is unknown. Measurements of leakage are required from experiments conducted under potentially high total stresses and high pore pressures. Figure 2 Geomembrane hole in a mine tailings containment configuration. The objective of this paper is to report on the development of a new laboratory apparatus for testing geomembrane leakage for mine tailing applications under large earth and fluid pressures. The boundary conditions of the apparatus and experimental procedures are described. Results from prototype test with silty sand High k drainage layer Hole Q hw Geomembrane Vertical Stress from Waste Low k liner Higher k underliner Tailings low k Hole Q =? Geomembrane Vertical Stress from Tailings High pore pressure

RÉSUMÉ: laboratory apparatus for testing geomembrane leakage with mine tailings under large earth and fluid pressures Prabeen Joshi, Richard W.I. Brachman & R. Kerry Rowe GeoEngineering Centre at Queen'sŒRMC, Queen's University Kingston, Ontario, Canada ABSTRACT The design and development of a new high-pressure apparatus that is capable of simulating large effective stresses on a geomembrane liner is presented. The system is intended to be used for studying leakage from defects in geomembrane liners in large mine tailings application or dams. Results from a prototype test conducted on silty sand with a geomembrane with circular hole and finite element seepage analysis of the test is presented. Preliminary observations show that the apparatus is able to simulate the field conditions extremely well. RÉSUMÉ La conception et le développement d'un nouveau système d'application de haute pression pour simuler les grandes contraintes effectives subies par une géomembrane est présenté. Le système est destiné à être utilisé pour étudier les fuites liées à l'existence de défauts dans les géomembranes utilisées comme étanchéité dans les applications de stockage de résidus miniers de grande hauteur ou les barrages. Le résultat d'un essai de prototypage réalisé sur du sable limoneux avec une géomembrane présentant un défaut circulaire et une analyse par éléments finis de l'écoulement dans le test sont également présentés. Des observations préliminaires indiquent que le système est capable d'extrêmement bien simuler les conditions de terrain. 1 INTRODUCTION Geomembranes can be very effective at controlling leakage for environmental containment where the escape of fluid under a hydraulic gradient is limited to flow through holes in the geomembrane. In municipal solid waste (MSW) landfills, there is typically a very highly permeable material above the geomembrane as a drainage layer

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Cite this article:
Prabeen Joshi; Richard W.I. Brachman; R. Kerry Rowe (2014) A new laboratory apparatus for testing geomembrane leakage with mine tailings under large earth and fluid pressures in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper313,author = Prabeen Joshi; Richard W.I. Brachman; R. Kerry Rowe,title = A new laboratory apparatus for testing geomembrane leakage with mine tailings under large earth and fluid pressures,year = 2014}