Comparative assessment of single and double interface shear strength properties: A case study of a landfill project in the Western Cape Province, South Africa

Abstract

Incorporation of multi-layered series of geosynthetics and geomaterials has presented new potential interfaces for shear failure of lining systems in engineered municipal solid waste (MSW) landfills. In the laboratory, interface shear strength parameters used in the design of lining systems especially side-slopes and bases are determined through single interface testing configuration according to ASTM D5321-20 and ASTM D6243-20 standards. This testing configuration, however, gives a limited understanding of shear strength transfers between the lining components when a multi-layered lining system has been proposed. Multi-interface testing configuration has been sought as an alternative by several scholars to address the above limitation. However, there is little information available as it is not stipulated in any official standard. This study was thus, conducted to ascertain the potential use of multi-interface testing methods through a case study of a proposed lining system for a new landfill cell in South Africa. It was found that single and multi-interface testing on specimens that involved geosynthetics only in the setup, similar results were observed. However, a dissimilarity in interface shear results was observed on those that involved geomaterials and geosynthetics.