Investigating Shear Behaviour of Bituminous Geomembrane (BGM)-Overliner Interface in Heap Leach Applications

ABSTRACT: Bituminous Geomembranes (BGMs) are currently used in different mining applications including heap leach pads. These pads are typically constructed on slopes to allow the collection of the pregnant leach solution or constructed with slopes to minimize the footprint of the mining application. However, there is a paucity of research examining the shear properties of geomembrane-soil interface when considering BGM as the primary liner material. Thus, a Laboratory investigation is conducted using the large-scale Direct Shear Apparatus to study the interface shear strength mobilized between a BGM and a coarse-grained typically in contact with geomembrane liners in heap leach pads. A customized base plate is used with the apparatus for all the testing to avoid the slippage of the BGM during the interface tests. It is shown that with an increase in normal stress from 50 kPa to 1000 kPa, the observed interface shearing is a function of the BGM thickness, internal structure and the overliner characteristics. Additionally, the interface shear parameters obtained are compared to those obtained for the textured and smooth polyethylene geomembranes.