Finite-Discrete Element Analysis of Interface Shear Damage to HDPE Geomembrane in Contact with Gravel Drainage Layer

Abstract

High density polyethylene (HDPE) geomembrane (GM) is usually used as a hydraulic barrier in waste containment applications including municipal solid waste facilities. Stress concentration resulting from direct contact with stones, gravel and other drainage material may cause significant damage to the GM sheet. Protection layers are generally used to keep the GM safe against puncture and tear. However, GM sheets are sometimes placed directly under crushed stones drainage layer containing relatively large size particles protruding from the surface. Under these conditions, interface shear displacement may develop within the liner system causing damage to the GM material. In this study a coupled finite-discrete framework has been developed to investigate the behaviour of a gravel drainage layer located above HDPE geomembrane sheet and subject to moderate to high normal stress conditions. The geomembrane is modelled using finite elements (FE) whereas the drainage layer and the underlying foundation are modelled using discrete elements (DE). Numerical simulation is performed based existing experimental results for the same configuration and detailed behaviour of the GM sheet is then investigated. Results show that shear displacement developing between the drainage layer and the HDPE geomembrane should be considered in the design of landfill barrier system.