Title

Effect of viscoelasticity on soil-geomembrane contact surfaces

Date of Award

2013

Degree Name

M.S. in Civil Engineering

Department

Department of Civil and Environmental Engineering and Engineering Mechanics

Advisor/Chair

Advisor: Ömer Bilgin

Abstract

Geosynthetics are widely used in geotechnical engineering projects. For instance, Geomembranes are one of the most commonly used geosynthetic type and they are used to provide impervious boundary. Geomembranes are usually made from high-density polyethylene (HDPE). When geomembranes are installed on sloping grounds, the soil geomembrane interface usually forms the critical planes due to low shear strength at the soil and geomembrane interface. In addition, HDPE is a viscoelastic material and has time-dependent properties. Under the constant applied stress, geomembrane made out of HDPE exhibit creep behavior and the strains increase with time. On the other hand, when a constant strain is applied, the material exhibit stress relaxation behavior and the stresses decrease with time. Taking into consideration this viscoelastic behavior, under a constant overburden soil load, the soil particles will continue to penetrate into the geomembrane that they are in contact with. These increase penetrations will increase the contact areas at the soil-geomembrane interface. It is expected that this would increase the interface shear strength, resulting in increased factor of safety for sliding. Therefore, it is important to characterize the change of soil-geomembrane contact areas with time. This would allow to model interface shear strength for various conditions. This thesis presents an experimental study conducted to model the change of soil-geomembrane interface contact areas with time.

Keywords

Geomembranes Viscosity, Geomembranes Elastic properties, Slopes (Soil mechanics) Stability, Shear strength of soils, Civil engineering; viscoelasticity; geomembrane; area-change; friction; shear; adhesion

Rights Statement

Copyright 2013, author

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