Interface Shear: The Significance in Geotechnical Structures

Author(s): 
Graham Howell, Anton Kirsten
Date: 
Thursday, May 5, 2016
First presented: 
First South African Geotechnical Conference
Type: 
Published paper
Category: 
Geotechnical

It is well known that low strength natural materials under foundations and in slopes can cause bearing capacity and slope failures. With the increased use of manufactured materials such as HDPE liners and geotextiles, similar conditions can inadvertently be built into the structure. These interface shear aspects occur between liner and geotextile, liner and soil, geotextile and soil and even within the confines of the geotextile. Injudicious use of low interface shear materials can lead to excessive deformation and even catastrophic failure. The many potential interface shear planes that can exist in geotechnical structures are considered with reference to 20 years of published research and actual recent shear box tests carried out for validation purposes for lined structures. The paper further considers a simplistic calculation method using block limit equilibrium and finite element simulations to understand the problems that exist in these structures. The concept of ‘excess shear’ which leads to overstressing of liners is also discussed.

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