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|Title: ||Analysis of steep sided landfill lining systems|
|Authors: ||Fowmes, Gary John|
|Keywords: ||Landfill engineering|
Steep sided lining systems
Steepwall lining systems
Geosynthetics, waste barrier interaction
Interface shear strength variability
Reliability based design
Randomly reinforced soil
|Issue Date: ||2007|
|Publisher: ||© Gary John Fowmes|
|Abstract: ||The EC Landfill Directive (1999), which is enforced in England and Wales through
the Landfill (England and Wales) Regulations (2002), has increased the technical
challenge associated with the design and construction of landfill containment systems,
in particular those on steep side slopes. Increased numbers of lining system
components, varied configurations, and complex loading scenarios require advanced
analysis tools to facilitate design.
This project involved the development of advanced numerical modelling techniques,
based on the FLAC finite difference modelling code. The analysis toolbox can be
used to predict the behaviour of multilayered geosynthetic and soil lining systems,
during and after staged construction. The model can include non-linear interface and
geosynthetic axial properties, represent complex loading, including downdrag from
the waste mass, whilst retaining the flexibility to represent varied geometries and
include engineered support structures.
Whilst numerical modelling is becoming increasingly commonplace in commercial
design, there is little evidence of the validation of numerical models with field or
experimental data. Validation of the analysis toolbox described in this document was
conducted by back analysis of published data, modelling of landfill failure
mechanisms, and comparisons to large scale laboratory testing. Design of field scale
instrumentation has also been carried out as part of this project.
The influence of interface shear strength variability has been assessed through the
compilation of a comprehensive database, and the effect of this variability on lining
system behaviour assessed through reliability based analyses. This has shown
probability of failures may be higher than proposed limiting values when adopting
traditional accepted factors of safety.
A key area of interest identified during the project was the requirement for support,
potentially through reinforcement, of the geological barrier. The inclusion of
randomly reinforced fibres in bentonite enhanced soil has shown the potential for
increased strength, without adverse effects on hydraulic barrier performance.
Additionally, the influence of geomembrane seams on lining system integrity has
been investigated, showing that fusion welded seams can result in stress concentration
and extruded seams can cause significant stress concentration.|
|Description: ||A dissertation thesis submitted in partial fulfilment of the requirements for the award of the Engineering Doctorate (EngD) degree at Loughborough University.|
|Appears in Collections:||EngD Theses (CICE)|
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