Post on 07-Jul-2015
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Geotechnical and environmental
considerations when redeveloping
deep-filled and former landfill sites
14 November 2014 1
Peter WitheringtonManaging Director
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Introduction
Significant constraints:
Social
Economic
Environmental
Engineering
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BRE 424 Charles and Watts
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The problem of deep fill
Received little research attention
“…the heterogeneous nature of many waste fills makes characterisation and
analysis difficult, and it is easy to understand why the attention of geotechnical
engineers has usually focussed on more promising and better behaved natural
soils…”
BRE reaction:
Monitoring of field performance
Characterising fills on the basis of observed performance
Assessing the effectiveness of various ground-treatment techniques
Dr J. A. Charles, 2008 Rankine Lecture, ‘The engineering behaviour of fill
materials: the use, misuse and disuse of case histories’
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Settlement mechanisms
Applied loading is rarely the problem…
However, we must address
Self weight
Change of groundwater level
Collapse settlement
Decomposition of biodegradable material
Chemical decomposition
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How to investigate properties
Conventional investigation is of little use.
Difficulty of
Drilling
Sampling
In situ testing
Laboratory testing
Need for
Long-term monitoring of
surface settlement
groundwater level
Large and medium-size loading tests
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Treatment methods
“With non-engineered fills the unexpected is only too likely to occur. Ground
treatment before construction can mitigate or forestall the effects of the
unexpected.”
Consider
Engineered backfilling
Dynamic compaction
Vibro compaction
Pre-loading (surcharging)
Pre-inundation
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Opportunity?
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Opportunity!
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Opportunity?
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Three centuries of mining
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Opportunity!
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Investigations: instrumentation
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Load tests
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Load tests
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Load tests
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And?
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