Evaluating Interface Properties and Predicting Landfill Liner Stability Under Static and Seismic Loading
Predicting landfill stability and maintaining stable configuration during filling is responsibility of engineers. Majority of failures occurs within waste mass and along landfill liners. This paper will discuss the methods adopted to predict landfill liner stability in terms of interface performances. Interfaces shear strength parameter evaluation for landfill liner systems have been a tedious testing process. Various testing methods and guidelines have been proposed by engineers and researchers over the years. The current testing procedures are based on ASTM testing guideline and basic fundamental engineering testing philosophies. Hence there is a need for much ideal testing equipment which can perform the entire test series required for landfill liner parameter evaluations. The equipment are required to perform interface test between:
- soil and soil (GCLs)
- geomembrane (HDPEs and PVC) and soil
- geosynthetic (GCLs) / compacted (CCLs) clay liners and soil
- geomembrane and geotextile
- geotextile and soil
- geotextile and geosynthetic (GCLs) / compacted (CCLs) clay liners
- geomembrane and geosynthetic (GCLs) / compacted (CCLs) clay liners.
Having such variety in requirement and testing complexity for landfill liner system, this paper also addresses the modification adapted to a large scale shear box in order to perform the above said interface tests. The modified large scale shear box is used to study interface performance of various combination of liners. Test data are compiled into landfill models to study the stability performance of landfill liners under static and seismic loading. Finding from the analysis are compiled further to evaluate interface factor of safety prediction methodology for landfill liners. The liner interface parameter data together with factor of safety prediction methodology presented herewith will be a quick reference guide for engineers. Details of laboratory test and analysis results will be presented here with.
The world consumption of natural resources has been increasing exponentially. In Japan the consumption of resource is at 1900 million tones annually. This consumption generates waste of
600 million tones, which consist of 400 million tons of industrial waste and 50 million tons of municipal waste. Out of this 220 million tons are recycled and reused, 324 million tons are pre-treated waste for disposal. 56 million tons are disposed to landfill in Japan in year 2000. The estimated life spend of landfill site in Japan is about 6 to 7 years of operational. It becomes very difficult to build new sites in Japan cause of the syndrome of “Not In My Back Yard”.
The cost of a new site in Tokyo could cost up to 500 million US dollars. The running cost of existing landfill site in Tokyo is at 300 USD / m3. A landfill also behaves as in-situ bioreactor, where the contents undergo complex biochemical reactions. The adoption of suitable design and construction methods are essential not only to reduce design and construction cost, but also to minimize long term operation, maintenance and monitoring cost.
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