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Quests of waste mechanics

Mechanical properties of municipal solid waste

Technical University Braunschweig (Germany), 1990-1996
supported by Deutsche Forschungsgemeinschaft

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OBJECTIVES

     

  • Determination of mechanical properties of different types of municipal solid waste
  • Investigation of basic mechanisms, the mechanical behavior is due to
  • Identification of material parameter affecting the mechanical properties
  • Development of appropriate calculation methods

METHOD

     

  • Development of a new bearing model for MSW considering its ability to incorporate tensile forces backing the shear strength (so called fibres cohesion)
  • Design of a new testing device: the tension test under normal load
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Tension test under normal load: testing procedure
above: testing device after loading
below: testing device durcing tension test

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Left: Loading of MSW into
    testing box

 

Below: Transport to laboratory

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Waste sample after tension test: Cross-section through failure area. Fibres are still in contact, but tensile strength has been succeeded, yet.

RESULTS

     

  • Shear strength is dominated by fibers
  • The portion of shear strength due to fiber effects is called fibrous cohesion
  • Fibrous cohesion shows linear relation to normal stress (vertical to main fiber direction)
  • Shear strength of MSW can amount to normal stress (equvalent to phi = 45 degree!)
  • Fibrous cohesion can be implemented in analytical calculation methods
  • New calculation methods allow steeper slopes but also gives realistic limits for stability

 

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Approach for new calculation method: Goettingen-Deiderode, landfill mining project
Construction of a 75 degree steep slope ton save mining works (300.000 cubic meters)

REFERENCES

Koelsch(1995): Material values for some mechanical properties of domestic waste. CISA (eds.): Proceedings of the Fifth International Landfill Symposium, Vol. 2, Cagliari (Italy). Download

Koelsch, Ziehmann (2004): Landfill stability – risks and challenges. Waste Management World, issue Mai/June, ISWA, Copenhagen. Download

Several German publications available

Dr. Kölsch GmbH | office@dr-koelsch.de | mobil: +49 179 324 3108

 

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