Mechanical

Mechanical properties of municipal solid waste

Funding: German Research Foundation (DFG- Deutsche Forschungsgemeinschaft), 1990-1996

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
zugversuche müll
Photo credit: Tanja Borowiec/Alle Rechte bei der TU-Braunschweig
scherversuch müll
Photo credit: Tanja Borowiec/Alle Rechte bei der TU-Braunschweig

Testing procedur

zugversuch
Photo credit: Tanja Borowiec/Alle Rechte bei der TU-Braunschweig

Fig. 3: loading of MSW into testing box, transport to laboratory, running the teste

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
geotec
Photo credit: Tanja Borowiec/Alle Rechte bei der TU-Braunschweig

Fig. 4: Shear strength of municipal solid waste - bilinear failure criteria

References:

Kölsch, F. (1995): Zur Standsicherheitsberechnung von Abfalldeponien. Bauingenieur 70, 175-181,
Springer Verlag, Berlin

Kölsch, F. (1996): Der Einfluss der Faserbestandteile auf die Scherfestigkeit von Siedlungsabfall.
Mitteilungen des Leichtweiß-Instituts für Wasserbau, Technische Universität
Braunschweig, Heft 133