Vertical expanding of landfill with considering its component

Shear strength of landfill municipal solid waste (MSW) is a more important topic in landfill stability investigation. Impressibility of this material from the temperature and humidity regarding to its early component cause that this material suffering much change in its shape. This variation with filling condition such as prime compression and soil increasing for daily and monthly cover change structure of MSW; so the fresh samples or primary component have not enough indication to define the problem. In this paper, large-scale direct shear tests were performed on the real samples with different age and different percent of soil obtained from Alborz landfill in Qom city to investigate shear strength of materials in existing landfill and to expand the landfill. Other parameters such as overconsolidation and plastic content have analyzed. The results shows that shear strength have decreased with increasing in waste age and plastic content. In addition, with changing in soil amount to optimum percent shear resistance increased and then decreased. Overconsolidation without changing in compaction effort has mutated the mobilization of shear strength.