Stress-strain behaviour and shear strength of Municipal Solid Waste (MSW)

An understanding of the stress-strain behaviour of Municipal Solid Waste (MSW) is important in landfill design and stability analysis of landfill slopes. A series of triaxial compression tests were carried out on reconstituted MSW specimens. The effect of stress path on the drained stress-strain response and shear strength of MSW were investigated. For the compression stress paths of Δσ3≥0, a straight-lined increase section and an upward curvature are observed in the stress-strain curves of MSW; the upward curvature results from the fibrous constituents (primarily plastic and paper) reinforcing the waste matrix; the hardening points defined in stress-strain curves are used as failure criterion to calculate the strength parameters of MSW. For the compression stress paths of Δσ3 < 0, the stress-strain responses of MSW exhibit a rapidly increasing section towards a slowly increasing section without upward curvature; the development of fibrous reinforcement is not enough due to the reduction of confining stress σ3; the failure points defined in stress-strain curves are also used as failure criterion to calculate the strength parameters of MSW. A new method to estimate MSW strength parameters is proposed in this study. The differences of MSW friction angle are very small for different stress path tests. However, the cohesions obtained in compression stress path tests of Δσ3 < 0 are much smaller than that in conventional triaxial compression tests.