Laboratory studies of the dynamic characteristics of mechanically-biologically treated waste

The dynamic characteristics of landfills under seismic loading and their stability strongly depend on the cyclic stress-strain characteristics of the waste. An accurate assessment of the dynamic characteristics of mechanically-biologically treated (MBT) waste is crucial to the construction and safe operation of landfills. Considering the effects of the confining pressure, strain amplitude, and loading frequency, 72 sets of consolidated undrained cyclic triaxial (CTX) tests were conducted on MBT waste. Our results showed that the dynamic stress amplitude of MBT waste increases with increasing strain amplitude and decreases with increasing number of cycles. Furthermore, the shear modulus of MBT waste increases with the increase in the confining pressure and decreases with the increase in the strain amplitude. By increasing the strain amplitude, the damping ratio of MBT waste increases. However, the shear modulus and damping ratio of MBT waste are less affected by the loading frequency. A modified Davidenkov model is presented, which describes the correlations among the normalized shear modulus of MBT waste, shear strain, and confining pressure. The fitting parameters are discussed, and the correlation between the normalized shear modulus and shear strain of MBT waste and that between the normalized shear modulus and shear strain of municipal solid waste were compared. The results of this study can be used as references for analyses of the dynamic stability of MBT landfills.