Abstract: To investigate the coupling properties and laws of the deformation and the shear strength of fresh municipal solid waste (MSW), the compression-direct shear combined tests have been carried out by using large-scale combined test apparatus of compression and direct shear. Ninety-six fresh municipal solid waste samples were prepared in geoenvironmental laboratory. The initial void ratios of the samples were selected as 2.1, 2.5 and 2.9. Four different vertical pressures 25, 50, 100, and 200 kPa, were chosen; and the compression times for every vertical load were 0, 0.25, 0.5, 1, 2, 6, 12, and 24 hours, respectively. The testing results show that: (1) The relationship between shear stress and shear strain under different compression times is in conformity with a hyperbolic model; model parameter a varies from 0.028 to 0.144; and model parameter b varies from 0.012 to 0.024. (2) A multinomial model can be used to express the relationship between shear strength and compression strain (compression time) under different vertical pressures and different limit values of shear strain, the values of model parameters are given, and the correlation coefficient of the model is found in the range of 0.63-0.98. (3) The relationship between shear strength and vertical pressure applied on the sample under different initial void ratios complies with Coulomb’s law. Besides, shear strength parameters of the MSW are obtained; the cohesion force varies from 11.1 to 34.2 kPa; and the internal friction angle varies from 11.2 to 30.6 degree.

Key words: fresh municipal solid waste, shear stress, compression strain, shear strain, shear strength