DEM analysis of evolution law of bond degradation for structured soils

The evolution of bond degradation is essential for analyzing the macro-and micro-scopic behaviors and establishing constitutive models for structured soils with cementation bond which is a kind of bonded granular material. The discrete element method is employed to analyze the evolution of bond degradation on account of the disadvantage of laboratory tests in bond breakage quantitative analysis. First, the discrete numerical sample is generated by installing a relatively completed bond contact model incorporating the interparticle rolling and twisting resistances and the influences of bond size on the contact stiffness and strength. The DEM simulation reproduces the key mechanical behaviors of one-dimensional compression, isotropic and anisotropic compressions, conventional triaxial and true triaxial tests on the DEM sample. The results show that the evolution of the degradation variable B₀ is stress-path-dependent, while a new degradation variable B_σ is roughly stress-path-independent. An exponential function is recommended for B_σto describe the degradation of soil structure.