Evolution of micro-structure and macro-structural property of loess

As a kind of under-compacted structural soil, the loess is easily damaged by consolidation, shear and Immersion, which makes the mechanical properties change with the evolution of soil structure.From the point of view of observing the evolution of loess micro-structure, the initial structures of natural, remolded and saturated loesses, the triaxial consolidation completed structure with different confining pressure and the triaxial shear failure structure are tested by the micron CT tests.The mechanical behavior of the deformation of the soil skeleton is explained from the perspective of soil structure.The main results include:(1)The saturation and disturbance remodeling change the soil-particle-bound water film, eliminate the distribution of large pores in soil skeleton, and homogenize the distribution of soil pores.(2)Under the same confining pressure conditions, the macropores tend to decrease with the development of the consolidation shear deformation of soil samples.When the consolidation of undisturbed soil is completed, there are still obvious large cracks, and when the shear failure occurs, the soil produces obvious shear shrinkage deformation, and the distribution of large holes in the soil skeleton is significantly reduced.(3)Compared with the undisturbed soil, the remolded soil has more uniform distribution of skeleton, and its macropores are basically closed when shearing.The saturation and consolidation shear can make the macropores disappear completely.(4)By controlling the loading and unloading with different strain levels, it is revealed that the structural degree of soil structure decreases with the increase of the comprehensive plastic strain, and the strength of soil also decreases.