Microstructure of unsaturated loess and its influence on strength characteristics.

Previous studies have shown that structure has a significant influence on the mechanical deformation of unsaturated loess, but there is little published information focused on the influence mechanism of microstructure and mesostructure on the mechanical properties of loess. In this paper, the unsaturated undisturbed loess and its remolded loess under the same physical condition were taken as the research objects. The unsaturated triaxial shear tests with constant suction and net confining pressure were carried out, and the microstructure differences between the two are compared by using SEM and CT scanning to reveal the influence of structure on strength characteristics. The test results show that the cohesion and internal friction angle of undisturbed loess are greater than those of remolded loess. The angle of undisturbed soil particles is obvious, and the particles are bracket contact with good cementation. The remolded loess particles are close to round shape, and the particles are inlaid contact with destroyed cementation. The average radius of undisturbed soil is higher than that of remolded soil, indicating that there are bracket pores in undisturbed soil, but the bracket structure and macropores are deformed during shear deformation, and good structural and cementation ensure the strength of loess specimens.