Under the conditions of drought, cracks are likely to appear in loess due to shrinkage, which leads to salt precipitation and accumulation on the surface of loess. Therefore, salinized lands are created in loess areas. Deep study into the influence of soluble salt content on the cracking characteristics and mechanism of loess is of great significance to engineering constructions, geological problems, and disaster prevention for salinized lands in loess regions. In this paper, free desiccation experiments were carried out on the loess samples with different NaCl concentrations (a soluble salt). A high-resolution digital camera was used to obtain the sequence images of loess during the drying process. With the advantage of digital image correlation (DIC) technology and the non-contact full-field strain measurement method, the local displacement and strain on the surface of loess samples were calculated. The microstructure and main elements distribution of loess samples were obtained by scanning electron microscopy (SEM) and energy-dispersive spectrum (EDS) methods. Finally, the influence of NaCl concentrations on cracking characteristics and mechanism of loess was analyzed. The results show that, with the increase in NaCl concentration, the evaporation rate of loess samples decreased and the residual water content increased. The NaCl content can prevent the development of desiccation cracks in loess.

Loess is a special soil with high water sensitivity which covers a large area in Northwest China. Cracks are prone to generate in loess under the arid and semiarid climates, which will provide a preferential channel for water and reduce the mechanical properties of soils. It is of great significance to understand the evolution characteristics and mechanisms of the cracks in loess areas. At present, research on cracks in soils mainly concentrates on the characteristics of different cracking patterns. However, spacing cracks are mostly discussed in materials like rock and concrete rather than soils. The cracking characteristics and mechanisms of spacing cracks in loess are still inadequate. In this research, drying tests of loess are carried out with different sizes of specimens. The parameters of spacing cracks and local strain distributions of the loess samples are obtained via PCAS and DIC methods during desiccation, respectively. The cracking modes, spacing cracking laws like insertion, and the saturation of spacing cracks are revealed. Finally, the size effect on the characteristics of spacing cracks is verified with the discrete element software MatDEM.

Loess is a special soil with high water sensitivity, which covers a large area in northwest China. Cracks are prone to generate in loess under the arid and semi-arid climate, which will provide the preferential channel for water and reduce the mechanical properties of soils. It is of great significance to understand the evolution characteristics and mechanisms of the cracks in loess areas. At present, the researches on cracks in soils are mainly concentrated in the characteristics of different cracking patterns. However, the spacing cracks are mostly discussed in materials like rock and concrete, rather than soils. The cracking characteristics and mechanisms of spacing cracks in loess is still inadequate. In this research, the drying tests of loess are carried out with different sizes of specimens. The parameters of spacing cracks and local strain distributions of the loess samples are obtained via PCAS and DIC methods during desiccation, respectively. The cracking modes, space cracking laws like insertion and saturation of spacing cracks are revealed. Finally, the size effect on the characteristics of spacing cracks is verified with a discrete element software MatDEM.