Crack development and coalescence process in drying clayey loess

The Chinese Loess Plateau is located in northwestern China. During investigations in loess fields, it was found that, under dry climatic conditions, cracks were prone to appear and propagate in the loess plateau. The presence of cracks and their effect on the engineering properties of loess greatly influence the stability of soil-based structures and can cause severe damages. The purpose of this research was to analyze the drying-induced cracking mechanisms in clayey loess, and to highlight the effect of soil mineralogy. Laboratory tests were performed to simulate the cracking process in loess. The analysis is based on the local two-dimensional strain and displacement fields derived from the Digital Image Correlation (DIC) method and the software VIC-2D. The determination of the mechanical strain tensors, i.e. the difference between the total strain and shrinkage strain tensors, and their visual representation allow a deeper understanding of cracking mechanisms. Based on the above methods, crack development and crack coalescence processes were observed and analyzed. Besides, other mechanisms were identified, such as junction and bifurcation of cracks.