Experimental study on the disintegration of loess in the Loess Plateau of China

Abstract

The strength and mechanical behaviour of loess are especially affected by water, and loess tends to disintegrate in the presence of water. Loess disintegration is closely related to the formation of caves, rills, and gullies on slopes and landslides. In this study, we conducted in situ tests and laboratory tests on Q3 Malan loess using self-developed disintegration instruments (small and large test blocks) to determine the characteristics and mechanisms of loess disintegration and their relationships with influencing factors such as initial water content, structure, curvature, and surface shape. The results show that the disintegration behaviour of loess conforms to a dynamic model. We propose that the fragmentation process and the breaking process are instantaneous and irreversible, whereas the separation process requires more time and is somewhat reversible. The disintegration time of the loess was controlled by the wetting velocity. An investigation of the boundary effect on the disintegration of the loess indicated that the presence of a disintegration nucleus was the result of slower water penetration of the inner layer caused by the temporary boundary confinement of the outer wetted layer. The boundary effect became more obvious with decreasing the water depth, increasing the curvature of the slot surfaces, and sharpening the edges of the convex upright in situ samples. The results of this study are intended to provide basic theoretical support for soil and water conservation and engineering construction in loess areas.