Characterization of the collapsible mechanisms of Malan loess on the Chinese Loess Plateau and their effects on eroded loess landforms

摘要

Collapsible loess soils are widely distributed in semiarid and arid regions. The eroded landforms formed by the unique collapsibility of loess may cause environmental damage that puts lives and property at risk. In this work, the collapse potential, quantitative analyses, and qualitative characterization of the microstructures of loess samples were investigated using double oedometer tests, scanning electron microscopy (SEM), and the digital image analysis method to probe the fundamental mechanisms of loess collapsibility. A large number of field investigations have been carried out to study the role of loess collapsibility during the formation of eroded landforms. The results show that the collapse potential of loess first increases and then decreases in response to increasing vertical pressure. Loess from the different study regions exhibits different microstructure types. Loess collapse is mainly caused by the destruction of large and medium pores, although the contribution of the middle pores on the collapse is more significant. The microtopography formed by loess collapse is conducive to surface runoff concentration and infiltration. The eroded landforms resulting from loess collapse are categorized into four different models based on the catchment area and the discharge area. These results and analyses are important to land use planners and engineers and will aid in controlling and mitigating disaster-prone landforms.