An experimental study on the behavior of loess-clay mixtures upon wetting and its implications for tillage on the Loess Plateau

Abstract

Loess formation is widely distributed throughout the world and appears often in the form of a loess and clay mixture. The wetting-induced collapse in such ground conditions is a major concern for protecting tillage land. In this study, we present a simple model for the assessment of wetting-induced collapse in such loess-clay mixtures. Our approach is based on easily accessible oedometer tests by considering the change in dry density, water content, and clay content. Moreover, our model is underpinned by examining the soil structure during wetting deformation with the help of scanning electron microscopy. We demonstrate that the wetting deformation is dictated not only by the physical soil properties but also by its microstructure. Based on the experimental findings, we introduce an index for the yield stress of loess-clay-mixture. We proceed to develop a model for the assessment of collapsibility and show how this model can be used in engineering practice.