A new and simple method for predicting the collapse susceptibility of intact loess

Abstract

The collapse susceptibility of intact soil should be determined before designing infrastructures in loess regions. It is significantly affected by many factors, including soil type (i.e. sandy, silty or clayey loess), moisture, porosity, stress and structure. So far, many relevant empirical equations and theoretical models were reported in the literature. Each empirical equation has a narrow application range and the theoretical models cannot be easily calibrated. In this study, a new and simple method was developed to predict the loading- and wetting-induced collapse of intact loess within the elasto-plastic framework. The compression curves of intact loess under saturated and unsaturated conditions were normalised using the void index and applied to analyse the loading- and wetting-induced collapse. This method can readily be used by engineers to predict the collapse potential in a wide range of loess types and conditions, with the input of only three state variables (i.e. initial void ratio, vertical stress and initial water content) and the void ratio at the liquid limit state. To verify this new method, it was applied to simulate about 200 laboratory wetting tests and one in-situ ponding test. The measured and predicted results are reasonably matched, demonstrating a good capability of the method.