A new method of assessing the collapse sensitivity of loess

The damage caused by loess collapse after wetting is related not only to the magnitude of the collapse, but also to the resistance to and speed of the collapse. These factors are encapsulated in the concept of collapse sensitivity. However, there is no scientific and rational method available to evaluate it. To introduce this concept and develop a scientific evaluation method, four representative loess sites were selected in four different cities in China: Lanzhou, Xi’an, Taiyuan and Luoyang. Collapsibility tests were performed with loess samples from these sites. The concept of the collapse sensitivity of loess was introduced through the experiments, which involves the collapse magnitude, collapse speed and resistance to collapse. According to the physical significance of the concept, only two indexes, the time required to reach 90% of the collapse and the collapse potential under an appropriate pressure, were proposed to evaluate the collapse sensitivity of loess at a given site. The Chou Huang channel, which has collapsed, was presented as a case study to demonstrate the application and reliability of this method.