Abstract: The segmental collapse of loess will not occur because of unloading. But loess collapse potential is generally evaluated without considering the influence of unloading. The coefficient of unloading collapse is obtained by unloading collapse test. The completion ratio of collapse is defined to represent the degree of loess collapse before unloading. The unloading ratio is defined to represent the degree of unloading. The calculation formula of unloading collapse coefficient is derived by completion ratio of collapse and unloading ratio. Through unloading collapse test, the unloading collapse of loess is measured in different unloading and collapse conditions. The specific expression of the unloading collapse coefficient is obtained by analyzing test results. It is suitable to calculate unloading collapse coefficient in either initial pressure, unloading amount and collapse condition. The calculated results based on the proposed equation are in good agreement with the test results. The loess collapse deformation have been further summarized by defining coefficient of collapse potential under the condition of unloading.

Key words: unloading, loess collapse potential, collapse coefficient, unloading collapse coefficient, finished collapse ratio, unloading ratio