考虑卸荷作用的黄土湿陷性评价方法研究

卸荷作用会导致湿陷性黄土部分湿陷量未发生，但目前黄土湿陷性评价方法中未考虑卸荷因素的影响。推导并建立了卸荷条件下黄土湿陷系数的表达式，并通过卸荷湿陷试验确定了表达式中的参数取值。首先定义湿陷完成比、卸荷应力比分别用来表征卸荷作用发生前黄土湿陷变形的完成程度及卸荷作用发生时卸荷量的大小。运用湿陷完成比及卸荷应力比推导出卸荷湿陷系数的计算公式。该公式揭示出卸荷湿陷系数是对湿陷系数一定程度的折减，而该折减与湿陷完成比及卸荷应力比有关。随后进行黄土在不同湿陷完成比和卸荷应力比下的卸荷湿陷试验，得到上述条件下黄土卸荷湿陷量的取值。对试验结果进行分析得到卸荷湿陷系数的具体表达式。该公式可用于计算在不同初始压力下，任意湿陷完成比及卸荷应力比下的卸荷湿陷系数。通过对比卸荷湿陷系数的试验值与计算值验证了所推公式的合理性及准确性。得到了考虑卸荷作用的黄土湿陷性影响系数的确定方法，进一步总结了卸荷作用对黄土湿陷性的影响规律。

A method for evaluation of loess collapse potential of unloading

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.