黄土的特殊工程性质，导致其所在地区公路涵洞病害时有发生。为了解决湿陷性黄土地区不良地基导致的涵洞工后沉降过大的问题，以青海民和—小峡一级公路湿陷性黄土地区的2座涵洞为例，分别采用灰土换填法和灰土挤密桩法对这2座涵洞地基进行处理，地基处理后对这2座涵洞进行为期1 a的沉降监测。结果表明采用灰土换填法和灰土挤密桩法1 a累计沉降量分别为25.0 mm和18.2 mm，灰土换填法和灰土挤密桩法都能有效消除涵洞地基因浸水而引起的湿陷变形，较大幅度地提高地基承载力。地基处理1 a后沉降趋于稳定，与灰土换填法相比，灰土挤密桩法对降低压缩变形、提高地基承载力更加有效。研究成果可为湿陷性黄土地区公路涵洞的设计施工提供参考。

Special engineering properties of loess often lead to hazards of highway culvert in the loess area. In order to address the problem of post-construction settlement of highway culvert caused by poor foundation in collapsible loess area, we treated the foundations of two highway culverts on collapsible loess area of the highway from Minhe to Xiaoxia in Qinghai province as a case study by replacing loess with lime-soil (hereinafter referred to as replacement method) and by filling lime-soil into boreholes for compaction (hereinafter referred to as compaction method), respectively, and monitored the settlements of the treated culverts for one year. Results revealed that the accumulative total settlements of culvert treated by the two methods were 25.0 mm and 18.2 mm, respectively. Both the methods could effectively eliminate the collapsibility deformation of highway culvert caused by water immersion and remarkably improve the bearing capacity of foundation. Foundation settlements became stable in a year after the foundation treatment. The compaction method is more efficient in eliminating deformation and improving bearing capacity than replacement method. The research result serves as a reference for the design and construction of highway culvert in collapsible loess area.