Settlement and deformation characteristics of high fill of Luojiahe expansive soil in Ankang Airport

The Luojiahe high fill of Ankang Airport is a rare expansive soil fill in China. In this study, the settlement characteristics of fill are studied by monitoring the settlements of surface and bottom culverts. The results show that the surface settlements of expansive soil at the secondary consolidation stage of high fill are significantly affected by precipitation, and the repeated expansive deformation occurs with the maximum expansion rate of 0.485 mm/d. The prediction model for the post-construction settlement of high fill of expansive soil is established incorporating the fill thickness and settlement duration. The model parameter u can represent the settlement caused by the drag effects caused by the foundation settlement at the interface of the cut and the fill. The average relative error of the value is 12.17%. This model can be used as a reference for predicting the post-construction settlement of projects with similar geological conditions and filling materials. The expansive and compressive deformations of the fill can be divided into 8 stages. The monitored deformation stages are closely related to the precipitation in the period. The rainfall at the slowly rising stage Ⅶ is 644 mm, and the corresponding expansive deformation is 44 mm. The expansive soil fill generally shows expansion rather than compression of other geotechnical fills.