Abstract: Given the problems of post-construction settlement deformation of high liquid limit red clay low embankment in Southern China, the variation laws of vertical and lateral wetting strain of high liquid limit red clay under different confining pressures, ratios of axial pressure to confining pressure and compactness were studied using a self-designed test device which can test the wetting deformation of rock and soil under low stress conditions. A peak prediction model of vertical wetting strain of high liquid limit red clay considering the influence of confining pressure, ratio of axial pressure to confining pressure and compactness is further established, and the prediction model is validated. The primary conclusions are as follows: under the coupling action of seepage and stress, the lateral wetting strain and vertical deformation of high liquid limit red clay first increase and then tend to be stable. When the wetting deformation is stable, the high liquid limit red clay sample shows the characteristics of large upper part and small lower part. The duration of lateral wetting strain, peak value of lateral wetting strain and peak value of vertical deformation of high liquid limit red clay are positively correlated with confining pressure and ratio of axial pressure to confining pressure. The peak value of lateral wetting strain and peak value of vertical deformation of high liquid limit red clay are negatively correlated with the degree of compaction, and the duration of lateral wetting strain is positively correlated with the degree of compaction. The lateral wetting strain of high liquid limit red clay can be divided into two parts: the lateral wetting strain caused by humidification and the one caused by water absorption of expansive minerals. The importance of different factors on the vertical wetting strain peak of high liquid limit red clay is: compactness > ratio of axial pressure to confining pressure > confining pressure. This study has an important engineering significance for the prediction and control of post-construction settlement deformation of low embankment with high liquid limit red clay.

Key words: road engineering, high liquid limit red clay, low stress, lateral wetting strain, vertical wetting strain, forecast model