Abstract: High liquid limit soil has some characteristics such as high natural moisture content, high plasticity, high void ratio, and low compactness. Finding the settlement deformation law of high liquid limit soil embankment becomes the key to use it scientifically and reasonably. Based on the mechanical properties of high liquid limit soil, a 26.5 m high embankment was constructed using high liquid limit soil and a long-term settlement observation was carried out. Observation results show that the road settlement value is very high during the subgrade construction; the settlement is smaller in the natural sedimentation time; and the settlement is very small after the pavement construction, about 0.2% of the height. The settlement value is proportional to the subgrade height. Adopting simplified unsaturated soil consolidation theory, the settlement and deformation of high liquid limit soil have been calculated; the calculation results is basically identical with the measured settlement of high liquid limit soil embankment, consolidation theory of unsaturated soil provides a new technical mean for high liquid limit soil embankment settlement calculation. The results prove the post-construction settlement of high liquid limit soil will not be larger; so as to provide a technical basis for its popularization and application in highway engineering.

Key words: high liquid limit soil embankment, settlement deformation law, unsaturated soil theory