By the FEM numerical method

the characteristics of loading and deformation in widened highway subgrades with retaining wall in mountainous areas are discussed. The results by FEM show that in the subgrade-widening project in mountainous area

settlement curve of the subgrade features the shape of scoop; in contrast with the one in the shape of parabola in new-built highway; not only the treatment of jointed section between new and old highway subgrades

which is the key task in normal widened highway subgrade

but also the treatment of jointed section between new highway subgrade and retaining wall should be stressed in the subgrade-widening project in mountainous area; the lateral earth pressure distribution of retaining wall exhibits nearly a parabolic curve

different from the triangle form by classical earth pressure distribution theory. The analyses on the effects of the widened extent

the slope of old embankments and the different characteristics between the old and new materials of subgrades

reveal the rule of uncoordinated deformation between the new and old subgrades

and the characteristics of the lateral earth pressure distribution of retaining wall.