Abstract: In order to explore the stress and deformation characteristics of widened embankment which directly built on soft ground under static loading, a self-designed and self-made model test system is adopted. A series of model tests are carried out on this test system. By changing the value of the differential settlement and the layers of geogrid, variation characteristics of the soil stress in the old and new widened embankments are studied. The test results show that the vertical stress in the soil of both new and old sections of widened embankment increases with the load increase. The vertical stress decreases at first, then increases and finally decreases along the depth direction under the influence of the filling slope of embankment and the underlying foundation with lateral restraint. The differential settlement of the widened embankment built on soft ground has significant influence on the vertical stress at the junction between the old and new roads, the vertical stress in this area increases with the differential settlement, while the vertical stress in the old road is rarely influenced. Vertical stress and settlement of the embankment can be obviously reduced when geogrid reinforcement layers are laid at both the top and bottom of the widened embankment. Compared with non-reinforced embankment, the settlement on the top surface of embankment reinforced with 2 layers of geogrid can be reduced by 62% at most, which shows the geogrid reinforcement has a good control on the settlement of embankment built on soft ground.

Key words: soft ground, model test, widened embankment, geogrid, soil stress