Abstract: Considering the fact of no hard crust existed in the highway along coastal soft soils that can be used, this paper proposes the conventional surcharge method to create an artificial hard crust layer using manmade drainage measures based on the laboratory model test and numerical simulation results. Compared with the original soil layer, the improved soil reduces the deformation the vertical settlement at top of embankment by 20% and reduces the horizontal deflection at the toe of the embankment. In addition, the numerical analysis indicates that the differential settlement of the roadway surface in the manmade hard crust layer can also effectively be reduced compared with the original soft soils. With the special conditions in the coastal soft soil area, the other strengthening methods can also be introduced to improve the surface soil layer for the long term stability of highway embankment.

Key words: Costal Highway, Manmade Hard Crust, Model Tests, Numerical Simulations