Abstract: The compaction character experiments under different compaction degrees showed that the CBR value increased with the filling compaction degree increasing; the filling is provided with nicer compaction property, so it can be used for highly weathered soft rock to fill high grade highway embankment. Triaxial shear apparatus with an approximate actual stress path was used to do dry-wet crewel parallel experiment and wetting deformation experiment of different compactions under complicated stress function. The result shows that crazing and plastic destruction will not take place on road surface when the critical strain value is 2 %，the slaking deformation is reduced with compacting factor of the samples increasing and the shear swelling deformation is increased with deviator strain increasing when ? 3 equals to 200 kPa. Testing results are applied to subgrade embankment of the Zhaoshan Road in Xiangtan city, and construction measures of the embankment of clay in 95 area, wetting embankment and increasing compaction degree of the filling in 90 area are put forward.

Key words: highly weathered soft rock, slaking deformation, compacting degree, embankment for subgrade