Abstract: In order to determine reinforcement effects and technical parameters of dynamic compaction on roadbed, with silt and silty clay roadbed of a high speed railway as research object, bearing capacity and deformation law and features of reinforced roadbed by dynamic compaction at 15 and 20 m falling distances were studied through site experiment and numerical simulation. The results show that as tamping times increase, compaction settlement for each tamping decreases and gradually stabilizes, and settlements of last two tamping of each falling distance can meet termination condition of engineering design. When dynamic compaction is applied, water content, dry density and specific penetration resistance of surface soil are all significantly improved with obvious reinforcement effect achieved in efficient reinforcement area. And bearing capacity characteristic values of roadbeds in three test points are greater than 150 kPa, which meets designing requirements. In early stage of dynamic compaction, numerical simulation results are slightly smaller than those of field test, but they agree well with each other as tamping times increase.

Key words: railway roadbed, dynamic compaction reinforcement, bearing capacity, falling distance, compaction settlement