Abstract: The proposed Wangjiadun Duishan Park is on the soft soils. The combination of sandgravel columns and dynamic compaction methods are found to be most economical. To verify the feasibility of this soil improvement concept, the pilot study was conducted at two locations. The effect of the improvement was evaluated by the Dynamic Penetration Test (DPT) method. The DPT testing was performed at soils between sandgravel columns. From the DPT blow count changes before and after the improvement, it is concluded that the shear strength of the composite soil mass was improved after the installation of the sandgravel columns. After the dynamic compaction, the shear strength of the deep deposited soils increased but the soil strength at shallow depth decreased.

Key words: improvement, sand-gravel columns, dynamic compaction, dynamic penetration test