Seabed Ground Improvement in Coastal Reclamation Area by Heavy Tamping After Rockfilling Displacement

Abstract

Considering the characteristics of seabed ground in coastal reclamation area, ultra soft clay improvement method by heavy tamping after rockfilling displacement was proposed combined with a case study. The improvement mechanisms of the method can primarily be attributed to rockfilling displacement (RD), dynamic compaction (DC), dynamic replacement (DR) and dynamic replacement and mixing (DRM). For the case study given in this article, heavy tamping construction program was proposed based on field pilot tests. Furthermore, the effectiveness of the proposed ground improvement method was verified through in situ plate load test, sand fill test and the analyses of observed settlement data. Thus, the method of heavy tamping after rockfilling displacement is applicable for the improvement of seabed ground in coastal reclamation area. It is proposed for similar projects that heavy tamping of fills may be performed by layers and correspondingly tamping energy increased to further enhance the improvement effect of DC, DR and DRM. In addition, delayed improvement effect or time effect of soil mass after heavy tamping is still an issue to be further studied.

Keywords:

• dynamic compaction (DC)
• dynamic replacement (DR)
• dynamic replacement and mixing (DRM)
• heavy tamping
• rockfilling displacement (RD)
• seabed ground

This research work presented here was funded by the National Natural Science Foundation of China under Grant No.40406019 and Zhejiang Provincial Natural Science Foundation of China under Grant No.Y104281. These financial supports are gratefully acknowledged.