Application of High Energy Dynamic Compaction in Coastal Reclamation Areas

Abstract

High energy dynamic compaction (HEDC) is adopted in a coastal reclamation area because the grain size of backfilled soil mostly ranges between 20 cm and 100 cm. The in situ tests for evaluating the effectiveness of HEDC were performed on the backfilled soil ground. The crater depth per drop and the whole test zone elevations before and after HEDC were measured and analyzed. Dynamic penetration tests and spectral analysis of surface wave (SASW) tests were used for investigating the improvement depth. Furthermore, the allowable bearing capacity of HEDC treated ground was determined based on the results of plate-load tests. It was found that HEDC did not cause the ground surface heave during construction, and was more effective than low energy dynamic compaction (LEDC) in terms of applied energy utilization. Based on the test results, the improvement depth of HEDC at this site was not less than 14 m, and there was no obvious weak layer within the range of improvement depth. The allowable bearing capacities were larger than 160 kPa. The investigation results indicate that the HEDC technique is an effective way for improving backfilled coarse-grained soil in coastal reclamation areas. This technique helps to achieve both greater improvement depths and higher ground bearing capacities as compared with LEDC.

Keywords:

• bearing capacity
• field test
• high energy dynamic compaction (HEDC)
• improvement depth

The authors wish to thank J. L. Zhan, J. L. Yang, and X. C. Cheng for their assistance in field testing work. Much of the work described in this paper was supported by the National Natural Science Foundation of China under Grant No. 50708079, the Research Fund for the Doctoral Program of Higher Education under Grant No. 20070247041, Shanghai Twilight Program under Grant No. 2007CG23, and the Programs for Young Excellent Talents and Outstanding Young Teachers in Tongji University. The authors would like to greatly acknowledge all these financial supports and express the most sincere gratitude.