Field Evaluation of Dynamic Compaction on Granular Deposits

Abstract

The dynamic compaction (DC) method is a versatile ground treatment technique with growing popularity. It is applicable to a wide variety of soil types and conditions, particularly sandy materials and granular fills. This study presents a case history of the dynamic compaction with a high energy level of 6,000 kN·m on granular deposits at a site in China. The reclaimed site featured loose backfill with heterogeneity and saturated silt. In order to properly deal with such soil conditions and to optimize the DC design, field tests were conducted to determine the influencing factors in DC. Deformation tests were performed to ascertain the rational spacing of impacts and the optimal number of drops and to provide proofs to the adjustment of the original DC procedure. Monitoring of the pore water pressure helped obtain the time delay between passes. The approach to assess the depth of improvement was discussed based on interpretations of the spectral analysis of surface waves (SASW) test. Analysis of the SASW and plate-load tests demonstrated significant improvement in the soils at the site, with no obvious weak layers. Following dynamic compaction, the allowable ground-bearing capacity and the depth of improvement at the site were no less than 270 kPa and 7.4 m, respectively.