Application of Dynamic Replacement Soil Improvement Method to an Early Site Preparation Works Project in Saudi Arabia

Early site preparation works were required for a big capital project site located close to the Arabian Gulf Coast in the Eastern Province of Saudi Arabia. The ground conditions at the delineated area at site comprise 5 to 6 m thick of very loose Silty Sand interbedded with Silt & Soft Clay, overlying medium dense to very dense silty Sand. The scope of the early site works within the delineated area (approx. 1.1 million sq.m) on site was limited to soil improvement by applying the Dynamic Replacement (DR) soil improvement due to the very high fines content of upper soils and the unsuitability of utilizing conventional mechanical compaction, e.g. Dynamic Compaction (DC) & Rapid Dynamic Compaction (RDC). The DR method was utilized to reduce the compressibility, improve the density and increase the bearing capacity of the underlying soils prior to the application of approx. 2 m thick fill across the site to reach desired final grade level. Pre and Post CPTs were undertaken at the site for initial calibration trial and post quality assurance of the main DR works. The results of the post quality tests show significant improvement of the soil, and the acceptance criteria of 100 kPa for a footing of 3 m by 3 m set for the project were met.