Earth Foundation Treatment at Jebba Dam Site

The Jebba Main Dam is founded on alluvial sands up to 230 ft (70 m) in depth. Soil investigation established the presence of locally loose materials at various depths. The test methods of the original investigation are described, and the soil parameters measured are presented. A short description of design considerations is followed by a detailed description of field tests with different vibrocompaction equipment, deep blasting, and penetrometer equipment. Production work included densification of approximately $308\text{,}700{\mathrm{yd}}^3$ $\left(236\text{,}000m^3\right)$ by deep blasting and $3\text{,}492\text{,}200{\mathrm{yd}}^3$ $\left(2\text{,}670\text{,}000m^3\right)$ of foundation materials by vibrocompaction method, and represents one of the largest groundimprovement programs ever undertaken.