Site investigation problems in residual soils of some Birrimian rocks of Ghana

The Birrimian rocks are structurally complex and extensively weathered in most places. The transition from rock to soil in the formation is often rather imperceptible. With just the basic site investigation equipment available in the country, site investigation in the residuals of the Birrimian rocks could be challenging. The only way to avoid over-designing is patient and systematic analysis of investigation data based on full understanding of the geology of the material at every site. This paper analyzes the problems associated with the Birrimian residuals encountered during site investigation at over sixty sites within the Birrimian, highlights solutions prescribed, and shows how a judicious combination of rock and soil mechanics principles could lead to reasonable solution of site investigation problems in soils with predominant structural features.