ABSTRACT
From detailed geotechnical investigations for a smelter complex on the outskirts of Maputo in southern Mozambique, a composite stratigraphic column has been compiled for the upper Cretaceous and overlying Neogene marine sediments. It is proposed that the 6m thick diagnostic Pectenid-rich calc-arenite of Miocene age be termed the Matola Formation.
A Pliocene marine transgression reworked reddened aeolian dune sands with deposition offshore to form a tabular fine sandstone. Subsequent exposure and weathering during the Pleistocene has resulted in a 15–20m thick potentially collapsible residual soil profile. Collapse settlement potential of up to 13% occurs at saturation loads of 1000kPa. As a result, initial pile design was revised to allow for this geotechnical hazard. The critical degree of saturation for the red soil mantle is approximately 30%, which corresponds to a moisture content of 6%-6,5%.
