Experimental Study on Water Sensitivity of the Red Sand Foundation in Angola

Abstract

In Angola’s capital Luanda and its surrounding areas, there distributing abundant brownish red sand called Quelo, which possesses the characteristics of softening and collapsibility when immersed with water. So how to improve the red-sand foundation reasonably and economically is of vital importance and urgency for the infrastructure construction of the area. Based on certain housing project in a typical red sand site in Luanda, a large in-situ water immersion experiment on the site was performed, which simulate the foundation treatment of replacement cushion, foundation dimension and load value of actual buildings. This paper records this experimental study and aims to investigate into the effectiveness of foundation treatment method, this paper records and studies the water-immersion deformation of the foundation after treatment and the rules of water permeation. The results show that: (1) the special formation structure of the red sand site determined a wider impacted area after water immersion; (2) the mudstone distributed under the red sand layer may expand slightly after water immersion; (3) the indoor test tends to exaggerate the hazard of red-sand collapsibility; (4) the bearing capacity of red-sand after softening with water-immersion should be adopted in the foundation design of multi-storied residential buildings on the red-sand site, and (5) the foundation treatment of replacement cushion is effective and reasonable.