Collapse of residual archaen granitic soils in South Africa

Abstract

The collapse of residual Archaen granitic soils in South Africa is a geotechnical hazard that was identified in the 1950’s. Collapse has led to hazardous building conditions in the rapidly expanding northern parts of Johannesburg, and in areas stretching across the eastern parts of South Africa, encompassing KwaZulu Natal, Mpumalanga and Limpopo Provinces. Since the development of the oedometer test in the 1960’s and the research of Jennings and Knight in the 1970’s very little further research has been done on the topic of collapse, despite the development of a number of new testing procedures that can give insight into the properties of these soils. Due to the large surface area of South Africa prone to collapse, and the lack of knowledge and testing methods to identify and quantify this hazard the author felt, that further insight into the collapse of residual Archaen granitic soils was required. This research serves to evaluate the properties of Archaen residual granitic soils that may be indicative of collapsible soils. The research also compares various test methods and apparatus used to identify and quantify collapse potential, namely the oedometer collapse potential test and the triaxial collapse potential test, and evaluates the effect of soil properties on these methods.