Journal of the South African Institution of Civil Engineering
On-line version ISSN 2309-8775
BREYTENBACH, I J and BOSCH, P J A. Application, advantages and limitations of high-density gravimetric surveys compared with three-dimensional geological modelling in dolomite stability investigations. J. S. Afr. Inst. Civ. Eng. [online]. 2011, vol.53, n.2, pp. 7-13. ISSN 2309-8775.
The article discusses the nature of the gravimetric survey as applied and used in dolomite stability investigations on areas underlain by the Chuniespoort Group in South Africa. A short discussion is given on the gravimetric survey procedure along with its uses and alternative methods. Finally, two case studies illustrate the application of the method on a high-density survey grid spacing in comparison with three-dimensional geological modelling based on the lithology and karst weathering horizons of the Chuniespoort Group deduced from rotary percussion borehole data and limited rotary core borehole data. The two different case studies highlight the advantages and limitations of the high-density gravimetric survey. The first case studies shows that the high-density gravimetric survey can be applied to great effect to sites with a complex, variable profile, provided the grid spacing of the survey is adequate to identify the sub-surface features. Simultaneously, the findings of the second case study illustrate how the method has exactly the same limitations as regular gravimetric surveys if the scale of the grid is not compatible with sub-surface conditions.
Keywords : dolomite; gravimetric survey; rotary percussion drilling; three-dimensional geological modelling; karst.