ANALYTICAL STUDY OF DOLOMITE SINKHOLES IN CENTURION, SOUTH AFRICA

摘要

Karst landscapes cover 15% of the earth's topography with an estimated 1.5 billion inhabitants residing on the land. Therefore restricting land uses and preventing infrastructure developments on dolomite land may be deemed highly impractical. As a result, infrastructure restrictions in karst areas have encouraged geotechnical professionals into developing geological models to simulate the magnitude of catastrophic subsidence experienced due to dolomite sinkholes. Sinkholes in dolomite are triggered by the alteration of the existing groundwater level within the karstic strata. In this study, the appraisal of sinkhole propagation was facilitated with the geological data acquired along the Gautrain route through Centurion, South Africa. This paper presents the conceptualized 'angle of draw' of dolomite overburden layers into cavities, with Terzaghi's arching in soil equation. The analytical results illustrated constant vertical drawdown in the weathered altered dolomite (WAD) and incremental cavity propagation in the frictional chert residuum. The sinkhole propagation results replicated previous physical modelling and empirical findings. This idealized analogy of sinkhole propagation compliments the quantitative assessment of empirical data, limit analysis and expert judgement applied to estimate dolomite sinkhole hazards.