Aspects of advanced grouting during shaft sinking in South Africa

Abstract

Fixed costs for shaft sinking operations are extremely high, therefore precautions must be taken to avoid unproductive standing time of the shaft sinking crew. Water in-rushes or unconsolidated grounds sometimes cause stoppages to sinking operations because the sidewalls must be sealed or stabilised. Pregrouting can to a large extent avoid such delays. The paper describes ways and means how to execute pregrouting under varying conditions and draws attention to problems which may be encountered. The author concludes that the cost for preventive grouting operations are small compared with the overall expenses of shaft sinking operations and the cost of unproductive standing time.