Abstract
The lag between a shaft face and the permanent concrete liner has a significant impact on the liner’s long-term health and therefore its performance during the life of the mine when it comes to deep mining. A short lag would impose the liner to unnecessary induced stresses while a larger lag would impose shaft workers to the risk of ground fall and rockburst. Finding an optimal time for concrete pour requires a deep knowledge of the rock mass properties as well as a proper understanding of the response of the rock environment to the shaft sinking process.
This paper presents the process of finding such a balance point through 3D numerical modeling of the shaft sinking process at KGHM’s Victoria Project in Sudbury, ON. It will be shown how proper sequencing of blasting, temporary ground supporting, and concrete pour would reduce the liner's induced stresses and prevent stress-induced cracking.