Observational design of underground cable bolt support systems utilizing instrumentation

Abstract

The observational approach to cable bolt design uses visual observations as well as data collected from rock mass and cable bolt instruments to gain increased understanding of the response of the rock mass to the creation of mining openings and the interaction between cable bolts and the deforming or failing rock mass. Predictions of rock mass and cable bolt behaviour, made from models, can be used to determine the type of instruments required in the programme and then to compare the predicted to the measured response. Increased understanding of the interaction between the cable bolts and the rock mass can lead to changes in the type or pattern of cable bolts specified in design. A case history based on a cable bolting instrumentation programme carried out at Ansil Mine illustrates many of these principles in practice. As a result of the findings of this case history, the cable bolt design for Ansil Mine was modified to take account of the anticipated conditions of mining-induced stress change.