Design methodology for the safety of underground rock engineering

In order to optimise the safety of underground rock engineering construction and the long-term security of the resultant facilities, it is necessary to have a knowledge of the likely hazards. These risks or hazards fall into the four categories of "known beforehand and relatively easily addressed", "known beforehand and not easily addressed", "not known beforehand and relatively easily addressed", and "not known beforehand and not easily addressed". This paper describes how these four types of hazard can be incorporated into a design methodology approach, including the process by which the relevant mechanical rock mass parameters can be recognised for modelling and hence predictive purposes. In particular, there is emphasis on the fact that information and judgement are the keys to safety——whether the hazards are known or unknown before construction proceeds.