The use of rock mass classification systems in assessing the long term stability of underground openings.

Long term stability of the limestone mines in the South of The Netherlands is assessed with the Q-system for rock-mass classification. Rock-mass classifications are calculated for different mines and mine areas. The predicted stand-up times up to 500 years seem to correlate very well with reality. One mine is assessed in more detail and a remarkable correlation exists between the Q-system values, span width and the degree of fracturing of the pillars. Using the Q-system for predicting future stability of the limestone mines leads to the conclusion that some mines are at the end of their lifetime and that collapse might be imminent.