Stability analysis of underground openings in an abandoned gold mine using rock mass classifications and numerical methods

The stability of underground caves in an abandoned gold mine was carried out through a series of geotechnical investigations. After the closure of the mine, both the natural caves and the man-made underground openings were converted to a tourist route since 1990’s. Detailed field investigations including Rock Mass Rating (RMR), Geological Strength Index (GSI) and Q classification were performed to evaluate the stability of the caves and to design reasonable support systems of the unstable openings. Rock fall analysis has been carried out on the rock masses of the largest cave where discontinuities were investigated by the multistage convergent photographing method. Three dimensional numerical modeling has been conducted using MAP3D software package to examine the stability of the mine openings. Based on the results of rock mass classification and numerical analysis, suitable support design was recommended for mine openings.