Risk evaluations for stope mining affected by slope surface

This study describes the importance on the evaluation of rock mass condition before mining and probability of failure during mining under slope surface in shallow depth. It is well known that several factors can affect the stability of underground openings such as the quality of rock mass, the in-situ stress, the depth below the surface and opening geometry. In addition to those parameters, if underground mining is conducted near the slope surface, the influence of slope surface should be taken into account during any mining activities. Consequently, stability analysis has been conducted for three different conditions including the evaluation on the strength of rock mass in the sloping surface, assessment on the stability of stope mining near the slope surface, and instability of stope in the near-ground region in various mine condition. The preliminary results show the instability of rock mass near to slope surface is more severe than that of the rock mass far from the slope surface, therefore large instabilities of rock mass near the slope surface are experienced. In addition, the occurrence of failure zones of stope mining in the near-ground region under slope surface become more pronounced in weaker geological condition and higher stress ratio. All the investigations for these analyses are conducted by means of 3D finite difference software using FLAC^3D,.