Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

Generally it is likely that rock mass properties are expressed not by a mean value but by values with variation due to its characteristic \'uncertainty\'. So this study reports the effect of the uncertainty of rock mass properties on the stability of an underground structure. The radius of the fractured zone in terms of the variation of rock mass properties is examined using a Monte-Carlo simulation, in which the internal friction angle and uni-axial compressive strength of the jointed rock masses are expressed by the random variables having a normal distribution function with a certain mean and a standard deviation. Also, stability analysis using Monte-Carlo simulation is performed in order to investigate the influence of the variation of GSI value on the stability of the excavation, when Hoek-Brown failure criterion is adopted. From the results of this study, it is observed that the variation of rock mass properties significantly affects the radius of the yield zone and the stability of the underground structure due to the excavation. In conclusion, the method of probabilistic analysis must be used for the design of underground structures in the jointed rock masses having large variations of rock mass properties.