ABSTRACT
L. A. Fuzzy set theory has been proposed by L. A. Zadeh and it has been known as appropriate approach for dealing with uncertainty mainly caused by incomplete information. Consequently, fuzzy set theory has been employed in many slope stability analyses. The uncertainties caused by limited or incomplete information cannot be handled satisfactorily in the probability theory and the fuzzy set is more appropriate. The Monte Carlo simulation is the most complete method of the probabilistic analysis since all the random variables are represented by their statistical parameters and probability density function. In addition, the complete information is employed to evaluate performance function in Monte Carlo simulation. In most rock slope stability analyses, the friction angle of discontinuity is considered as uncertain parameters. Monte Carlo simulation, too small value of friction angle could be generated and used in factor of safety calculation. This could cause serious error in the evaluation of the probability of failure.
