Physical and mechanical parameters of rock and soil are uncertain in slope stability analysis.Interval variables are adopted to denote the uncertain parameters in engineering.The interval finite element method

which is combined by interval mathematics and finite element method

is used for uncertain analysis of slope stability.On the basis of the traditional certain finite element program

the interval finite element program aiming at a known potential sliding surface is designed to calculate the displacement

stress and strain interval of a slope.Furthermore

the safety factor interval is also obtained according to the definition of shear stress failure criteria.It is verified that this method is feasible and effective through the project example and comparing with the calculation results obtained by traditional Bishop method.A further discussion on the influence of variability of the geotechnical parameters on slope safety factor is performed.Results show that unit weight

cohesion and internal friction angle interval have significant effects on the safety factor interval.