When using numerical simulation methods to solve the stability of slope

the strength reduction method is in common use. But this method is not validated and generalized because there are many factors which affect the precision of results. Using the fast Lagrangian analysis of continua (FLAC) according to the comparison of results we can find out the influences of boundary range and density of the grid in the analysis of slope stability. Especially we get rid of the bondage that is the boundary range should be large enough which is the modeling principle. The results prove the reliability of the conclusions.