Abstract: There are many factors that be influence the stability of soil slopes and these factors have different degrees of influence. This paper presents a case history of the stability evaluation of a loess soil slope in Kelan, Shanxi Province. The stability analysis is performed using the improved orthogonal method. This improved method is based on the conventional orthogonal design method and is combined with the grey correlation method. The analytical model was established with software ADINA and the model sensitivity to the parameters, such as, slope height, slope angle, unit weight, cohesion, internal friction angle and surcharge at the crest, are studied. The results indicate that, the strength parameters of the slope, slope ratio and the slope height have the significant impact on the safety of the slope. The surcharge and the unit weight of the soil has less impact. The appropriate slope stability design is then recommended: the reliable strength parameters should be selected in the design. The slope ratio and slope height should also be considered in the design.

Key words:  Loess Slopes, Orthogonal Design Method, Grey Correlation Method, Improved Orthogonal Method, Sensitivity