The approach of searching the most dangerous slip surface is always a hot area for research. However

the other secondary potential slip surfaces

which do not meet the requirement of safety

should also receive attentions. The shear strength parameters of the whole area are reduced in the conventional strength reduction method; but only the minimum safety factor and the most dangerous slip surface can be obtained through this approach. An analysis method of slope multi-slip surfaces

which is based on local strength reduction method

is proposed. Firstly

the safety factor of each element is defined and calculated; different element sets with the safety factors falling in various specific scopes are found out automatically. And then the shear strength parameters of those element sets are reduced respectively; the slip surfaces corresponding to different safety factors are located. The feasibility of this approach is verified through a slope with single step and a slope with double steps. The results show that the depth of the secondary slip surface and the slip area enlarge with the increase of the safety factor of the slope. At last

this method is applied to stability analysis of a slope located at the entrance of a tunnel; and the multi-slip surfaces acquired from the proposed method can agree well with the field data.