Abstract: Open-pit rocky high slope landslide brings a major threat to production safety,and seriously affects the economic benefits of mine.For a mine that has had a landslide,in order to avoid from similar accidents,a landslide risk assessment should be made on the whole mine.Based on the study of the mechanism of landslide in Zone C of Bayan Obo's main East mine,comprehensive geophysical prospecting,including seismic method,geophysical radar method and high density resistivity method,was made in non-landslide and not strengthened areas.On the basis of the results of the comprehensive geophysical prospecting,five indicators such as moisture content,mode of fault combination,etc.which influence the stability of slope are selected.Judgment matrix is made by comparing arbitrary two factors of five.After transforming the judgment matrix,weight matrix of these factors is obtained.Coupled with the experience and parameter sensitivity analysis,an evaluation set including big,medium and small level of risks is constructed for these factors,and each factor's membership degree to each evaluation level is calculated.Taking a cross-section for example,the gray fuzzy matrix and the weight matrix are constructed and a gray fuzzy comprehensive evaluation is conducted to determine the landslide risk of the cross-section.

Key words: Comprehensive geophysical prospecting, Landslide, Gray fuzzy comprehensive assessment