Study on Target Reliability of Mine Rock Slopes by Grey Fixed Weight Clustering and Analogy Method—Case Study of the Jinbao Iron Mine

The target reliability of mine rock slopes must be scientifically determined, which can fully reflect the safety level of slope stability and plays an essential role in establishing slope reliability design guidelines. Since the design guidelines based on reliability methods have not been established for mine rock slopes, the suggested target reliability values are proposed based on the grey fixed weight clustering and analogy method. Firstly, a new evaluation method of slope safety grade is proposed by considering more influencing factors of slopes. Secondly, the grey fixed weight clustering is used to quantitatively processes the slope reliability data, and the slope safety grade is judged. Then, the target reliability of each grade is obtained by the analogy method. Finally, the equal difference method is applied to set the threshold of allowable failure probability for the minimum service life of slopes, and the reliability of other service life is processed by linear interpolation. The results show that, the target reliability of the maximum service life for grade I, II, III ductile failure is 3.25, 2.75, 2.25, and brittle failure is 3.75, 3.25, 2.75, respectively. the allowable failure probability of the minimum service life for each grade shows that the ductile failure is 1%, 3%, 5% and brittle failure is 0.5%, 1%, 3%, respectively. In addition, the suggested values of Inter-ramp and Bench slopes are also improved, and a case study is conducted in the Jinbao iron mine to illustrate the feasibility of the method and results in this paper.