Discussion on the stability evaluation standard of a rock slope in a noncoal open-pit mine

As an important way to obtain mineral resources, open-pit mining has accounted for about 77% of the total production of the mined iron ore, and about 52% of the total production of non-ferrous ore, indicating huge development potential. With the continuous development of open-pit mines to deep and large-scale directions, the height of mine slopes is constantly increasing and the maximum height has exceeded kilometers. Slope instability disaster is a major problem faced by open-pit mines, and the evaluation and analysis of the stability of mine slopes are of great importance. However, in the stability evaluation and analysis of rock slopes in many open-pit mines, the engineering scale is ignored, the value of design safety factor is too conservative, and the evaluation index is single, rendering it difficult to consider the economy and safety of mine slope evaluation and resulting in the waste of resources and frequent accidents. In this paper, rock slopes were divided into three scales according to the production process characteristics of open-pit mines: (1) overall slope, (2) inter-ramp slope, and (3) bench slope. Moreover, the control elements and failure modes of the slopes were analyzed. Combined with the design safety factor value of the civil-engineering slope standards and specifications of a non-coal open-pit mine slope, the design safety factor requirements of non-coal open-pit mine slopes at home and abroad were discussed, then six suggestions were put forward. Comprehensively taking service years and the improved scheme of design safety factor in slope scale into consideration, the instability probability were introduced to extend the design standard of slope stability evaluation in different scales, which can effectively improve the rationality and scientificity of the rock slope stability evaluation in non-coal open-pit mines, further improving the mining slope design theory and method.