The transition from open pit mining to underground mining is essential for mineral resources to achieve deep excavation. Recently, cemented paste backfill (CPB) has been proposed as a novel technology to achieve open pit backfill (OPB). The proposed method not only eliminates the danger of the open-pit slope but also reduces the disposal of waste tailings. In order to ensure safe mining during the synergetic operation of OPB and underground mining, it is of great significance to improve this technology. In the present study, an open-pit metal mine in Anhui Province was taken as the research object. Then, the safety of underground stope roofs, underground backfill pillars, and open-pit slopes was evaluated during OPB. To this end, numerical simulations were performed and experiments were conducted on a similar physical model. Accordingly, the backfill mechanical parameters were optimized. The obtained results show that backfill height exerts the most significant effect on the safety of roofs and underground backfill pillars, accompanied by small displacements along the vertical direction during the backfill process. Moreover, concentration was observed at the foot of the slope, while the overall structure remained stable with no considerable displacement. The overall safety factors met the safety requirements. Based on the obtained results, the optimal foundation strength, foundation height, backfill strength and backfill height were 4 MPa, 10 m, 1.5 MPa, and 120 m, respectively. Moreover, it was concluded that displacements in the abovementioned three regions tend to be stable when the backfill height exceeds 150 m without damage. The present article provides a certain theoretical and application guideline for OPB practices in similar metal mines and suggests possibilities for cleaner production.

中文翻译：

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尾矿回填露天矿与地下矿床开挖协同作业安全分析

矿产资源实现深部开挖，从露天开采向地下开采的转变是必不可少的。最近，水泥浆回填（CPB）被提出作为实现露天矿回填（OPB）的新技术。所提出的方法不仅消除了露天边坡的危险，而且减少了废尾矿的处置。在OPB与地下开采协同作业过程中，为确保安全开采，对该技术进行改进具有重要意义。本研究以安徽省某露天金属矿山为研究对象。然后，在OPB期间评估了地下采场顶板、地下回填柱和露天边坡的安全性。为此，进行了数值模拟，并在类似的物理模型上进行了实验。因此，优化回填土力学参数。所得结果表明，回填高度对顶板和地下回填柱的安全性影响最为显着，回填过程中沿垂直方向的位移较小。此外，在斜坡脚下观察到集中，而整体结构保持稳定，没有明显的位移。总体安全系数满足安全要求。根据所得结果，最佳地基强度、地基高度、回填强度和回填高度分别为4 MPa、10 m、1.5 MPa和120 m。此外，当回填高度超过 150 m 时，上述三个区域的位移趋于稳定，没有破坏。