中文摘要：

某铁矿自露天转入地下开采后,采用无底柱分段崩落法采矿。实际生产中出现了损失贫化大、块度两级分化严重、眉线保持不住等问题,严重影响了矿山正常生产。基于随机介质放矿理论,通过单体及立体放矿试验对矿山的结构参数进行了优化,推荐了最优的结构参数为20 m×18 m×4 m（分段高度×进路间距×崩矿步距）,对于进一步提高回采率、降低贫化率有一定的借鉴价值。

英文摘要：

Non-pillar sub-level caving method has been adopted in a iron ore mine from open-pit to underground mining. The problem of high loss and dilution ratio,polarising the minerals size distribution,failure of brow line when mining production are seriously affected the normal production of the mine.Based on the stochastic theory of ore-drawing,and the structure parameters are optimized by single and three-dimensional ore drawing model,the optimal structure parameters is recommended,which are sublevel height is 20 m,drift interval is 18 m and caving step distance is 4 m,so as to provide some reliable basis for improving the recovery rate and decreasing the dilution rate of the mine.