无底柱分段崩落法的分段高度、进路间距和崩矿步距的不同组合，严重影响放矿损失贫化指标，从而影响了矿山的经济效益。本文运用未确知测度理论和层次分析法，建立单位精矿盈利的评价模型。评价模型综合考虑了影响单位精矿盈利的各种因素，如贫化率、回收率、混入废石的品位和尾矿品位等。利用实测数据建立单指标未确知测度矩阵，然后通过层次分析法（AHP）计算出各指标因素的权重，依照置信度识别准则对单位精矿盈利进行评级，进而对崩矿步距进行优选。实例分析结果显示，大红山铁矿440分层崩矿步距为4.8m时，单位精矿盈利为优，从而确定为最优崩矿步距。

Different combinations of segment height, route spacing and breaking interval have a significant effect on the indicators of the depleted ore loss, thus affecting the mining economic benefits. In this paper, the uncertainty measurement theory and the AHP(Analytical Hierarchy Process) are used to establish an evaluation model of the unit concentrate earnings. The evaluation model takes account of various factors that affect the unit concentrate earnings, such as the dilution rate, the recovery rate, the grade of the rock mixed with waste rock and the grade of tailings. The measured data are used to create a single index unascertained measurement matrix, then calculate the weight of each index by the AHP and evaluate the unit concentrate earnings according to the credible degree recognition criteria, thus determine the preferred caving step. In examples, the unit concentrate earnings are optimal when the breaking interval is 4.8m for the 440 stratified of Dahongshan Iron, and the step for the optimal breaking interval is determined.