【摘要】 对于在露天矿底部与地下矿顶部设置联合采矿层的露天－地下联合开采，依据露天－地下联合采矿的综合成本不超过地下开采成本原则，推导出露天开采极限深度计算公式，分析表明，设置联合采矿层的露天开采深度大于按传统方法确定的露天开采极限深度。更多还原

【Abstract】 For the opencast-underground combined mining of the layer between the open-pit bottom andhe undergrround mine top, a formula for calculating the depth limit of opencasting mining is deduced accordingto the principle that the gross cost of opencast--underground combined mining should not exceed that of underground mining. The analysis has shown that the depth of OPencast mining for the combined mining is greaterthan that determined by the conventional method.更多还原