根据作者对大同矿区直接顶板控制的研究和了解，提出了一种简单易行的直接顶分类方法。
According to the studying and acquainting with the direct roof control of Datong mining area, this paper offers a kind of simple and workable classification for direct roofs.
首次将顶煤的分类与直接顶、老顶的分类结果相结合，弥补了原有顶板分类方案不适合放顶煤采场的不足。
Combine top-coal classification with roof classification for the first time, which make up the inadequate of former classification program.
首次将顶煤的分类与直接顶、老顶的分类结果相结合，弥补了原有顶板分类方案不适合放顶煤采场的不足。
Combine top-coal classification with roof classification for the first time, which make up the inadequate of former classification program.
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