• The false top is the existence pole exchanges weak caving rock stratum between the coal seam and direct top. In the coal mining, it may often be happened.

    煤层直接之间存在极易垮落软弱岩层井下采煤工作面回采时,常常遇到。

    youdao

  • The false top is the existence pole exchanges weak caving rock stratum between the coal seam and direct top. In the coal mining, it may often be happened.

    煤层直接之间存在极易垮落软弱岩层井下采煤工作面回采时,常常遇到。

    youdao

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