Underground tunnel support of soft expansion rock is a main difficulty in mine construction currently.

松软臌胀岩层的井下巷道支护是目前矿山建设中的一个主要难点。

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Underground tunnel support of soft expansion rock is a main difficulty in mine construction currently.

松软臌胀岩层的井下巷道支护是目前矿山建设中的一个主要难点。

youdao