煤层顶板覆岩一般以页岩、砂岩、灰岩等沉积岩为主，其物理力学性质差异很大。

The overlying strata of the coal bed roof are dominated by sedimentary rocks such as shale, sand stone and limestone, whose physical and mechanic properties differ greatly.

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煤层顶板覆岩一般以页岩、砂岩、灰岩等沉积岩为主，其物理力学性质差异很大。

The overlying strata of the coal bed roof are dominated by sedimentary rocks such as shale, sand stone and limestone, whose physical and mechanic properties differ greatly.

youdao