Overlying strata spatial structures of longwall formed by working faces that is mined and four sides are substance coal are named "o" letter type spatial structures.
我们把一面采空(四周为实体煤)形成的采场覆岩空间结构称为“O”型空间结构。
Overlying strata spatial structures of longwall formed by working faces that is mined and four sides are substance coal are named "o" letter type spatial structures.
我们把一面采空(四周为实体煤)形成的采场覆岩空间结构称为“O”型空间结构。
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