Coalface of Daizhuang Coalmine, the authors believe that the roof in lower seam will form the "block-bulk-beam" structure easy to fall after the mining of top ultra-close seam.

通过对岱庄煤矿4300采区工作面的顶板结构分析，得出了上部极近距离煤层开采后，下部煤层顶板形成极易漏冒的“块体-散体-梁”结构。

Today during the mining process in contiguous seams, there are many factors leading to hidden danger, such as: the top board being tortured during the exploitation of the lower seam;

目前，我国矿山在极近距煤层开采过程中，下部煤层开采时，顶板遭受损伤，工作面及巷道顶板易于出现冒顶、漏顶现象，严重时造成支架埋压；