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.

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;

If you are impatient and want a quick preview of how simple a Seam application is, you can have a look at the hello world example described lower in this article.