the coal wall or roof of working face is perforated, and a hydraulic expansible anchor stock is inserted into the hole.
本发明涉及煤矿井下开采工艺,进一步讲是回采工作面防止片帮冒顶的一种方法。
the rapid development of stock market give a big challenge to monetary policy and whether monetary policy should anchor stock price has been one of the most advanced issues.