通过对凤凰山矿综采下分层工作面在回采过程中冒顶原因的分析研究，探讨了下分层工作面的顶板控制措施。
Through analyzing the reasons of fall of ground during the actual mining on the combined mining lower layered face of Fenghuangshan Coal Mine , the measures of controling the roof are approached .
凤凰山下