Engineering practice and theoretical progress of top-coal caving mining technology in China

This paper summarizes the engineering practice of longwall top-coal caving (LTCC) in China in the past 35 years,which can be divided into three stages:exploratory stage,promotes application stage,expands stage,mature and output stage. LTCC has become a representative technology and achievement of Chinese coal mining practice around the world. The theoretical research and progress of LTCC are summarized as the stage of reference,the stage of explora- tion and the stage of innovation. Innovative theoretical achievements in the field of top-coal drawing law are introduced and some directions of the theoretical research of LTCC in the stage of innovation are proposed. For example:the frac- ture mechanism of top-coal,the drawing law of the loose top-coal,the relationship between the support and the sur- rounding rock,the strata movement law,the supporting mechanism of full coal roadway,basic economics of LTCC,etc. In-depth theoretical research can further guide the improvement of LTCC technology and expand its application.