Advances on longwall fully-mechanized top-coal caving mining technology in China during past 40 years:theory, equipment and approach

Fully-mechanized top-coal caving technology is one of the main methods for mining thick and extra thick coal seams in China. Since it was introduced into China for nearly 40 years, the theory and technology practice of top-coal caving mining in China has made great progress. This paper systematically reviews and summarizes the landmark achievements in the field of top coal caving technology in China. Combined with the technical characteristics of fully-mechanized top-coal caving face, the theoretical evolution logic and the new concept of resource exploitation, the development process is divided into three stages: initial test, mature development and intelligent unmanned mining. This paper mainly summarizes the development of fully mechanized top coal caving technology in China from four core aspects: the relationship between support and surrounding rock, roof （coal） structure and stability, top coal fragmentation, migration and release law, as well as the development of "three machines" equipment in fully mechanized top coal caving face The basic course of Chinese scholars' research on this problem; from three aspects of top coal crushing mechanism, top coal caving classification and evaluation in fully mechanized top coal caving stope and the theory of top coal drawing law, the development road of top coal breaking, migration and drawing law in China is shaped; in the research of top coal caving mining technology, it is from the conventional fully mechanized caving technology, the fully mechanized caving technology under special geological conditions and the fully mechanized caving process At the same time, it briefly describes the development process and the latest achievements of the "three machines" equipment. This paper clarifies the development context and research ideas of top coal caving technology in China, and analyzes and discusses the relevant problems of the current top coal caving mining theory and technology development frontier, which provides research basis and thinking enlightenment for the further development of fully mechanized caving technology in China.