Through simulation experiments, it was found that when the "cantilever beam" structure of the key layer 1 breaks and moves, it presents three different movement patterns due to the different falling shapes of the collapsed rock blocks behind and the different fracture block sizes of the blocks.
(1) The broken blocks of the "cantilever beam" of the key layer rotate directly, but due to the large rotation angle, they cannot form an articulated structure and eventually collapse directly in the goaf, and the key layer forms a new "cantilever beam" structure.
(2) After the broken blocks of the cantilever beam of the key layer rotate at a small angle, they touch the broken blocks behind and stop rotating, and temporarily form a stable equilibrium structure. After the working face continues to mine for a distance, the blocks rotate in the opposite direction and collapse, and finally form a new "cantilever beam" structure.
(3) After the broken block of the key layer cantilever beam rotates a small angle, it touches the broken block behind and stops rotating, forming a stable hinged structure that moves forward continuously with the mining of the working face. However, after several broken hinges, it eventually collapses and forms a new "cantilever beam" structure.