Abstract: In order to explore the deformation mechanism and influencing factors of the short cantilever beam under the technology of pillarless mining with gob-side entry retaining by roof cutting and pressure relief, the roof structure and motion process are analyzed, and the mechanical model of the short cantilever beam roof is established. Based on the principle of function, a calculation formula for the deformation of the short cantilever beam roof in the three stages of the early, middle and late stages is derived. The influencing factors and sensitivity of the short cantilever beam roof in each deformation stage are discussed, and the corresponding control ideas are put forward according to the main control factors in each deformation stage. The results show that the deformation of the short cantilever beam roof in the early stage is small. At this stage, the elastic modulus of basic roof, the strength of support in roadway and roof, and the height of short cantilever beam have a significant influence on it. In the medium-term stage, the deformation is large, and is significantly affected by the bulking coefficient, the modulus of the short cantilever beam roof and the width of the roadway. The roof is in a relatively stable state at the later stage, and the deformation is basically no longer changed. A countermeasure of phased main control factors, namely timely high-strength support in roadway + roof cutting plan optimization was proposed for the S12012 working face of Ningtiaota coal mine. Good effect of field application was verified.

Key words: roof cutting and pressure relief, pillarless mining with gob-side entry retaining, roof cutting short cantilever beam, roof deformation, influence factor, control measures