Formation and evolution mechanism of arc triangle structure at the end of fully mechanized mining face

This paper takes the 223102 fully-mechanized coal mining face of Hanjiawan Coal Mine as the engineering background, focusing on the prevention and control of disasters caused by the arc-triangular hanging roof at the working face end. By establishing an elastic beam mechanical model, a theoretical calculation formula for the ultimate span of the end hanging roof was derived, and physical similarity simulation experiments were used to analyze the distribution of the surrounding rock stress field and the evolution law of roof breakage during the mining process. The research shows that the theoretical calculated values for the ultimate span of the end hanging roof are 24.9 m in the strike direction and 12.45 m in the dip direction, which are in good agreement with field measured data and physical simulation results; sensitivity analysis indicates that the influence of roof load, main roof thickness, and tensile strength on the ultimate span decreases sequentially; the overburden failure exhibits an "O-X" type pattern, and the arc-triangular plate structure formed by higher rock layers is the main cause of strong dynamic load impact.