Study on overlying strata movement patterns and mechanisms in super-large mining height stopes

Aiming at the problem of strong mining pressure in the near shallow buried and super-large mining height face, and considering the first 108 working faces in Jinjitan Coal Mine as the engineering background, the movement pattern and pressure distribution characteristics of the overlying rock layer on the 8.2 m fully mechanized mining face were analyzed from the perspective of theoretical analysis, field monitoring data, and numerical simulation. The results of the spatial structure mechanics model and FLAC^3D numerical model of the mining face with a super-large mining height established in this study, which indicated that the mining operation of the mining face with a super-large mining height experienced rock dynamic load pressure and large-small periodic pressure phenomena. The fracture of the lower keystone beam leads to a small pressure cycle, and a large pressure cycle occurs when both the upper and lower keystone beams are fractured. Generally, the step distance during the size cycle is about twice the normal cycle. The site monitoring data shows that the initial incoming pressure step is 102 m and the periodic incoming pressure step is about 28.7 m, which is consistent with the theoretical value. When the working surface advances slowly, the dynamic load factor is smaller, and the incoming pressure step and duration are shorter, and vice versa. The research results are of important reference significance for mine pressure law and disaster prevention in similar conditions.