The absence of a key stratum during overburden rock movement is crucial to the mining pressure of fully mechanized coal mining faces. Using physical and numerical simulations, the 21304 mechanized mining in Daliuta and Huojitu coal mining faces 1−2 appeared twice during a pressure frame accident analysis. The results indicate that a lack of key overlying strata is crucial to the mining of lower coal seams, particularly for the upper sections of a single key stratum of coal. When the key stratum of the upper coal seam is absent, a stable masonry structure is formed after mining. It is easy to form stable stacked strata at the bottom of a coal seam. When developing gullies in deep terrains, the formation of the key stratum will be an upper rock fracture affected by the impact, resulting in a partial absence of the key stratum. When the key stratum is absent, the mining of upslope working faces and the probability of dynamic strata pressure increase with the overburden on the working face and mining of downslope faces. The face mine pressure development laws on the upper and lower coal seam mining were similar, mainly manifesting as “slope section >valley bottom section >back slope section.”

A mechanical model of a hard roof was built to analyze the pressure relief roof cutting (RCPR) process for gob-side entry retaining (GER) and identify the critical stage of roadway stability control during RCPR. Based on the mechanical analysis of key parameters of automatic roadway with RCPR, the FLAC3D software was adopted to conduct a numerical simulation to investigate the influence law of height and angle of RCPR, to analyze the trend of variations in the vertical displacement of roadway surrounding rock stress and the roof under different conditions, and to verify that the optimal roof cutting height and seam cutting angle of the 12201 working face of Halagou Coal mine are 6 m and 20°, respectively. The effect of automatic roadway with RCPR has been well implemented through conducting the bidirectional cumulative blasting test on site. To impose effective roadway surrounding rock controlling measures on Halagou Coal mine in RCPR of hard, coal-bearing roof structures at a shallow mining depth, constant resistance large deformation anchor cables, in combination with a single hydraulic prop, joist steel 11#, and steel mesh reinforcement, could provide active surrounding rock support. In addition to the active support, surrounding rock control could be strengthened using grouting bolts. Based on the result, the stress in the roadway coal side and the vertical displacement of the roof can be reduced through increasing the roof cutting height, contributing to the stability of the roadway. Increasing of the roof cutting angle will lead to the increasing of stress in the coal side of the roadway and the increasing of roof displacement with a maximum angle of 20°. Meanwhile, the peak of stress concentrating on both sides of the extreme angle is decreased. Thus, increasing the cutting roof angle at random can be unfavorable to the management of roadway roof. To develop RCPR GER, roadway surrounding rock requires greater support when the mine face passes through a cutting slot. After industrial trials, these measures are proved to be effective in controlling surrounding rock movement and developing GER.

Recent years have seen the widespread use of a new gob-side entry retaining technology, namely, automatic roadway forming based on roof cutting and pressure relief. However, because of the complex geological conditions, stability control methods for the surrounding rock remain unexplored. In this paper, through theoretical analysis, field measurement, and numerical simulation, the stability control of a roadway surrounding rock under roof-cutting and pressure-relief conditions is studied. The key stage in the steady-state control of this type of rock is determined by establishing a mechanical model of the hard roof in the process of automatic roadway formation. The results show that the roof-cutting and pressure-relief technology outperforms the conventional mining technology in terms of surface crack development and subsidence. The roadway roof movement can be divided into three stages: a direct roof-caving activity period, a basic roof-breaking activity period, and a roof-stabilizing period. The stress above the original roadway is gradually transferred to the adjacent working face, and a stress concentration is formed on the working face 6 m away from the roadway retaining section. In this scenario, the roadway is in a stress-reducing area, which ensures its safety. Based on the research results, we suggest adding a constant resistance and large deformation anchor cable near the cutting seam side for active support. A single-hydraulic prop + I-beam + steel mesh can support the working face, and a grouting bolt support can help reinforce the broken and loose surrounding rocks at the gangue-retaining side of the roadway. Thus, the movement of the surrounding rock can be effectively controlled. An industrial test shows that the effect of retaining roadway is evidently improved.