The pressure relief of coal pillars in close-distance multi-coal seam goaf is a complex engineering problem with the characteristics of “dynamic mine pressure”. Hence, this paper studies such problems. First, the influence factors of the coal pillar in the goaf on the mine pressure of the mining face of the lower coal seam under this condition were theoretically analyzed, and it was concluded that vertical stress is the most important element, followed by horizontal stress. Next, a physical similarity simulation experiment was designed to study the stress distribution law of the coal pillar floor in the goaf before and after pressure release and the damage depth. Finally, a technology and monitoring method for coal pillar blasting pressure alleviation in goaf were introduced and implemented in engineering practice. After the pressure is alleviated, the surrounding rock stress of the lower coal seam mining face is redistributed, and the vertical stress is decreased by 20%. The adjacent rock’s deformation is improved. This technology’s cost and safety advantages are extraordinary and helpful for mining coal seams over close distances.

In order to address the issue of slow excavation speed caused by various factors affecting the stability of the roof in the excavation face and the unreasonable distance of the unsupported roof, a mechanical model of the roof in the excavation face area is established. This model is based on the superposition method in the material mechanics. The immediate roof deflection curve equation and the maximum unsupported roof distance discriminant formula of the heading head are derived. The allowable deflection is used as the discriminant method of the maximum unsupported roof distance. The calculation method of the key parameters in the formula is obtained and compared with the existing maximum unsupported roof distance calculation formula. Using the single-variable sensitivity analysis method and the bivariate interaction analysis method, we determine the key factors affecting the deformation of the roof in the excavation face and their interaction relationships. The results indicate that among the 10 factors affecting the deformation of the roof in the temporary support area of the excavation face, there are 3 key factors. Under unchanged geological and mechanical conditions, the deformation of the roof primarily depends on the length of the temporary support area and the temporary support load. To provide a practical example, we calculate the maximum unsupported roof distance of 30304 tailgate in the Yanghuopan Coal Mine to be 3.4 m. Numerical simulation and field monitoring results confirm that the deformation of the roof in the excavation face is minimal, and the stability of the rock is good.

In order to study the pressure changes and support failure in mining face under concentrated coal pillar in shallow coal seam, the concentrated coal pillar in 30105 working face of Nan Liang Coal Mine was selected as the research object. In this study, the mechanism of dynamic mine pressure in mining face under concentrated coal pillar was investigated through multiple simulation experiments, numerical simulations, and theoretical analysis. The results of similar simulation experiment indicate that the dynamic mine pressure occurred at 25 m under the concentrated coal pillar and 7 m beyond the coal pillar. The strata roof was observed with sliding down, resulting in collapse and severe fractures commonly seen in rock column. The overlying strata caused the overall subsidence and collapse synchronously, resulting in the sudden increase of the resistance of the support in the working face, and the dynamic load coefficients reach 3.4 and 3.5. The theoretical analysis indicates that the two hard strata in the overlying strata of 3⁻¹ coal meet the theoretical criterion of the combined key strata with the concentrated coal pillar of 2⁻² coal in the weak interlayer of the combined key strata. The combined key strata bear the load of the whole overlying strata. The sliding instability featured with the rock column‐type fracture located in the combined key strata is considered as the primary trigger of the abnormal resistance of the support and the dynamic mine pressure in the mining face under the concentrated coal pillar. The dynamic pressure model of “combination key strata—immediate roof‐support” was established, along with the dynamic load coefficient calculation related to the rock column‐type fracture and instability. The characteristics of dynamic load coefficient of the rock column‐type fracture and instability under different overlying rock structure conditions were analyzed, providing references and insights into mining under similar geographic conditions.

Here, we analyze the instability characteristics of the overlying strata structure that characterize shallow-depth seams under insufficient goaf in Yushenfu mining area. To simulate the No. 20107 longwall interval working face situated in Nanliang Coal Mine, physical simulation, an acoustic emission (AE) monitoring system, a stress acquisition system and a total station were used. The results indicate that during interval goaf formation, which is correlated with mining, the immediate roof collapses, and the main roof strata remains stable. Gradually, the stress that acts on the temporary coal pillar (TCP) gradually exhibits the ‘uniform increase–accelerated increase catastrophe instability’ change characteristics. Due to the concentrated load of the overlying strata, the bearing capacity of the TCP gradually deteriorates until the catastrophic instability occurs, and the unstable roof strata forms a ‘W-shaped voussoir beam’ structure. The research results provide evidence for the strata control that is associated with shallow-seam mining.

The thin spray-on liner is an inorganic polymer product that has been widely used to support mine perimeter rock roadways, but it is mainly used in metallic hard rock roadways with high rock strength and is less used in roadways affected by roadway corrosion and weathering in shallowly buried coal seams. Therefore, this study studies the thin spray-on liner support technology under such geological conditions. First, the causes of anchor support failure in this condition are analyzed, and it is concluded that alkaline ionized water corrodes the anchor rods, and chloride ions in the water play a role in accelerating the degree of anchor rod corrosion. Next, microscopic testing was used to determine the content of weathering and swelling minerals contained in the roof rock and the development of tectonic fissures. Third, the loosening circle of the surrounding rock is theoretically calculated and used as a basis to design the anchor mesh rope support parameters for the roadway. Finally, the construction process of a thin spray-on liner anticorrosion and antiweathering support technology is introduced. This technology improves the anchor force environment of anchor rods while incorporating anchor rods (ropes)—rock—metal mesh into the support system to play a coupling support role. On-site monitoring is performed to derive the optimum thickness of the spraying layer in different environments. At the same time, the deformation of the roadway surrounding rock and the anchor force can be improved to meet the requirements of anticorrosion and antiweathering and tighten the roadway surrounding rock. Compared with concrete support technology, the economic and environmental benefits of this support technology are apparent, and it helps to promote the application in shallowly buried coal seam mines.