Physical simulation is one of the effective methods to study mining problems, but the selection and proportion of simulation materials are greatly affected by the regional environment. This paper is based on a multilevel orthogonal design test scheme using sand, lime, and gypsum as the materials in the Shangwan coal mine in the Shendong coalfield, with the sand to cement ratio, paste to ash ratio, and maintenance days as variables. The effect of the polar difference method on the strength and density of gypsum was used as a reference for physical simulation in the Shendong coalfield. The sensitivity analysis of each factor was carried out by the polar difference method, and the influencing factors on density were, in descending order, sand to mortar ratio, mortar to ash ratio, and the number of maintenance days; the influencing factors on strength were, in descending order, mortar to ash ratio, maintenance days, and sand to mortar ratio. The sand cement ratio was negatively correlated with strength and density, the paste to ash ratio was positively correlated with strength and density, and the number of maintenance days was positively correlated with strength and negatively correlated with density. The multivariate non-linear regression analysis of sand to cement ratio and paste to ash ratio identified similar material proportioning test equations for the Shendong coalfield, which can improve the accuracy of physical simulation and be used to guide physical simulation experiments in the Shendong coalfield.

With the gradual depletion of easily exploitable coal resources in the shallow crust, deep mining under complex geological conditions will become the new normal. Deep mining causes complex stress disturbances to the overlying strata. In order to study the deformation and fracture evolution characteristics of overburden under deep mining conditions, this paper studies the first mining face of a mine in Ordos, Asia, and combines a variety of research methods such as similarity simulation, fractal geometry and percolation theory to carry out research. First, the distribution morphology and development process of overburden mining cracks were studied through similarity simulation experiments, and the law of changes in the horizontal and vertical fracture density with the distance from the working face was obtained; secondly, the scale effect of the cracks was studied using fractal geometry theory, revealing the distribution law of cracks at different scales; finally, the development characteristics of the largest group of crack percolation were discussed, and the functional relationship between the percolation probability and the fractal dimension was given. The research results show that: the transverse and longitudinal fracture ratio of the overburden increases first, then decreases, and finally increases again as the working face advances. The mining cracks are generally distributed in an “M” shape with high ends and low middle; the change of fractal dimension is affected by factors such as the distribution, density, arrangement, connectivity and generation mechanism of the fracture network. The fractal dimension has two abrupt decrease points as the working face advances. According to the abrupt decrease points, the evolution of the fractal dimension can be divided into three stages; the percolation probability increases as the working face advances, and three growth rates appear in this process. According to the growth rate, the evolution of the percolation probability can be divided into three stages; the comparison of the changes in fractal dimension and percolation probability shows that the change nodes of the three stages are the same, and the fitting shows that the fractal dimension and the percolation probability have a good correlation. The research results can provide certain theoretical support for the zoning analysis and evaluation of mining damage in overburden strata under deep mining conditions.

Existing coal filling mining technologies face significant challenges of controlled surface subsidence, efficient utilization of waste rock in coal mines, and a shortage of adequate filling materials. This study introduces an innovative cut-and-fill mining method designed to strategically partition the goaf into cutting and filling zones. In the cutting zone, in situ filling materials are employed to construct waste rock column supports adjacent to the filling zone, thereby achieving controlled surface subsidence. This approach is integrated with long-wall mining operations and implemented using advanced, comprehensive equipment. FLAC3D simulations were conducted to investigate the patterns of stress distribution, surface deformation, and plastic zone formation within the mining field. With the implementation of the cut-and-fill mining balance, key observations include a reduction in maximum principal stress near the center of the goaf, an increasing trend in minimum principal stress, regular displacement distributions, and intact plastic zones positioned vertically away from the stope and horizontally close to the center of the stope. Compared to traditional caving methods, the cut-and-fill technique significantly reduces maximum vertical displacement, by nearly 95%, and maximum horizontal displacement, by approximately 90%. Additionally, it minimizes energy accumulation, lowers overall energy release, and prolongs the release period. Importantly, this method facilitates the resourceful utilization of approximately 800 million tons of waste rock, potentially leading to an estimated reduction of 500 million tons in CO₂ emissions. By achieving a balance of three effects—harmonizing coal extraction and filling capacity, aligning the supply and demand of filling materials, and optimizing the balance between filling costs and mining benefits—this method provides a sustainable and eco-friendly solution for the coal mining industry. The findings of this study are crucial for guiding the industry towards more environmentally responsible practices.

In high-intensity mining operations in western China, shallow burial depths and rapid advancement rates induce rapid surface responses, significant deformation, and pronounced crack development. This study comprehensively evaluates these effects through full-process rock movement monitoring at the Jinjie coal mine, focusing on subsidence coefficients, mining coefficients, and inflection point trajectories. Results indicate that weak stability of the overlying strata in the shallow-buried working faces led to substantial surface subsidence, with a subsidence coefficient of 0.87, exceeding typical values (0.6–0.7) for conventional mining. The inflection point at the open-off cut followed a monotonic L-shaped trajectory, migrating laterally up to 4.7 times the mining height (15 m), while the inflection point near the roadway stabilized at 5.6–7.5 times the mining height (18–24 m) after two fluctuations. A significant contrast was observed in the horizontal movement coefficient between the goaf area (0.21–0.47) and the unmined area (1.59–2.38). Surface cracks exhibited an O-shaped ring distribution, synchronizing with periodic weighting intervals of 12–14 m; the pressure coefficient was approximately 1.73. Despite pronounced crack development, self-healing mechanisms reduced environmental risks. Full surface subsidence was achieved after the working face had advanced 320 m, a distance approximately equal to 1.24 times the working face length and 3.5 times the burial depth, with the basin areas occupying 48% of the total. Surface stabilization was achieved within 70 days (less than the ratio of burial depth to 100 m), underscoring the necessity of proactive measures such as crack filling to prevent air leakage and water inrush during rapid advancement (20 m/day).

With the increase in mining intensity and scale, the damage to groundwater resources and surface ecology caused by coal mining has become the main problem facing coal development. Coal mining can cause a redistribution of stress field and stress concentration in local areas of overlying rock, resulting in varying degrees of movement and damage to the overlying rock. Quantitative analysis of the degree of migration and damage in different areas of overlying rock and zoning control is crucial for achieving loss reduction and green mining. In this paper, the overburden damage is divided into regions according to the different causes of formation, regional characteristics of severity, and other factors, and the specific calculation method is given. UDEC7.0 numerical simulation software is used to simulate the overlying rock damage, and the best mining parameters are provided through the area changes in different zones. The research conclusions are as follows: according to the different damage states of overburden rock, the damage of overburden rock can be divided into four parts: I, caving fracture zone, II, fracture development zone, III, sliding failure zone, and IV, slight failure zone. In the four zones, the damage in zones II and IV is relatively light. During the mining process, attention should be given to controlling the development of Zone I to prevent it from abnormally enlarging; for Zone II, hydraulic fracturing can be used when there is a thick, hard key layer that poses a water inrush risk; for Zone III, the focus should be on preventing surface step fractures caused by it. For example, when a thick, hard key layer is present in Zone II, hydraulic fracturing can be applied to avoid large area hanging roofs and severe rock pressure. When the mining height is low, it mainly affects the proportion of regions I and III. With the increase in mining height, the main affected region becomes the II region. The larger the mining height is, the larger the proportion of the II region. With the increase in propulsion speed, the impact range on the surface increases, but the area with severe damage is relatively reduced. With the increase in mining width, the proportion of relatively seriously damaged areas increased. On-site measurements have shown that when the speeds of 120,401 and 22,207 working faces are slow, the rock layer pressure shows a dense state, the overburden fracture is more fully developed, and the area proportion of I and II zones is increased, which reflects the phenomenon of dense surface fracture development on the surface. When the advancing speed is large, the area proportions of zones III and IV increase, and the damage scope decreases. The on-site testing verified the conclusions drawn from theoretical analysis and numerical simulation, which can guide other mines under similar conditions to achieve safe and green production.