Coal is an important resource that has supported China’s economic development. This situation is expected to continue in the immediate future. However, coal mining has also led to serious environmental disasters in some mining areas. Henan Province is one of the 14 large-scale coal bases that are planned by the Chinese state. It is located in the transitional zone between the second and third terrain ladders of China and spans two tectonic units. The geological features and ecological environmental characteristics display wide spatial variations throughout this district, which is an ecologically fragile region of stepped transition type. However, large-scale, extremely intense coal mining activities will inevitably lead to further deterioration of the already fragile ecological and geological (eco-geological) environment, which makes recovery increasingly difficult. Based on the condition of the eco-geological environment and the coal mining industry in the Henan mining area, the mechanisms by which mining-induced damage can occur were analyzed. The characteristics and status of the destruction of ground structures, land resources, water resources, the atmospheric environment, and natural ecology are discussed in this paper. Appropriate mitigation measures are proposed based on the findings. This mainly includes: management practices to prevent and mitigate damage throughout all stages of mining; adoption of mining techniques that will control damage at the source; and, the adoption of appropriate post-mining recovery technologies. The analysis of mining-induced eco-geological environmental damage and mitigation measures is of importance for the prevention of eco-geological disasters, and the promotion of efficient and environmentally sustainable exploitation of coal resources.

There are risks of water burst and sand inrush in the working face of the Northwest Mining Area in China. Based on the 22407 working face of Halagou coal mine, the evolution characteristics and mechanism of a two‐zone failure mode of the overburden strata in shallow buried thick seam mining were thoroughly analysed using physical modelling, theoretical analysis, on‐site observation, and other research methods. A method to calculate the overburden fissure width was also proposed. The analysis results indicated that the evolution of a two‐zone failure mode of the overburden strata mainly includes four stages: gestation, formation, transformation, and stabilization. In the transformation stage, a fracture zone is transformed into a caving zone. The caving zone and fracture zone are separately transferred to the working face direction based on the structure type of key strata of voussoir beam and cantilever beam after the heights of the two zones stabilize, and the “two‐belt” cracks are mainly composed of inclined and horizontal fissures. Based on this study, the mechanism of the two‐zone failure mode of overburden strata development was analysed according to the mining height and overburden strata key layer structure. This paper serves as a guide for safe and green mining on shallow buried thick seams.

As coal resources trapped under surface buildings in the Wangtaipu coal mine area impede the efficient mining of coal seams and constrain the sustainable development of coal mines, a super-high-water roadway backfill mining technique for preventing building damage was adopted. According to the control principle and theoretical calculations, an engineering design was established including the reasonable width of segment coal pillars in the working face and technical parameter design. The monitoring results after the implementation of the scheme showed that building deformation was controlled within grade I, protecting the surface buildings. A reasonable roadway design parameter was achieved, with a surface subsidence of 27 mm and horizontal deformation of 0.3 mm/m, indicating that it can ensure the safety of surface buildings from the State Bureau of Coal Industry. The practical trial can provide a reference for the extraction of coal resources under similar conditions and is vital for the sustainable development of the mining industry and economic growth.

Mining fracture is the key factor in realizing water-conservation mining, stability evaluation of coal mining subsidence areas, and accurate restoration of the surface eco-environment. To clarify, the evolution and distribution of mining fractures, based on the key strata theory and the mining degree of overburden failure, the contact state of rock stratum after overburden critical failure was analyzed, the formation mechanism of “saddle shaped” water conducting fracture zone was revealed, and the permanent mining fractures were determined to be primarily concentrated in the overburden structure at the boundary of the working face. According to the shear test of sandstone in the fracture zone, the damage degree of the rock sample was positively correlated with shear stress, and the overburden structure exhibited no instability. Based on the distribution of mining fractures, the fracture zone was divided into the original fracture, tensile fracture, structural void, and void compaction areas in the horizontal direction. The structural void area had the largest residual deformation in the goaf. A regional division method based on overburden critical failure was proposed and applied in engineering by using surface movement monitoring. The results showed that the surface subsidence near the boundary of working face was greater than that in the middle, and the residual surface deformation in the goaf was closely related to the mining time, which has long-term characteristics. The rationality of the regional division method of mining fractures was also verified.

During diagenesis, the transformation of unconsolidated sediments into a sandstone is usually accompanied by compaction, water expulsion, cementation and dissolution, which fundamentally control the extent, connectivity and complexity of the pore structure in sandstone. As the pore structure is intimately related to fluid flow in porous media, it is of great importance to characterize the pore structure of a hydrocarbon-bearing sandstone in a comprehensive way. Although conventional petrophysical methods such as mercury injection porosimetry, low-pressure nitrogen or carbon dioxide adsorption are widely used to characterize the pore structure of rocks, these evaluations are based on idealized pore geometry assumptions, and the results lack direct information on the pore geometry, connectivity and tortuosity of pore channels. In view of the problems, X-ray micro-CT was combined with ImageJ software (version 1.8.0) to quantitatively characterize the pore structure of Berea Sandstone. Based on its powerful image processing function, a series of treatments such as contrast enhancement, noise reduction and threshold segmentation, were first carried out on the micro-CT images of the sandstone via ImageJ. Pores with sizes down to 2.25 μm were accurately identified. Geometric parameters such as pore area, perimeter and circularity could thus be extracted from the segmented pores. According to our evaluations, pores identified in this study are mostly in the range of 30–180 μm and can be classified into irregular, high-circularity and slit-shaped pores. An irregular pore is the most abundant type, with an area fraction of 72.74%. The average porosity obtained in the image analysis was 19.10%, which is fairly close to the experimental result determined by a helium pycnometer on the same sample. According to the functional relationship between tortuosity and permeability, the tortuosity values of the pore network were estimated to be in the range of 4–6 to match the laboratory permeability data.

Most hilly areas are dotted with gullies, some of which contain plenty of water, especially in rainy seasons. Once surface water penetrates the underground working face, it will lead to an increased water inflow of the working face. Even worse, it may induce water and sand burst accidents. To prevent geological disasters such as water and sand burst and ensure the safe production in coal mines, it is necessary to reveal the development law of “two zones” in the overburden caused by shallow-seam fully mechanized top coal caving high-intensity mining in hilly areas with exposed bedrock and timely grasp the communication between the water-flowing fractured zone (WFFZ) and the water in surface gullies. In this study, the working face P2 of the exposed bedrock surface in the Coal Mine DN is taken as the research object. First, the characteristics of overburden movement and the law of exposed bedrock surface movement in areas with exposed bedrock were investigated through similar simulation. Meanwhile, the temporal–spatial evolution of overburden movement caused by shallow-seam fully mechanized top coal caving high-intensity mining was clarified, and the mode of overburden movement was revealed. Moreover, the reason why the water inflow of the underground working face increases suddenly was theoretically explained. The following conclusions were drawn: Under shallow-seam fully mechanized top coal caving high-intensity mining, the WFFZ of the working face P2 is directly connected to the exposed bedrock surface, and the movement of the overburden is subject to the typical “two-zone” mode. The development height of the WFFZ is greater than the value in the traditional “three-zone” mode calculated according to the empirical formulas. The ratio of the WFFZ height to the mining thickness is 43.75. Under the “two-zone” mode, a water-flowing channel exists in the overburden near the open-off cut and the stopping line. When the surface water source is in the right position, the water inflow of the underground working face will increase suddenly.