The height of the water‐conducting fractured zone (WCFZ) is a basic parameter related to water protection in coal mines and is also crucial for aquifer protection and mine safety. In order to accurately detect the height and shape and reveal the formation mechanism of the WCFZ, which is caused by middle‐deep coal seam mining in a sandy region, the 112201 coalface at the 1# coal mine of Xiaobaodang was taken as a case study. Filed measurements including fluid leakage, borehole TV, and similar simulation were adopted to analyze the regularity of the WCFZ in this area. The detection results of field measurements showed that the maximum height of the WCFZ was 177.07 m in a borehole near the open‐off cut, and the ratio of the height of the water‐conducting fractured zone divided by the mining thickness was 30.53. The WCFZ acquired an inward‐convergent saddle shape, which was inclined to the goaf. The saddle bridge was located at the boundary of the goaf, and the saddle ridge was located at the center of the goaf. Also, through analyzing the results of similar simulations, we found that, in the process of mining, separation cracks and the beam structure were the main forms of overburden disturbance transmitting upward and ahead of mining, respectively. The main cause of the increase in height of the WCFZ was the connection of the separation cracks and vertical cracks caused by fractures of beam structures. The development of the WCFZ was divided into five stages: incubation stage, development stage, rapidly increasing stage, slowly increasing stage, and stable stage. Moreover, the duration of each stage was related to the lithology and mining technology. This research can provide significant theoretical insights for the prediction of the WCFZ, enabling the prevention of water hazards on mine roofs and assisting with water resources protection.

Surface damage caused by coal mining is one of the problems perplexing ecological environment restorations in coal mining areas. Accurately evaluating and predicting the degree of surface damage induced by coal mining with reasonable and correct indexes are of great significance to the restoration and treatment of the ecological environment. In this paper, these methods including the unmanned aerial vehicle aerial photography and manual measurement were used to investigate the development characteristics of surface damage caused by 2^# coal seam mining in Yangchangwan Coal Mine. The results showed that with the change of mining conditions, the characteristics of surface cracks change obviously, which can be adopted to indicate the degree of surface damage. Thus, based on the results of the investigation, the classification standard of surface damage degree was established based on the evaluation indexes including density of crack, drop height of surface crack, crack width, maximum surface subsidence, and geological disaster caused by cracks and the damage characteristics of buildings. The evaluation method and process of surface damage degree also were given. Based on the ratio of the buried depth to the thickness of the coal seam (H/M), ratio of the thickness of overlying bedrock to the thickness of the coal seam, the thickness of loose layers (Ms), geomorphology, distance to faults, and distance to folds, the prediction model of surface damage degree was built on the GIS platform. The weight coefficient of each prediction index was obtained by the analytic hierarchy process (AHP) method. The surface damage degree map of 2^# coal seam in Yangchangwan Coal Mine was divided into four classes: very minor, minor, moderate, and serious, which provides a relatively applicable method for the prediction of surface damage degree in Yangchangwan Coal Mine and its adjacent mining areas.

Compared with single coal seam mining, the stratum damage induced by shallow multi-seam mining is more severe and poses a risk of mine disasters that threaten the safety of coal mine personnel. In order to reveal the characteristics and mechanism of strata damage, in this paper, field measurement, numerical simulation and mechanical analysis are used to study the development characteristics and dynamic evolution laws of overburden and explain the dynamic evolution mechanism of a water-conducting fracture zone (WCFZ) and surface cracks. The height of the WCFZ to the mining height exceeds 31.68, which is higher than the empirical value of the study area. There are self-healing and activation laws for overburden fissures in shallow multi-seam mining, which is related to the hinge rotation of overburden and the deflection of the inclined structure. However, the maximum subsidence coefficient and crack angle of the surface induced by shallow multi-seam mining does not alter, but the complexity of surface crack activity increases. The dynamic development law of WCFZ is closely related to the breaking of key strata, while the dynamic evolution of surface crack is controlled by the form of surface block fracture instability and topography. In addition, a shallow multi-seam horizontal staggered mining model that is conductive to reducing surface damage is constructed, and a method has been proposed to lessen the risk of landslides brought on by surface cracks.

The development height of the water-conducting fractured zone (H_WCFZ) serves as an important basis for the prevention of mine water disasters and assessment of water resource impacts. In recent years, with the increasing adoption of super-wide coal mining longwall panels with a width exceeding 300 m, studies on their H_WCFZ have been limited and relevant field measurement data remain sparse. This study aimed to determine the development H_WCFZ in super-wide longwall panels during the mining of medium-depth coal seams. The research area comprised the adjacent 01 and 02 fully mechanised longwall panels in Xiaobaodang No. 2 Coal Mine, China, with widths of 300 m and 450 m, respectively. The development H_WCFZ was determined via drilling exploration and numerical simulation. The results revealed that compared with the conventional longwall panel with a 300 m width, the H_WCFZ in the central area and near the boundary roadway area increased in the super-wide longwall panel with a 450 m width. The H_WCFZ increased by 6.4 m and 5.9 m, corresponding to growth rates of 11.3% and 8.4%, respectively. The H_WCFZ in the boundary areas of both longwall panels was greater than that in the central areas, exhibiting a saddle-shaped distribution characterised by lower values in the middle and higher values on both sides along the inclination direction. According to the numerical simulation results, the width of the coal mining face exhibited a nonlinear positive correlation with the maximum H_WCFZ. A width of 300 m represented the threshold at which the rate of increase of the H_WCFZ began to decline, whereas a width of ~450 m represented the critical threshold beyond which the H_WCFZ tended to stabilise. These findings offer valuable insights for the accurate prediction of the H_WCFZ in super-wide longwall panels, the prevention of mine water disasters and assessment of water resource impacts.