To clarify the development and height of the fractured water-conducting zone of underground mines with weakly cemented overburden, the W8203 working face of the Tashidian Erjingtian Mine in Xinjiang, China, was selected to carry out a case study. Firstly, a physical analog model test was conducted to investigate the development law of the water-conducting fracture zone, followed by a numerical simulation via the PFC2D program. Afterward, a theoretical analysis based on the key stratum theory was carried out. The results demonstrated that there were one primary key stratum and three sub-key strata upon the W8203 working face. As verified by the physical analog tests, the water-conducting fracture developed to the bottom of the primary key stratum, and the height of the fractured water-conducting zone was 246.38 m. The numerical analysis suggests that the primary key stratum did not completely break and the fracture did not penetrate the stratum. Theoretical calculation indicated that the primary key stratum maintained stability in the structure without any breakage. The height of the fractured water-conducting zone is comprehensively determined to be 246.38 m, which is relatively close to the measured value (229.32 m). Based on the prediction method of key stratum position combined with the characteristics of weak cemented overburden, a method to predict the height of a water-conducting fracture zone suitable for weak cemented overburden was developed. The accuracy of this method was also verified through an in-depth comparison with field test results. Under the background of the “strategic westward shift” of coal resource exploration and development in China, the research results can provide theoretical and technical support for safe production in the Tashidian Mining Area and references for green and safe production in weakly cemented overburden mining areas in western China.

The overlying weakly cemented, and poorly performing strata in Jurassic mines of western China have mechanical properties that are generally lower than those in the Carboniferous-Permian coal mines of central and east China. During coal mining, the overlying strata easily deform and fracture. These then formed water-conducting channels, triggering a series of eco-environmental issues, including ground fracturing, collapsed surfaces, declined underground water levels, deserted lands, and even severe water/sand burst accidents. To study the fracture characteristics of weakly cemented overlying strata and the evolution law of water-conducting fractures in Jurassic coal mines in western China, this study selected Tashidian Erjingtian Mine in Korla, Xinjiang, as the research object. Based on the simulation data obtained with physical analog model testing and field monitoring results, the authors investigated the development of water-conducting fractures in the weakly cemented overlying strata during the coal seam mining process. We simultaneously determined the location of key strata in the working face based on key stratum theory. According to the present research results, key strata controlled the development height of water-conducting fractures. When the primary key stratum or sub-key stratum was not fractured, the development of water-conducting fractures was stagnant; water-conducting fractures developed abruptly when the primary key stratum or sub-key stratum was cracked. The heights of water-conducting fractures in the weakly cemented overlying strata of western China exceeded that of similar stopes of central and east China. These research results provided theoretical and technical support for safety in production at Tashidian Coal Mine. In addition, they offered a reference for green and safe production in Jurassic coal mines of western China.

The distribution of reclaimed soil particle size under seepage conditions after the management period will directly determine the success or failure of reclamation work. The geotechnical experimental method was used in this paper to study the changes in the granulometric composition of soil. The results show that the granulometric composition of the reclaimed soil varied obviously at different depths. The granulometric composition of the soil at a depth of 10 cm was not much different from undisturbed reclaimed soil (URS). At a depth of 30 cm, as the sharp decrease of the content of fine particles resulted in coarser reclaimed soil, the soil became more uniform, with an increase in porosity and water content. At a depth of 50 cm, the fine particle content was generally slightly lower than that of URS. At a depth of 70 cm, the fine particle content of the soil greatly exceeded that of the URS, with the finest soil particles and lowest porosity. The main reason for the above-mentioned changes of granulometric composition in the reclaimed soil was the seepage in soil caused by irrigation during the management period. The research results can provide a reference for management after land reclamation at non-metallic mines in Xinjiang, China.