Loess landslides induced by the freeze–thaw effect frequently occur in Yili, China. Freeze–thaw cycles cause indelible changes in the soil microstructure, affecting its permeability. This study investigated the impacts of freeze–thaw cycles on the permeability of Yili loess using permeability tests on undisturbed (virgin, in situ) and remolded loess samples taken before and after freeze–thaw cycles. Scanning electron microscopy and nuclear magnetic resonance techniques were utilized to investigate the microscopic mechanism of the freeze–thaw process on the loess. Grey relation analysis (GRA) was employed to analyze the correlation between macroscopic permeability and microscopic parameters (maxi. radius, eccentricity, fractal dimension, directional probability entropy, and porosity). The results revealed that the permeability and all the microstructure parameters have roughly shown the same trend: “fluctuation–towards equilibrium–stability”. Firstly, the permeability coefficients of original and remolded loess experienced three and two peaked–trends, respectively, before 30 freeze–thaw cycles. The trends eventually stabilized within 30–60 freeze–thaw cycles. Increased number of freeze–thaw cycles disintegrated large particles in undisturbed loess into medium–sized particles, and particle shapes became more uncomplicated. Medium–sized particles in the remolded loess agglomerated to larger particles with more complex shapes. Furthermore, the overall porosity of the originally undisturbed loess decreased, and large and medium–sized pores transformed into small pores and micropores. In contrast, the overall porosity of remolded loess increased. Finally, the results revealed that permeability coefficients of the undisturbed and remolded loess became closely related with eccentricity and porosity, respectively. This study provides a reference for preventing and governing the loess landslides induced by the freeze–thaw cycles and permeability reduction in construction on loess in seasonally frozen areas in Yili.

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 destabilization mechanism of rainfall-induced loess landslides generally occurring in the Ili River Valley of China remains inadequately understood. This research investigates the variations accounting for the pore water pressure and vertical stresses in the landslide body during rainfall infiltration in Karahaisu landslide, Xinyuan County, Ili River Valley, China, through physical modeling tests together with the scanning electron microscope tests. The findings indicate that rainfall significantly increases the degree of water saturation within the slope, pore water pressure and vertical stresses. This increase is more pronounced in the later stages of rainfall, followed by a sharp decrease in both pore water pressure and vertical stresses post-landslide occurrence. The results also show the dynamic fluctuations in the size and structural complexity of soil particles and pores during the rainfall infiltration. Furthermore, the soil particles undergo fragmentation as a consequence of water infiltration, leading to soil body subsidence. This tensile fracturing, attributed to differential subsidence of the slope body, constitutes the fundamental cause of accelerated deformation and damage to the slopes. The evolution of continuous rainfall-induced landslides can be categorized into three stages: crack formation caused by compression and subsidence, uniform deformation by localized slip, and eventual damage by accelerated deformation.