The shotcrete lining in the underground water sumps of the Shen Dong coal mine in western China has been subjected to long-term exposure to harsh environmental conditions, including repeated dry-wet cycles and high salinity. The elevated chloride ion concentration in the mine water exerts a pronounced corrosive effect on the shotcrete. The performance degradation of shotcrete in highly erosive environments has become a technical bottleneck restricting the long-term safety and reliability of shaft and tunnel engineering. This paper takes the shotcrete in the underground water sump of Shigetai Coal Mine in Shendong Mining Area as the research object. Combined with the surrounding environmental conditions, theoretical analysis is carried out, and a diffusion model of moisture and chloride ions is established. The erosion rate of chloride ions is regarded as the evaluation index in coal gangue shotcrete and ordinary shotcrete. Firstly, the COMSOL simulation software is employed to simulate the erosion rate of 40% coal gangue shotcrete under various water–cement ratios. It is concluded that the coal gangue shotcrete has the strongest resistance to chloride ion erosion when the water–cement ratio is 0.4. Secondly, the erosion rates of chloride ions in coal gangue shotcrete and ordinary shotcrete are, respectively, compared under the optimal water–cement ratio. It is ascertained that coal gangue shotcrete has a stronger ability to resist chloride ion erosion under the same water–cement ratio. Finally, the erosion depth of chloride ions in coal gangue shotcrete and ordinary shotcrete is studied through experiments, and the chloride ion concentration on the surface of specimens at different erosion ages. The research finds that the experimental results are basically consistent with the numerical simulation results. The results indicate that coal gangue shotcrete with a 40% replacement rate of coal gangue and a water–cement ratio of 0.4 exhibits the highest resistance to chloride ion penetration. Furthermore, a novel approach is proposed for investigating chloride ion erosion in concrete, which involves establishing a moisture-chloride ion diffusion model and performing numerical simulations. The approach aims to reduce the loss caused by multiple experiments, save experimental costs, and time. It is also proposed to prepare shotcrete with coal gangue to consume a large amount of coal gangue and reduce the discharge of coal gangue, and a new method is provided for the comprehensive utilization of coal-based solid waste.

Coal gangue concrete in high, cold mines in western China is subject to freeze–thaw damage due to prolonged low temperatures and large temperature variations, leading to surface spalling, cracking, and degradation of mechanical performance. In this study, four coal gangue concrete mixtures with replacement ratios of 0%, 20%, 40%, and 60% were prepared using gangue from the Halagou Mine in the Shendong area. Freeze–thaw cycle tests were conducted to analyze the effects of the replacement rate and number of cycles on compressive strength, elastic modulus, and peak strain. The results show that both compressive strength and elastic modulus decrease with increasing freeze–thaw cycles, while the peak strain increases. After 80 cycles, the compressive strength of the M0, M20, and M40 groups decreased by 35.0%, 41.8%, and 51.1%, respectively, and their elastic modulus dropped by 49.2%, 86.2%, and 92.0%. The M60 group was too severely damaged to be tested. Based on the experimental data, a constitutive model for coal gangue concrete under freeze–thaw conditions was developed and validated using Abaqus finite element analysis, with simulation errors below 10%. Considering both mechanical performance and resource utilization, the optimal coal gangue replacement rate is determined to be 20%.

The performance degradation of concrete structures in underground water sumps within the Ordos mining area has become increasingly prominent due to environmental factors, particularly the sulfate-induced dry–wet cycles. These conditions lead to the development of cracks, spalling, and structural instability, which poses significant safety risks. This issue must be addressed with consideration of the regional hydrogeological characteristics and the current requirements for safe, sustainable, and environmentally responsible coal mining practices. The study investigates the concrete employed in the underground central water reservoir of Bulianta Coal Mine in the Ordos mining area. A novel approach is proposed for developing sulfate-resistant concrete capable of withstanding dry–wet cyclic conditions in underground environments through the utilization of coal gangue sourced from the same mining operation. Considering concrete performance, cost-effectiveness, and coal gangue utilization, a laboratory mix optimization study was conducted and the optimal mixture proportion was determined to be a 60% gangue content, a 30% fly ash content, a water–binder ratio of 0.38, which produced concrete with a compressive strength of 31 MPa. Sulfate resistance tests were conducted on the optimal mixture of dry–wet cycle-resistant concrete. The effect of different dry–wet cycle counts on the compressive strength of the coal gangue concrete was investigated, and the evolution patterns of the ascending segment shape coefficient a and descending segment shape coefficient b under sulfate-induced dry–wet cycling were analyzed. Combining the Guo Zhenhai concrete constitutive model, a concrete constitutive model suitable for the dry–wet cycle conditions of sulfate was established. Based on the proposed constitutive model, the uniaxial compressive mechanical behavior of coal gangue concrete subjected to sulfate attack was investigated through numerical simulations using the Abaqus (2020) software. The simulation results are basically consistent with the laboratory results, which proves the applicability of the constitutive model and confirms the performance of the optimal proportioning scheme for preparing sulfate-resistant dry–wet cycle concrete using coal gangue from underground mines. This study provides a new type of concrete for similar underground conditions in this mining area and offers a new approach for the comprehensive utilization of coal gangue.

This study investigates the asymmetric evolution of overburden deformation and fracture during unilateral roof cutting in a deep pillarless longwall panel. The No. 31120 working face at Suncun Coal Mine was used as the prototype for a 1:40 physical similarity model. Fracture observations, digital image correlation fields, subsidence profiles, and paired vertical-stress histories were analyzed throughout support advancement, sustained support, and support withdrawal. The maximum-subsidence region and dominant fracture boundary shifted toward the non-cutting side, whereas the cutting side developed smaller caved blocks and a shorter retained roof span. A longer cantilever-like roof segment formed on the non-cutting side and a shorter segment formed on the cutting side, accompanied by contrasting loading and unloading responses at corresponding roof levels. The combined observations show that unilateral roof cutting redirects roof fracturing and load transfer and provide an experimental basis for evaluating retained roof span, separation, and support demand near a gob-side roadway.