The change of physical and mechanical properties of slope rock mass in open-pit mines in seasonally frozen area under the action of freeze–thaw cycles is one of the main reasons for slope instability. In this paper, taking the mechanical parameters of coal seam and sandstone layer in the Beitashan Pasture Open-Pit Mine in Xinjiang as the research object, considering the combined effect of the frost-heave tensile stress in the crack perpendicular to the crack surface and the three-dimensional confining pressure in the crack, the criterion for cracking of fractured rock mass under freeze-thaw condition is determined by applying the principle of stress superposition and the theory of strain energy density factor, and the theoretical frost-heave stress required for cracking is deduced. On this basis, the sensitivity analysis of the fixed factors and variable factors to the theoretical frost-heave stress was performed, respectively. Finite element analysis was utilized to analyze the slope stability under the attenuation of five groups of different rock mass mechanical properties and to determine the slope angle required for the slope stability. Seven different slope angles of sidewall mining ranging from 36° to 51° are analyzed. The results of finite element analysis show that considering the timeliness difference of rock mass parameters with time, the safety factor of slope is reduced from the original 1.70 to 1.18, and 91,500 tons of coal resources can be recovered every year, with remarkable economic benefits.

To address the challenge of simulating shear failure in anchor bolts within FLAC3D, a shear failure criterion, F_s(i) ≥ F_smax(i), is proposed based on the PILE structural element. Through secondary development using the FISH programming language, a modified mechanical model of the PILE element is established and integrated into the FLAC3D-FISH framework. Comparative analyses are conducted on shear tests of bolt shafts and on anchor bolt support performance under coal–rock interface slip conditions, using both the original PILE model and the modified mechanical model. The results demonstrate that the shear load–displacement curve of the modified PILE model clearly reflects shear failure characteristics, satisfying a quantitative shear failure criterion. Upon failure, both the shear force and axial force of the structural element at the failure point drop abruptly to zero, enabling effective simulation of shear failure in anchor bolts within the FLAC3D environment. Using the modified model, the distribution of principal stress differences in the surrounding rock after roadway excavation is analyzed. Based on this, the concept of a stress-bearing ring in the surrounding rock is introduced. The reinforcing effects of bolt length, spacing, and ultimate load capacity on the stress-bearing ring in weak and fractured surrounding rock are investigated. The findings reveal that: (1) shear failure initiates in bolt shafts near the coal–rock interfaces, occurring earlier near the coal–floor interface than near the coal–roof interface; (2) the stress-bearing ring in weak and fractured surrounding rock shows a discontinuous and uneven distribution. However, with support improvements—such as increasing bolt length, reducing spacing, and enhancing failure load—the surrounding rock gradually forms a continuous stress-bearing ring with more uniform thickness and stress distribution, migrating inward toward the roadway surface.

The weakly cemented argillaceous surrounding rock (WSR) presents significant challenges in underground roadways in Western China, characterized by water-induced softening, large deformations, and difficult stability control. This study systematically investigates the mechanism of water-induced deterioration and the corresponding control technology for roadways with WSR through laboratory experiments, numerical simulations, and field monitoring. Experimental results highlight the critical role of moisture content and confining pressure in dictating the strength and deformation response of WSR. UDEC Trigon simulations elucidate the evolution of fracture propagation and plastic zones under hydro-mechanical coupling, showing that the total damage degree in the roof increases dramatically from 48% to 97% as the water content rises from 2% to 12%, with a transition from a symmetrical to an asymmetrical failure pattern. To address this, a control technology using combined deep and shallow grouting reinforcement is proposed. COMSOL-based simulations optimize the grouting parameters, determining that the optimal grouting pressure is 1–2 MPa for shallow holes and 3–4 MPa for deep holes, with injection times of 6–8 min yielding diffusion radii of 1.5–2.0 m and 2.5–3.0 m, respectively. Field applications at the tailgate of panel 1801 in Dananhu No. 5 Mine confirm that this method successfully mitigates roadway deformation and secures prolonged stability. The findings provide both theoretical insights and a practical methodology for supporting roadways with WSR under challenging hydrogeological conditions.

There are a large number of argillaceous weakly cemented strata distributed in western China, and their significant hydraulic characteristics seriously restrict the safe and efficient exploitation of coal resources. In order to solve the problem of deformation and failure of the surrounding rock roadway in this type of strata, this study systematically studied the hydraulic disintegration behavior of argillaceous weakly cemented rocks by comprehensively using laboratory tests, theoretical analysis, numerical simulation and field experiments, established a constitutive model of argillaceous weakly cemented rocks considering hydraulic effects, revealed the deformation and failure mechanism of this type of surrounding rock roadway, and developed the combined support technology of high-strength anchor rod-anchor cable. The technology was applied and verified in the No. 5 mine of Dananhu Lake. The results are as follows: (1) The dried argillaceous weakly cemented rock specimens are more prone to disintegration than those without drying treatment; (2) A mathematical model that can describe the mechanical behavior of argillaceous weakly cemented rocks under hydraulic action is constructed, and the effectiveness of the theoretical model is verified by triaxial compression test. (3) The stress distribution and deformation law of the surrounding rock of the roadway under different moisture content conditions were analyzed: with the increase of moisture content, the stress concentration area of the surrounding rock gradually shifted to the depth, and the extreme value of the principal stress difference increased significantly, resulting in the risk of deformation and instability of the roadway intensified, and the proximity of the top and bottom plate in the middle of the roadway also continued to increase. (4) The joint support parameters are determined by numerical simulation optimization: the diameter of the roof plate and the two anchors is 2400 mm, the length is 2400 mm, and the spacing is 800 × 800 mm; The anchor cable has a diameter of 18.9 mm, a length of 6300 mm, and a spacing of 2400 × 2400 mm. (5) The field test shows that the subsidence of the roadway roof, the amount of two gangs moving closer, the amount of bottom drum and the degree of roof damage are reduced by 35%, 26.1%, 50% and 35.7%, respectively. This study provides a theoretical basis and technical support for the stability control of argillaceous weakly cemented rock roadway.

Disaster prevention and control of thick and hard roof breakage in longwall mining is a major technical problem faced by coal production enterprises. Taking 15311-south workings face of a mine as the engineering background, a mechanical model of thick and hard roof breakage in longwall workings was established to analyze the main influencing factors of the energy released by the initial and cyclical breakage of thick and hard roofs and the disaster-causing mechanism. The results show that the total energy released from hard roof breakage is positively correlated with the mining thickness, hard roof thickness, hard roof tensile strength and negatively correlated with the direct roof thickness, and the total energy released from the initial breakage of the main roof, is more than twice as much as that released from the cyclic breakage. Based on the production geological conditions, the parameters of directional long-drilling fracturing of thick-hard roof (fine sandstone) in 15311-south working face were determined as follows: single-point water injection volume of 20m3, spacing of fracturing points of 15m. Based on the control idea of “energy mitigation - structural weakening - stress regulation”, the “fixed-length drilling - hydraulic fracturing of thick-hard roof” was proposed. Based on the idea of “energy mitigation, structural weakening and stress control”, the three-dimensional fracturing technology of “fixed-length drilling, segmental fracturing and layered control” was applied in the field practice. On-site monitoring shows that: the maximum amount of coal pillar gangs moving in 15311-south tailgate is 236mm, the maximum amount of solid coal moving is 135mm, and the maximum value of roof and floor convergence is 287mm; the initial pressure step of the working face is reduced from 45m to 18m; compared with the non-fractured working face, the average reduction of the cycle pressure step of the quarry is 35%, and the scheme effectively ensures the safe and efficient mining of the comprehensive workface under the thick-hard roof.