For the shaft wall-tank structure in mining areas under thermal-fluid-solid three-phase coupling action, a combined method of numerical simulation and field monitoring was adopted. The “node displacement difference” of the beam-rod system structure was innovatively proposed to characterize the displacement of tank seams, and the influence of temperature and water head variations on the synergistic deformation of the structure were systematically analyzed. The results show that the increase in temperature causes the maximum vertical compressive stress of the shaft wall to increase by 24.35％, and the axial compressive stress of the tank beam to decrease by 25.63％, leading to the tank beam bending upward instead of downward. The overall structure shows a trend of thermal expansion. The reduction of water head increases the maximum vertical stress of the shaft wall by about 5 times, and increases the axial compressive stress of the tank beam by 24.45％. The extrusion deformation of the shaft wall triggers the delamination bending of the tank beam. In six working conditions, the increase in temperature and the reduction of water head lead to an increase of the vertical stress of the shaft wall by 21.1％, 20.9％, 19.6％ and 16.4％, 14.2％. The axial compressive stress of the tank beam increases as the water head decreases. The increase in temperature slightly weakens the growth amplitude of the shaft wall shear strain. The vertical displacement of the tank seam at the measuring point 3AA45 near the shaft wall is most affected by the three-phase coupling. The mathematical model shows that the influence of hydrophobic action on the vertical displacement of tank seams is 3.63 times that of temperature action. The research results can provide important references for the safety of the shaft wall-tank structure.

The stability maintenance of roadways with soft and broken surrounding rocks under complex conditions has always been a key technical challenge in the mining industry. To solve the problem of large deformation and damage in the short term after excavation and support in Longshou Mine of Jinchuan, research on secondary support of roadway with soft and broken rocks was carried out. The on-site investigation and analysis of the failure mechanism indicate that the main reasons for the instability of the roadway are the soft and fracture of the surrounding rocks and the failure of the floor filling to connect with the roof cavity. On this basis, a secondary support scheme of “grouting+anchoring net” was proposed, with 5 grouting holes evenly arranged on each grouting section, with a grouting hole depth of 2.2 m and a grouting spacing of 2 m. The parameters of the secondary anchoring net were the same as those of the initial support. The on-site application results show that the secondary support scheme significantly suppresses the deformation and damage of the roadway, reduces the deformation of the drift by more than 80%, and reduces the failure rate of the eyebrow line by 50%. There are no large-scale repairs during the entire production cycle, and the support effect is long-lasting and stable. The research results can provide reliable technical reference and practical basis for the support design of roadway with soft and broken rocks in similar mines.

Adding plastic expansion agent is an effective measure to improve the volume stability of mine grouting materials. By preparing mine grouting materials with plastic expansion agent, the influence of plastic expansion agent on its working performance, rheological properties, mechanical properties and volume stability was investigated. Then, the mechanism was elucidated through the analysis of pore structure and microscopic morphology. The results show that with the increase of plastic expansion agent content, the working performance and rheological property of the grouting materials are improved, the compressive strength and flexural strength decrease, the plastic expansion rate increases gradually at 3 h, but the influence on volume deformation is small in the middle and late stages. The total porosity and average pore size of the hardened slurry are increased significantly after the addition of plastic expansion agent. When the addition rate is higher than 0.12％, the proportion of capillary pores and large pores are increased more. Considering the performance parameter requirements of grouting materials, it is more suitable when the plastic expansion rate is in the range of 0.04％－0.08％.

A method based on graph neural network (GNN) clustering was proposed for the regional classification of mountain flood risk in open-pit mining areas, so as to address the issue of spatial relationships neglected in existing classification methods. The research area selects the Baiyunebo mining area, and the classification method of mountain flood risk in mining area mainly consists of three steps. Firstly, the remote sensing images of the mining area were selected to divide into grid units and each grid was used as a node of the map. The node features mainly included elevation, slope, aspect, rainfall and precipitation. Secondly, the cosine similarity method was used to calculate the similarity of environmental features and represent the spatial relationship of similar nodes as edges, constructing an adjacency matrix. Thirdly, the constructed graph and corresponding adjacency matrix were input into the network model, which adopted an encoder architecture consisting of graph sample and aggregate (GraphSAGE) and graph attention network (GAT). The KL divergence loss function was used to optimize the model, ultimately achieving clustering prediction of the classification of mountain flood risk in the Bayyunebo mining area. The experimental results show that the clustering accuracy of the model reaches 87.5%, which is 11.2, 9.4 and 5.3 percentage points higher than traditional clustering algorithms k-means, hierarchical clustering, and random forest, respectively. The research result can verify the ability of this method to classify mountain flood risk in open-pit mining areas and can provide a reference for the prevention of mountain flood in open-pit mining areas.

In order to comprehensively evaluate the impact of mine geological hazard on the ecosystem, the mining disturbance index was constructed and incorporated into the risk assessment system of geological hazard. At the same time, the impact of mine geological hazard on the regional ecological security pattern was incorporated into the vulnerability assessment system to characterize the particularity of geological hazard inducing factors in mining cities and enrich the connotation of geological hazard vulnerability in mining cities. The results of risk assessment of geological hazard in Daye City show that the areas of extremely high, high, medium and low risk areas are 95.67 km², 230.57 km², 349.64 km² and 890.41 km², accounting for 6.11％, 14.72％, 22.32％ and 56.85％, respectively. The extremely high and high risk areas are mainly distributed in the areas with frequent mining engineering activities such as Jinhu, Dajipu, Jinshandian, Huandiqiao, Luoqiao, Lingxiang, Chengui and Liurenba. Mine wasteland and mining disturbance are the main causes of geological hazard. It is necessary to strengthen the restoration and treatment of mine wasteland and adopt green mining methods.

Based on the experiential knowledge of mine safety experts, a multi-level safety comprehensive evaluation index system and evaluation model for underground mines were established from 8 aspects, including the “three synchronizations” procedure for safety facilities, safety production organization guarantee, safety education and training, dual prevention mechanism, production system safety guarantee, hazardous materials and hazardous operation management, emergency management, and outsourced project management. The analytic hierarchy process (AHP) was adopted to calculate the weight of each index, and a safety comprehensive evaluation set was established to determine the comprehensive safety evaluation results of metal and non-metal mines. Practical application demonstrates that a certain underground metal mine in Hengyang has achieved a comprehensive safety evaluation score of 73.1, which is classified as “Medium”. Among the evaluation aspects, the mine has obtained relatively low scoring rates in hazardous materials and hazardous operation management, production system safety guarantee, as well as emergency management and outsourced project management. The established comprehensive safety evaluation results are basically consistent with the actual situation of the mine, and can effectively improve the scientificity and practicality of the safety comprehensive evaluation for underground metal and non-metal mines. The evaluation process not only helps enterprises identify weak links in safety production, but also provides a theoretical basis for further consolidating the safety foundation, strengthening safety management, and enhancing the safety level.

In-situ stress measurement is one of the indispensable basic work in deep resource mining engineering. Diametrical core deformation analysis (DCDA) method, which measures the diametrical deformation of the core samples, is not limited by the borehole depth. It offers advantages of convenient operation and reusability for obtaining in-situ stress information from deep boreholes. Based on the principle of DCDA method and high-precision laser ranging technology, a core orientation method using borehole images and core surface scanning was proposed, which realized the determination of the geographical orientation of the core samples, and determined the direction of the horizontal principal stress by the radial ellipse shape of the oriented core. This method was applied to the deep hole in-situ stress measurement of a phosphate mine in Guizhou, and verified by hydraulic fracturing method. The results show that the maximum horizontal principal stress direction determined by DCDA method is NE66° to NE81°, and the maximum horizontal principal stress direction determined by hydraulic fracturing method is NE64° to NE80°. The minimum deviation value determined by the two methods is 3°, and the maximum deviation value is 17°. At the same depth, the deviation of the maximum horizontal principal stress value determined by the DCDA method and the hydraulic fracturing method is within 5.0％, and the results measured by the two methods are basically the same. A new idea of in-situ stress measurement combining diametrical core deformation analysis method and differential strain curve analysis method (DSCA method) was proposed. The two methods complement each other in data utilization and can calculate the three-dimensional stress value of underground rock mass.

Borehole pressure relief is a widely adopted prevention and control measure to mitigate the risks of high-stress dynamic loads on roadways. An appropriate pressure relief hole diameter is of great significance for the protection of roadways against rock bursts. To investigate the influence of pressure relief hole diameter on the dynamic response characteristics of surrounding rock under dynamic loads, a split Hopkinson pressure bar (SHPB) test system was used to conduct dynamic impact tests on prefabricated borehole specimens containing different hole diameters. The effects of pressure relief hole diameter on the dynamic mechanical properties, failure characteristics, and energy dissipation of the specimens were analyzed. The test results reveal that an increase in hole diameter leads to a reduction in peak stress and peak strain. Specifically, the reduction amplitude of peak stress gradually decreases as the hole diameter increases, while the reduction amplitude of peak strain gradually increases. Under dynamic load, the final failure mode of all specimens containing holes is dominated by X-shaped tensile-shear composite failure. However, the angle between the tensile-shear composite cracks and the loading direction, the development and expansion degree of initial tensile cracks before closure, and the development degree of far-field cracks are affected by the hole diameter. The presence of holes indirectly provides stress conditions for the development of fractures in the specimens. Therefore, the fractal dimension increases with the increase of hole diameter. However, when the hole diameter exceeds a certain threshold value, the specimens have been destroyed before the development of fractures, leading to a decrease in the fractal dimension. The energy dissipation ratio of the specimens is similar to their fragmentation characteristics, showing a trend of first increasing and then decreasing with the increase of hole diameter. This phenomenon is mainly related to the delay effect caused by different hole diameters. The research results provide a certain guiding significance for the optimization of pressure relief hole diameter in deep roadways threatened by dynamic loads.

To investigate the effects of hydrochemical and freeze-thaw (HFT) on the physical properties and shear mechanical characteristics of andesite, freeze-thaw tests were conducted for 45 cycles under three different hydrochemical environments. The andesite samples from the Duolong mining area in Tibet was selected as the research object. The changes in shear mechanical parameters and physical properties, as well as the damage mechanisms, were analyzed from both macroscopic and microscopic perspectives. The results show that, as the number of freeze-thaw cycles increases, both the physical properties and shear mechanical parameters of andesite in all three hydrochemical environments exhibit a deterioration trend, with the most significant damage observed in the acidic environment. The decrease in cohesion is more pronounced than that in the internal friction angle, and the failure modes differ among environments: shear failure in acidic environments, shear fracture failure in neutral environments, and tensile shear failure in alkaline environments. A shear mechanical prediction model based on shear test data was established, with an error of less than 10%, which can effectively predict the cohesion and internal friction angle values of the rock after long-term freeze-thaw cycles in different chemical environments. Quantitative analysis of damage caused by hydrochemical and freeze-thaw effects based on shear test parameters shows that freeze-thaw cycles cause more damage to andesite than hydrochemical effects.

In order to explore the effect of shear slip on the communication and connection of multiple tensile cracks in shale, based on the indoor compression-shear test, the fracture process of shale with different bedding angles was studied by PFC2D from the microscopic point of view. The characteristics of initiation, propagation, communication and connection of en-echelon fracture, as well as the effect of bedding direction, were analyzed, and the influence of each main control factor on en-echelon fracture was discussed. The results show that in the compression-shear fracture process of shale, the en-echelon tensile fracture of the oblique shear plane first initiate near the shear plane. When the expansion of the en-echelon fracture gradually slows down or even is blocked, the shear cracks initiated from both ends of the shear plane rapidly expand and penetrate the en-echelon fracture, forming a macroscopic shear fracture zone. The morphology of en-echelon fracture formed in the process of compression-shear shows obvious bedding direction effect. The shale with bedding angle of 0° is sheared along the bedding, and no en-echelon fracture are formed. The shale with bedding angle of 30°, 45°, 60° and 90° forms en-echelon fracture with uniform oblique bedding, while the shale with bedding angle of 120°, 135° and 150° forms en-echelon fracture along bedding or oblique bedding, and the scale of en-echelon fracture shows anisotropic characteristics. The en-echelon fracture formed in the process of compression-shear fracture are mainly tensile cracks, and the en-echelon fracture are mainly connected by shear cracks to form shear fracture zones. The number of bedding has no obvious effect on the shape and scale of en-echelon fracture propagation. With the increase of bedding cementation strength, the scale of en-echelon fracture shows a certain weakening trend, and the width and size of shear fracture zone are obviously reduced.