Based on the continuous mining project of the deep double middle sections in the second mining area of Jinchuan Nickel Mine, numerical analysis of ground pressure control in the panel of deep double middle sections was carried out. By comparing the distribution of maximum unbalanced force, stress, and displacement field in the lower panel under five different schemes of ground pressure control technology, it was found that Scheme Ⅴ (advanced unloading through the upper and lower panels and trapezoidal approach with two mining intervals) had the best ground pressure control effect, with the lowest extreme value of maximum unbalanced force (1.20×10⁸ N). The maximum principal stress of the backfill at the top of the panel was negative and no tensile stress was observed. Compared with Scheme I (advance unloading through the vein in panel and rectangular approach with one mining interval), Scheme V has an average minimum principal stress increase of 0.11％ and a maximum compressive stress increase of 1.56％. During the mining process, the tilting deformation of the backfill on the roof of the panel is minimized. The optimization of the ground pressure control technology scheme for the deep double middle sections shows that the “positive trapezium + concave” technology scheme has smaller stress fluctuations and displacement deformations, and the ground pressure control effect is better. The application and stability analysis results of deep mining engineering show that after adopting the optimized scheme of ground pressure control technology, the ore output of the mining area can meet the production capacity requirement of 4 million tons per year. The increase in frequency of microseismic events is relatively slow, and microseismic events occur uniformly without sudden clustering. The overall frequency coefficient of roadway damage in the 1 000 m middle section shows a decreasing trend year by year, which verifies the rationality of the ground pressure control technology scheme for the panel in deep double middle sections.

The Xitieshan lead-zinc mine has left a large amount of high-grade ore pillar resources after years of mining, and there is an urgent need to recover the top and bottom pillars in a safe and efficient manner. It is found that the strength of underground filling body can't meet the conditions for large-scale exposure in the bottom pillar mining area through on-site sampling and strength testing of the filling body above the bottom pillar, and it is necessary to leave roof protection pillars. Based on the test results, three technically feasible mining schemes were proposed, including the joint mining method of sublevel open stoping with subsequent filling and upward access empty field, mining method of false roof and segment subsequent filling, as well as mining method of pre-controlled roof and downward medium and deep hole segment subsequent filling. A comparative analysis was conducted on the advantages, disadvantages, and technical and economic indicators of the three mining methods. Finally, the the joint mining method of the segmented subsequent filling and upward access was selected. Numerical simulation was used to determine that the medium deep hole mining area adopts the mode of mining one with two intervals, and in a sequence from both sides to the middle, and a backward extraction method was used to extract partially pillars during the mining process of the access. The on-site application results show that this scheme has good safety and adaptability in the mining of top and bottom pillar resources, with a comprehensive recovery rate of 70％, achieving efficient recovery and utilization of top and bottom pillar resources.

The ore body above 180 m level in the west section of Dahongshan Copper Mine belongs to the gently inclined medium-thick ore body, which was originally mined by the point-column upward horizontal slicing-and-filling method. However, with the continuous expansion of the mining scope and level, the stress concentration around the mining zone became increasingly evident, the unmined areas and the stope were located within the stress concentration zone and the plastic zone, leading to a growing safety risk for the roof. According to the characteristics of ore body and the actual situation of the site, the optimization study of mining in transition area between two minging schemes was carried out. After optimization, the transition area was mined using the sublevel open stoping with subsequent filling method, and cemented backfilling was employed to construct cemented ore pillars in the transition area. Analysis and study on the layout of mining preparation projects in the transition area under two mining schemes were carried out. The results show that the transition area is mined by sublevel open stoping with subsequent filling method, and the cemented pillar formed by cemented filling has a good supporting effect. The maximum plastic zone height of stope roof is 7-8 meters, and the layout of the filled return airway is not affected. The application effect shows that the stope in the transition area remains stable overall, achieving safe and efficient resource recovery in the area.

To investigate the influences of endwall roughness and ore grading condition on the ore drawing effect of non-pillar sublevel caving method, based on a single segment and single access ore drawing model, the joint roughness coefficient (JRC) of rock structure surface was introduced to quantify the endwall roughness. Physical experiments were conducted under five types of endwall roughness and two types of ore grading conditions, and the changes in recovery rate, dilution rate, and release amount of ore, as well as the development characteristics of the release body morphology, were systematically analyzed. The results indicate that the endwall roughness and the ore grading conditions have a significant impact on the flowability of the ore, thereby determining the variation characteristics of the recovery rate and dilution rate. As the proportion of fine particles in the ore grading and the endwall roughness decrease, the ore recovery rate shows an upward trend. The dilution rate shows a trend of first increasing, then decreasing, and then increasing again as both factors increase. When the content of fine particles is low and the JRC value is 0, the ore flowability is the optimal, the recovery rate is the highest at 75.15％, and the dilution rate is the lowest at 32.09％. In addition, reducing the proportion of fine particles in the ore grading and decreasing the endwall roughness can promote the development of the transverse axis length and suppress its height development of the ore release body, thereby increasing the ore recovery rate and optimizing the overall ore drawing indicators.

Multi-outlet ore drawing method is commonly adopted in underground mine production, and there is often an obvious arching phenomenon during the ore drawing process. To investigate the influence of multi-outlet ore drawing on the arching of granular ores, based on the theory of lateral pressure of granular materials, a lateral pressure testing system for granular material flow was used to conduct physical similarity simulation experiments under single-outlet, double-outlet, and triple-outlet ore drawing conditions. The distribution laws of lateral pressure of granular ores under different ore drawing methods and filling heights were obtained, so as to further analyze the ore arching phenomenon. The research results show that when the filling height is 75 cm, the ore arching phenomenon under triple-outlet ore drawing is relatively obvious, and the arching strength is the highest. The location of arching is less affected by the ore drawing method, and obvious arching phenomena mostly occur at 55 cm above the ore outlet. Under the condition of triple-outlet ore drawing, the filling height further affects the formation of arching and the location of its occurrence. When the filling height is 85 cm, obvious arching phenomena occur at 55 cm and 75 cm above the ore outlet, and the ore in the lower area shows a tendency for arching. When the filling height increases to 95 cm, the area where obvious arching phenomena occur extends downward.

To further investigate the flow characteristics of the ore drawing process of ore-rock with different water contents in steeply inclined extremely thin veins, so as to optimize mining processes and improve resource recovery rates, a combined method of physical tests and numerical simulation was adopted, and a full-scale numerical model of ore drawing in confined space for steeply inclined extremely thin veins was established. Through repose angle calibration tests on ore-rock with different water contents, the discrete element simulation parameters were determined. Full-scale numerical simulations of ore drawing were carried out, and the ore drawing characteristics of ore-rock with different water contents under different ore drawing heights were analyzed. The results show that the water content of ore-rock particles has a significant impact on the flow characteristics of ore-rock. When the water content of ore-rock is 4％, the ore drawing fluidity is optimal with a large and stable flow rate, and it exhibits a “first-in first-out” flow regime. As the water content increases, the ore drawing fluidity distorts and gradually transitions to a “first-in last-out” flow regime, while the ore drawing flow rate decreases, failing to meet the requirements for simultaneous operation of multiple ore drawing outlets. In addition, when the water content of ore-rock is 4％, ore drawing heights have a relatively small impact on the fluidity of ore-rock particles. As the water content increases, the increase in ore drawing heights worsens the fluidity of particles at higher positions, and when the water content is 15％, the particle fluidity deteriorates severely.

The difficulty of controlling the blasting effect of fan-shaped blasting holes in the non-pillar sublevel caving method significantly affects the mining efficiency in the mining area. Research was conducted on the issues of high large block rate and poor ore recovery index as well as poor safety of mining operations in the 1 580 m sublevel caving stope under the condition of broken ore-body in the west No.2 mining area in Longshou Mine. The analysis shows that the main reason of the high block rate is that the side holes in upper sublevel edge are buried by the blasting pile and not fully blasted, and the serious blockage of the blasting row holes in this section results in insufficient charging. Analysis shows that a high block rate can have adverse effects on the mining indicators, operational safety, mining efficiency, and mining costs of the mining area. In order to reduce the large block rate in the mining area, a series of technical and management measures were proposed, including optimizing the form and size of the mining drift, improving the parameters of fan-shaped blast holes, introducing through hole equipment suitable for the working environment, testing pre-charge technology, and strengthening blasting quality management. The large block rate in the mining area has been successfully reduced from 16％ to 5％, the ore recovery index in the mining area has been increased from 68％ to 82％, and the safety of the mining area has been significantly improved.

Since the filling mining technology was adopted in Jinchuan Longshou Mine, the filling quality has not been systematically studied. Based on this, a follow-up survey of the filling quality of the downward layered cemented filling method in Jinchuan Longshou Mine was carried out for half a year, and the key factors affecting the filling quality were analyzed. Combined with the results of investigation and research, the filling quality control measures were put forward. The survey results show that the quality of mine filling materials is poor, the filling body is not completely connected to the roof, the strength of the filling body fluctuates greatly, and the number of abnormal parking times has a great impact on the filling quality. The field practice shows that the filling quality can be improved by ensuring the unit consumption of cementitious materials and the quality of filling materials, improving the roof-contacted filling rate, reducing the frequency of abnormal parking, improving the uniformity of slurry and ensuring reasonable mass concentration of slurry.

Aiming at the problems of short pumping distance and easy plugging of gravel filling slurry in Datun Tin Mine, it was proposed to add copper slag tailings fine material to the gravel to improve the aggregate gradation, and the gravel-copper slag tailings mixture ratio test was carried out. It was concluded that when the proportion of gravel mass reached 60％, the packing density of mixed aggregate reached the maximum value. Further, through the strength test of backfill, rheological test, high concentration and high flow state test, the mix ratio of gravel-copper slag tailings paste was determined, which meets the strength requirement of filling body, no segregation of paste and self-leveling. Based on the actual filling situation of 32^# stope in Datun Tin Mine, the numerical simulation method was used to analyze the change law of pipeline resistance of gravel-copper slag tailings paste. The results show that the optimal mix ratio of gravel-copper slag tailings paste is gravel∶ copper slag tailings ＝ 6∶4, and the cement dosage are 270 kg/m³ (mass concentration 82％－83％), 240 kg/m³ (mass concentration 83％－84％), 210 kg/m³ (mass concentration 83％－84％), 180 kg/m³ (mass concentration 83％－85％), respectively. The resistance loss of gravel-copper slag tailings paste along the horizontal pipeline is 6 105.76－6 525.11 Pa/m, and the limit pumping horizontal distance is 2 298.81－2 456.70 m. The paste was used for industrial filling with a mix proportion of gravel∶ copper slag tailings ＝ 6∶4, a cement dosage of 240 kg/m³, and a mass concentration of 83％. Compared with the original filling process with multi-stage pumping, the paste with this mix ratio can meet the filling demand only under the condition of single pump, and the single pump conveying distance (2 052 m) is less than the limit pumping horizontal distance, allowing for surplus power at the outlet, which verifies the effectiveness of the optimal mix ratio.

Aiming at the problem of high filling cost and poor process stability caused by insufficient tailings production in a mine, the mechanical and rheological properties of Gobi sand-tailings synergistic filling body were studied. The effects of slurry mass concentration (74％, 76％, 78％), cement-sand ratio (1∶6, 1∶8, 1∶10, 1∶12), Gobi sand content (0, 10％, 20％, 30％) and curing age (3 d, 7 d, 14 d, 28 d) on the compressive strength of filling body and the transport resistance of filling slurry were discussed. Based on the MATLAB platform, the Random Forest (RF) and Convolutional Neural Network (CNN) models were constructed to predict the compressive strength of the filling body. The results show that the uniaxial compressive strength of filling body increases with the increase of slurry mass concentration, curing age and cement-sand ratio, and increases first and then tends to be stable with the increase of Gobi sand content. The transport resistance of filling slurry increases with the increase of slurry mass concentration, and decreases first and then increases with the increase of Gobi sand content. According to the uniaxial compressive strength of the filling body and the slurry transport resistance, the optimal content of Gobi sand is 20％. In the neural network model, the prediction accuracy of the CNN model is better than that of the RF model, determination coefficient R²＝0.970 34, the average absolute error MAE＝0.101 81, and the error between the predicted value and the experimental value is 0－10.53％. The research results can provide reference for the collaborative utilization of low-grade aggregate and the reduction of filling cost in the same type of mines.

After the 1^# orebody of Kalatongke Copper-Nickel Mine was mined by the caving method, a large collapsed loose area was formed. This collapased loose area has deteriorated the mining environment of the upper ore and rock, so that the resources are difficult to be effectively recovered, and the safety of vertical shafts faces a threat. To conduct in-depth detection and treatment of this area, the loose boundary was initially determined through geological drilling and TRT advanced detection in the early stage. Due to channel blockage, traditional detection equipment could hardly access the target area. The C-ALS Gyro endoscopic three-dimensional scanning system was used to conduct detailed detection of the potential area, which clarified the location, shape and volume of the large loose area. It was found that this area only exists locally, and the overall collapse scope tends to be stable. By comparing three treatment schemes including waste rock backfilling treatment, caving surrounding rock treatment and cemented filling treatment, a comprehensive analysis of the advantages and disadvantages of each scheme was conducted. In accordance with the treatment principles, it was determined to adopt the cemented filling treatment scheme. The actual treatment effect shows that the cemented filling treatment scheme enhances regional stability, increases the resource recovery rate by approximately 30％, improves the safety guarantee level, reduces environmental impact.

In order to quantify the effects of different protective measures on the stability of jointed rock slopes, the Particle Flow Code in two-dimensions (PFC2D), strength reduction method and failure criterion characterized by a coherent fracture plane were used to reveal the failure characteristics of jointed rock slope when the parameters of contact model have been reduced until the critical rock failure state had occurred. Then the safety factor and microcrack evolution as well as energy dissipation law of jointed slopes under three working conditions including slope-cutting, anchor cable reinforcement and without any protective measures were comprehensively researched. Research shows that when the mechanical parameters have been reduced until the critical rock failure state has occurred, the main failure mode of jointed rock slope is tensile-sliding failure. The slope-cutting measure can partially improve the slope stability, and the anchor cables installed at a zone where is below the joint surface and close to the the intersection of the steeply inclined fracture and the gentle slip surface can significantly improve the slope stability. During the adjustment process to the stable state, the number of microcracks and dissipated energy generated in anchor cable-reinforced slopes are sequentially less than those in slope-cutting slopes and slopes without any protective measures. The research results can provide a reference for the slope engineering in similar open-pit mines.

To enhance the accuracy and reliability of measuring the thickness of the surrounding rock loosened zone in roadways, a high-precision prediction model (PSO-Stacking) for the thickness of the loosened zone was proposed. This model employed interpretable artificial intelligence algorithms to address the black-box effect of machine learning algorithms and explained the prediction mechanism. The model was validated through an engineering case study at Xinglongzhuang Coal Mine. By incorporating SHAP analysis to interpret model decisions, the influence of surrounding rock loosened zone characteristics was revealed, thereby improving interpretability. The research results demonstrate that the PSO-Stacking model performs exceptionally well in predicting the thickness of the loosened zone, with high prediction accuracy and minimal error. On the test set, the R² value reached 0.957, while the RMSE and MAE were 0.118 and 0.087, respectively. Global interpretability analysis of the prediction model indicates that roadway burial depth and joint development degree have the most significant impact on the prediction results. Local interpretability analysis reveals that burial depth considerably influences the thickness of the loosened zone in high-strength surrounding rock, while joint development has a lesser effect. According to the application in Xinglongzhuang Coal Mine, the average error between the predicted results and the actual values is only 4.31％, demonstrating that the proposed model can effectively predict the thickness of the surrounding rock loosened zone and reveal the influence of its characteristics. This study provides timely scientific reference for evaluating surrounding rock support and its effectiveness, meeting the demands of engineering practice.

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.

Through the true triaxial loading-disturbance tests of granite with different structural planes, the acoustic emission system was used to monitor the rock failure process, and the failure characteristics and acoustic emission evolution characteristics of rocks with different structural planes were explored. The relationship between structural surface parameters and rock sample failure outcomes was analyzed, and macroscopic and microscopic differences of the three failure results were compared. The results are concluded as follows. (1) When the length of the structural plane is 20 mm and 30 mm, the rock sample is prone to crack-induced failure. When the length of the structural plane is 50 mm, the rock sample is prone to rockburst. With the increase of the length and dip angle of the structural plane, the failure of the rock sample tends to change from shear failure to internal shear and external splitting. When the length of the structural plane is short, the dip angle has a weak influence on the failure mode of the rock sample. Structural plane grouting will weaken the intensity of rock failure. (2) The proportion of tensile and shear areas in RA-AF density diagram of rock samples with three kinds of failure results is different. (3) With different structural plane parameters, the crack distribution and amplitude exhibit significant differences in the upper, middle, and lower positions of the rock sample's structural plane. (4) Based on the analysis of the variation characteristics of the coefficient of variation CV(r) of b value and r value, it is found that there are significant differences between the formation of shear cracks and tensile cracks in granite with different structural plane parameters under dynamic disturbance. This study can provide theoretical guidance for the prevention and control of mining-induced disasters in deep rock mass with structural planes.

To reveal the influences of bedding angle and chemical corrosion under acidic environment on the mechanical behavior of carbonaceous slate, triaxial compression tests under chemical acidic environment corrosion were performed on bedding carbonaceous slate specimens collected from the side walls of large-deformation roadways. A continuous-discontinuous coupled numerical model based on the combined discrete element method (DEM) was developed, and numerical analysis under extended working conditions was conducted using the improved flexible membrane radial loading method, with results validated against physical test data. The results are concluded as follows. Under triaxial compression, the rock specimens develop inclined and penetrating fractures, accompanied by shear slip failure along the direction of the bedding angle. The corrosion of the chemical solution accelerates interlayer slip, leading to the gradual emergence and concentration of fractures. The peak strength of carbonaceous slate firstly decreases and then increases with the increase of bedding angle, reaching the minimum value especially when the bedding angle ranges from 15° to 45°. This phenomenon is mainly attributed to the wing crack propagation caused by shear slip and local stress concentration at this angle range. The chemical acidic environment significantly accelerates the structural deterioration of the slate. After 90 days of corrosion, the peak strength of the samples decreases by 36％ to 44％, and there is a negative correlation between the peak strength and the duration of acidic chemical corrosion. The research results provide a theoretical basis for the stability evaluation and support design of deep roadways.

To explore the status of safe carbon reduction in China's mining industry, the data envelopment analysis (DEA) method was used to measure the safe carbon reduction efficiency of mining industry in 30 provincial-level administrative regions of China from 2014 to 2022. Additionally, social network analysis (SNA) method was utilized to examine the spatial correlation network characteristics in detail. The results reveal that the overall efficiency of safe carbon reduction in China's mining industry exhibits a growth trend with relatively small regional disparities, indicating the green transformation of the mining industry is moving towards a balanced and coordinated safe carbon reduction direction. In terms of the spatial correlation network, while there are some interactions among provincial-level administrative regions, the overall connectivity is weak, and interaction frequency needs improvement. Further analysis shows that different regions play distinct roles in spatial spillover effects. Certain provinces occupy key positions in the network, demonstrating high centrality and significant roles as structural holes and intermediary holes. Moreover, while intra-regional connections are relatively strong, the collaborative effects between regions still have room for enhancement. The research results provide a novel perspective for comprehensively understanding the status of safe carbon reduction in China's mining industry and offers scientific guidance for optimizing policy design and promoting regional collaborative development.

In view of the contradiction between the agility of technical iteration and the lag of system renewal in the emergency system during the intelligent transformation of coal mines, an effective coordination mechanism was constructed to improve the efficiency of safety governance. Specifically, the “technology-system collaborative threshold model” was proposed, and on this basis, a multi-source data fusion framework and a “technology-system-insurance” ternary collaborative mechanism were constructed as follows. At the technology level, the federal learning was used to dynamically optimize the data weight and the OPC UA protocol unified semantics, which effectively solved the heterogeneous problem of downhole sensor protocol. At the system level, the dynamic adaptation rules of AI authority and responsibility were designed. At the insurance level, the linkage mechanism of algorithm filing and liability insurance was pioneered to systematically fill the gap of intelligent emergency system. Empirical studies demonstrate that at Yujialiang Mine, multi-source data fusion can increase operational efficiency by 80％ and reduce the false alarm rate for gas emissions to 4.3％. Meanwhile, at Hongqinghe Mine, introducing an optimization mechanism with an environmental priority coefficient, can achieve a 60％ reduction in ventilation response time. In summary, the constructed coordination threshold model and its implementation mechanisms provide a crucial quantitative tool for transforming coal mine safety governance from a passive-reactive approach to a proactive-defensive one. Furthermore, it establishes an innovative paradigm of “technology-institution-ecology” synergistic development, thereby advancing the construction of green mines.

With the increase in the mining depth of mines with high in-situ stress, the problem of low intelligence level of traditional drilling rigs has become a challenge for borehole pressure relief. To this end, an innovative design scheme for an intelligent mine pressure relief drilling rig was proposed. This intelligent drilling rig integrates four key components, including the chassis walking unit, the drilling execution unit, the support lifting unit, and the drill rod magazine unit. Among them, the unique automatic drill rod changing device realizes the flexible displacement of the drill pipe in the precision track system through the cooperation of the horizontal and the vertical pushing mechanism. With the cooperation of the fixing groove and the clamping mechanism, the automatic drill rod changing operation process can be completed efficiently and accurately, significantly improving the automation level and continuity of the operation. At the same time, the advanced in-drill information monitoring and analysis system built into the drilling rig can capture and analyze multi-source data during the drilling process in real time, laying a solid foundation for precisely adjusting the drilling parameters and promptly warning of potential risks. The overall structure of the intelligent drilling rig, as well as the structure of each unit were introduced, subsequently, based on the analysis of a large amount of drilling information, the excellent performance of the intelligent pressure relief drilling rig was comprehensively verified. Compared to the traditional drilling rigs, the operational safety of intelligent drilling rigs has been improved, equipment failure rates have been reduced, the drilling time and auxiliary operation time have been shortened, and its drilling efficiency has been improved.

Underground mine drill bit detection is a critical link to ensure the safety of underground mine operations, but existing deep learning-based detection models have shortcomings in feature extraction capability and detection efficiency. To improve detection performance, a drill bit detection model named YOLOv8-WGB based on the improved YOLOv8n was proposed. Firstly, the traditional CIoU loss function was replaced with the WIoU loss function, which enhanced the focus on key features. Secondly, the global attention mechanism (GAM) was introduced, which enhanced the global information interaction capability of the YOLOv8 backbone network, reduced information loss, and amplified global dimensional features. Finally, the BiFPN structure was added, which assigned different weights to feature maps of different scales when fusing them, so as to achieve optimal feature fusion. The test results show that YOLOv8-WGB improves precision, recall, and mAP@0.5 by 7.1%, 11.1%, and 8.3% respectively compared with YOLOv8n, and its inference speed is 173 frames/s faster than that of YOLOv8s, exhibiting higher detection speed. On the basis of maintaining the model complexity and inference speed advantages of YOLOv8n, the proposed model has significantly superior detection accuracy to YOLOv8s. It effectively balances detection accuracy and speed, and exhibits excellent performance in the underground mine drill bit detection task.

In the field of UAV-based open-pit mine surveying, most previous studies adopted only one type of UAV for data collection and analysis, without considering the issue of internal and external operation efficiency. Therefor, taking Xiangxiang Dolomite Mine as the engineering background, two types of UAVs, namely Matrice 300 RTK and Mavic 3E, were adopted. External data collection with four different flight heights was carried out in the mining area. In the internal data processing, four image control point layout schemes were selected respectively under each working condition to analyze the measuring point accuracy under different flight heights and different numbers of image control points. Meanwhile, statistical analysis of the internal and external time-consuming under each working condition was conducted, and the surveying operation efficiency of UAV-based open-pit mine was analyzed. The results show that the overall accuracy of the M300 RTK is higher than that of the Mavic 3E under the same working conditions, and as the flight heights increase, the accuracy continuously decreases. Under the working conditions of the same flight height, as the number of image control points increases, the accuracy of the two types of UAVs continues to improve, but the improvement range is not significant. Under the working conditions of the same flight height, the external time-consuming of the two types of UAVs is basically consistent, but the internal time-consuming of the Mavic 3E is only 3.8％ to 8.8％ of that of the M300 RTK. In non-coal open-pit mines with large height difference, the adoption of the Mavic 3E's real-time terrain-following flight combined with the image-control-free mode not only eliminates the field operation step of laying out image control points but also significantly reduces internal time-consuming. While ensuring accuracy, it can greatly improve the surveying operation efficiency of UAVs in mines.

The scarcity of samples seriously restricts the promotion and application of deep learning technology in the field of intelligent recognition of rock and mineral. Therefore, an intelligent incremental method for image samples of rock and mineral based on an improved deep convolutional generative adversarial network (DCGAN) was proposed. By introducing self-attention mechanism to enhance the details and authenticity of generated images, using loss function with gradient penalty mechanism (WGAN-GP) to improve training stability, expanding network structure to enhance model performance, and combining various data augmentation techniques to expand sample diversity and quality, the problem of sample scarcity has been effectively alleviated. The experimental results show that the proposed method outperforms comparative models in evaluation indicators such as peak signal-to-noise ratio, Fréchet initial distance, and structural similarity index. The loss function curves show that the model training process is stable and has a good convergence performance. The clustering analysis results indicate that images generated by the model are superior to the original images in terms of complexity and diversity. The survey results show that the model can generate high-quality and highly realistic images of rock and mineral. The research effectively alleviated the problem of scarcity of rock and mineral image samples, laying the foundation for the intelligent development and practical application of rock and mineral image generation.

A large number of iron tailings can not be fully and effectively utilized due to their low content of useful minerals, weak magnetism, fine crystal particle size and complex and difficult separation. Therefore, in order to solve this problem, a comprehensive utilization study was conducted on low-grade ore tailings from a beneficiation plant in the central Shandong region. Firstly, the properties of the original ore were analyzed, tested, and screened for analysis, and it was found that the main iron containing mineral in the original ore is magnetite. Based on the properties and characteristics of the ore, three process schemes were tested on the raw ore, namely screening－gravity concentration－medium magnetic separation－grinding－medium magnetic separation－gravity concentration process scheme (Scheme Ⅰ), screening－gravity concentration－medium magnetic separation－grinding－medium magnetic separation－flotation concentration process scheme (Scheme Ⅱ) and screening－gravity concentration－medium magnetic separation－grinding－medium magnetic separation－gravity concentration－gravity concentration－gravity tailings flotation concentration process scheme (Scheme Ⅲ). The final results show that Scheme Ⅱ has the best sorting effect, achieving a concentrate with yield of 20.46％, iron grade of 50.93％, and iron recovery rate of 44.10％. Among these ores, there are iron minerals embedded with fine particle size and closely coexisting with silicate iron minerals with relatively strong magnetism. To obtain higher grade iron concentrates, gravity separation or flotation shows obvious sorting advantages compared to magnetic separation. Therefore, Scheme Ⅱ or Scheme Ⅲ can be selected according to the actual situation.

In order to give full play to the alkali-activated reactivity of industrial solid waste raw materials, determine the degree of reaction and the type of gel formed, and optimize the mechanical properties and durability of alkali-activated cementitious materials, the effects of Ca, Fe, S, Cl, Mg and other elements on the mechanical properties, corrosion resistance and microstructure of industrial solid waste-based alkali-activated cementitious materials were summarized. The results show that the synergistic effect of Ca and S in the AACMs system complicates the reaction process. Calcium-free and low-calcium AACMs have good acid resistance, while calcium-rich AACMs are prone to decalcification under acid attack, which weakens the structural strength. Compared with the materials rich in silicon, chloride and calcium, the higher iron content has an adverse effect on the compressive strength and corrosion resistance of AACMs. The resistance to chloride ion penetration of ACCMs is related to the chloride ion binding capacity of its skeleton, the presence or absence of chlorine in the system and the pore structure. At the same time, alkaline cations also have a significant effect on the chloride ion binding capacity and resistance to chloride ion penetration of ACCMs. Finally, the problems and future development directions of alkali-activated cementitious materials were discussed, which can provide reference for further research on industrial solid waste-based alkali-activated cementitious materials.