To solve the problem of stress-structural failure that may be caused by the excavation of the right tunnel section of deep crushing station, the geological conditions of the tunnel face and the attitude information of the rock mass were collected by UAV, and the three-dimensional rock mass structure numerical calculation model of the right tunnel section of deep crushing station was constructed by combining the display discrete element numerical simulation software 3DEC. The deformation characteristics, failure mechanism and loss mode of deep rock mass under high stress conditions were explored, and the prevention measures were put forward. The results show that the stability of the surrounding rock of the tunnel section is controlled by the contact area of the red-brown granite stratum and the gray-black gray gneiss stratum and the in-situ stress field. The reason for the stress-structural failure of the tunnel section is that the excavation unloading of the crushing station leads to the formation of unfavorable blocks in the JSet #2 and JSet #3 joint groups and the excavation surface. Therefore, for the tunnel section with developed joints, the stress-structural failure disaster is a problem that needs special attention for the stability of surrounding rock after the excavation of the crushing station. It is suggested that the method of “optimizing excavation parameters + combined support form” should be adopted to systematically control the stress-structural damage after excavation unloading of crushing station from three levels of surface, shallow and deep layers.

In order to better reveal the causes of filling pipelines wearing in deep mines, 12 risk influencing factors were summarized and identified based on literature analysis, standard method and expert discussion method. Using DEMATEL (decision-making trial and evaluation laboratory) and ISM (interpretative structural modeling) integrated analysis method, through the processing of index factors data, the influence degrees of index factors and the characteristics of index causal attributes were determined, and each influencing factor was decomposed according to three stages to construct a multi-level hierarchical structure model. The results are drawn as follows. The DEMATEL-ISM method can comprehensively and objectively reflect the correlation of index factors, and the corresponding hierarchical structure can be divided into 4 layers and 3 stages. The inner diameter of the pipeline and the filling times line are the fundamental causes and key influencing factors. The absolute roughness of the pipelines, the proportion of coarse particles, the mass concentration of the slurry, the ratio of slurry flow rate to critical flow rate, and the corrosivity of the filling slurry are the transitional causes. The deflection rate, the weighted average particle size, the pipelines laying quality, the aggregate shape and so on are the direct causes. The research results can provide a theoretical reference for formulating targeted measures to prevent and reduce pipelines wearing and failure.

Daye Iron Ore is in the continuous mining stage of −270 m to −360 m middle section, the remaining ore volume in the −270 m middle section is insufficient, and the stope production capacity will be insufficient in the early stage of −360 m middle section. According to the process characteristics of the upward horizontal layered cut and filling method and sublevel drilling and stage open stoping with subsequent filling, based on the distribution of each stope, the mining process and the current situation of the mining equipment in the −360 m middle section of Daye Iron Mine, the optimization model of stope mining equipment scheduling was established. The genetic algorithm was used to simulate the most compact process arrangement, and the maximum number of simultaneous stopes was solved based on the equipment utilization function. Two schemes of single-section mining and two-section mining were proposed. The results show that when the number of stopes that can be mined simultaneously in the section of −270 m is 3, and the number of stopes that can be mined simultaneously in the section of −360 m is 5, the maximum daily production capacity reaches 4 218 t/d. The scheme of the two-section mining is more efficient, with a more stable ore production and the annual production capacity of 1.437 million tons. The two optimized mining schemes are helpful to solve the problems of insufficient production capacity and unstable production during the two-section continuous mining of Daye Iron Mine.

In order to select the best filling mining scheme and to optimize stope structure parameters of a high-value iron deposit, combined with the mining technical conditions of the deposit in the stage of −120 m to −180 m, the selection of mining scheme was regarded as a typical fuzzy decision problem. The analytic hierarchy process was used to obtain the weights of 11 indexes, and the fuzzy mathematics was used for comprehensive evaluation. The mining scheme of this iron deposit was selected as the sublevel drilling stage open stoping with subsequent filling method. Based on numerical simulation, four groups of stope structural parameters of the preferred mining scheme were optimized. The simulation results are concluded as follows. Firstly, in the process of mining, the tensile failure of each scheme is obvious, and the stress concentration occurs at the junction of the pillar and the roof. The maximum horizontal displacement of the central monitoring point at two sides of the stope and the maximum vertical displacement of the central monitoring point at the roof are 9.4 mm and 9.6 mm, respectively. Secondly, in the process of pillar mining, the shear failure of each scheme is obvious, and the maximum vertical displacement of the stope roof center in scheme Ⅱ is 28.0 mm. From the perspective of safety and economy, the optimal stope structure parameters of an iron mine are 15 m room width and 15 m pillar width. The scheme and the optimized stope structure parameters have achieved good economic benefits in mine production.

In underground metal mining, the roof stability of stope is directly related to the overall safety of the high-stage filling stope. Taking 2 types of stopes with different heights in Zhongguan Iron Mine as the engineering background, by testing the range of loose ring of pre-control top roadway without mining influence, the appropriate length of anchor rod was selected, and four kinds of combined support schemes of “prestressed long anchor cable+anchor net spray” with different row spacings were proposed. The roof stability of stope in the process of multiple mining under different anchor cable row spacing conditions was simulated and compared to determine the optimal anchor cable row spacing and other support parameters. The results show that the loose ring range of the side of the pre-controlled top roadway in the 30 m height stope is 1.6−2.0 m, and in the 60 m height stope is 1.4−2.3 m. The selected length of anchor rod is 2.4 m. When the anchor cable row spacing is 3.5 m, 2.5 m and 1.5 m respectively, the support control effect of 30 m height stope is 37.15%, 37.50% and 26.25% higher than that of no anchor cable, anchor cable row spacing of 3.5 m and anchor cable row spacing of 2.5 m respectively. When the anchor cable row spacing is 5 m, 4 m and 3 m respectively, the support control effect of 60 m height stope is 36.65%, 34.00% and 30.35% higher than that of no anchor cable, anchor cable row spacing of 5 m and anchor cable row spacing of 4 m respectively. Considering the economic cost and construction intensity, it is determined that the anchor cable row spacing of 30 m and 60 m height stope pre-control top roadway is 2.5 m and 4.0 m respectively. It is verified by engineering practice that there is no caving in the process of mining, and the stability is good. The recovery rate is 88.25% and the dilution rate is 10.39%, which can be further popularized and applied.

In response to the problem of excessive local support parameters and excessive support material consumption leading to longer support cycles and higher annual support costs in the support of roadway outside the vein in a certain lead-zinc mine, the support of roadway outside the vein in the 12-15 line of 2416 section of this mine was taken as the engineering background. After conducting rock mass quality evaluation and measuring relevant mechanical parameters by test of the rock mass, the optimal support scheme was selected by comparing the support effect and cost through numerical simulation and on-site testing. The results show that the combined support method of anchor rod+ steel plastic mesh + double reinforcement bar + shotcrete can meet the stability of the roadway outside the vein during its service life. Following parameters were selected, including the length of anchor rod with a length of 2.4 m and a diameter of 18 mm, as well as the MSCKa resin anchoring agent, with a spacing of 1.1 m, a steel plastic grid mesh specification of 4.5 m×2.5 m, a hole mesh of 6 cm, a tensile load of 60 kN, a double reinforcement bar diameter of 6 mm, and a sprayed concrete strength of 20 MPa. The support cost can be reduced by 599.46 RMB/m. The research results can provide a reference and guidance for the design of underground roadway support in similar mines.

Rock burst is the main technical challenge that troubles the safe mining of phosphate mines in the western Hubei region. In order to reduce the rock burst risk of brittle direct roof of phosphate mines in western Hubei, taking the +80 m working face of Shaqihe Phosphate Mine as the research object, the applicability of different roadway section shapes in mines with brittle direct roof was analyzed, and an inverted trapezoidal section scheme conducive to prevention and control of rock burst was proposed. Numerical simulation method was used to study the distribution characteristics of stress, elastic energy, and displacement of surrounding rocks under different section shapes, the optimal section shape was selected, and the design of relatively safe and economical section parameters were optimized. Finally, engineering verification was carried out on the working face site. The results show that for mines with brittle direct roof, the stress concentration of the roof with rectangular section is the most significant, the roof subsidence of the positive trapezoidal section is large, while the roof stress distribution of the inverted trapezoidal section is relatively uniform, and the roof stress and elastic energy are obviously released, thus reducing the risk of rock burst. Thus, the inverted trapezoidal section is the optimal section shape, with corresponding parameters of 3.4 meters for the upper bottom, 3 meters for the lower bottom, and 4 meters for the height. After optimizing the roadway section, the rock burst of direct roof on the working face has been significantly reduced. The research results can provide a successful example for the prevention and control of rock burst in similar mine roadways in western Hubei.

In order to optimize the performance of filling materials while reducing filling costs, the research on filling materials proportion was carried out. Based on the RSM-CCD method, an experiment with 4 factors and 5 levels was designed to construct a response surface regression model with factors of fly ash mass fraction A, cement mass fraction B, calcium carbonate mass fraction C, and slurry mass fraction D. The slump of the filling slurry and the uniaxial compressive strength of the filling body at 7 d and 28 d were the response values, respectively. The influence of single factor and the interaction of various factors on material properties were analyzed, and the lowest cost filling material proportion scheme was sought on the basis of meeting performance requirements. The results show that the slump of high-concentration filling slurry is only affected by a linear single factor, and the interaction has no significant effect on it. The slump increases firstly and then decreases with the increase of A, B, and C, and decreases with the increase of D. Linear and interactive effects have a significant impact on the strength of high-concentration filling body at 7 d and 28 d. There is no significant relationship between the interaction effect AC and the strength of the filling body. The increase of single factor in AB or CD will promote the strengthening effect of the other factors on the compressive strength of the filling material at 28 d, while the increase of single factor in AD, BC, and BD will inhibit the enhancement effect of the other factors on the compressive strength of the filling materials at 28 d. The optimal proportion of filling materials considering cost-effectiveness is 18.0% of fly ash mass fraction, 10.9% of cement mass fraction, 1.3% of calcium carbonate mass fraction, and 84.0% of slurry mass fraction. This proportion scheme meets the design standards for paste filling in engineering examples.

In order to meet the requirements of the two-step stope mining in the Peki Copper-Gold Mine of Serbia for the backfill strength and reduce the backfill cost, the backfill material mix ratio was optimized. The backfill strength in different parts of the stope was preliminarily determined by theoretical calculation, and several groups of indoor tests of backfill material mix ratio were carried out. The test shows that the uniaxial compressive strength of the backfill increases with the increase of the mass concentration of the backfill material and the cement-sand ratio. When the mass concentration is 68%, the cement-sand ratio is 1:6 and 1:8, the backfill strength can meet the strength requirements of the theoretical calculation. On this basis, the industrial test was carried out. The results show that the backfill strength requirements of the two-step stope mining can be met using 1:6 cement-sand ratio at the bottom of the first-step stope and 1:8 cement-sand ratio at the top and middle of the first-step stope. At the same time, compared with the original backfill ratio scheme, the backfill cost can be reduced by 2.53 yuan/t.

Most of the backfill near the mining working face are in the environment of cycle temperature. In order to study the influence of cycle temperature on the damage evolution and failure characteristics of cemented tailings backfill, digital image correlation (DIC) and acoustic emission (AE) techniques were used to conduct uniaxial compression tests on cemented tailings backfill after curing at six different cycle temperatures. The fracture process and acoustic emission behavior characteristics of cemented tailings backfill at different cycle temperatures were analyzed, and the damage model and constitutive equation of cemented tailings backfill at different cycle temperatures were established. The results show that with the increase of cycle temperature, the compressive strength, elastic modulus and peak strain of cemented tailings backfill increase first and then decrease, and all reach the maximum value when the cycle temperature is 25−40 ℃. With the increase of cycle temperature, the failure pattern of cemented tailings backfill changes from shear failure to tensile-shear composite failure, and then to tensile failure. The intensity of the acoustic emission ringing count signal in the initial compaction stage and the post-peak failure stage is different due to the different cycle temperature. The sudden change of the acoustic emission ringing count can be used as a precursor to the failure of the backfill. The reliability of the model is verified by comparing the theoretical calculation value of the constitutive model of the backfill parameters with the experimental measured value. The research results can provide reference for the design of backfill near the working face.

Aggregate size distribution of waste rock and the cement-sand ratio of backfill slurry have a significant effect on the mechanical properties of waste rock cemented backfill. In order to explore the relationship between the two and the mechanical properties of the backfill, the backfill ratio tests were carried out. The particle flow model was constructed. The laws of crack development, force chain evolution and particle failure in the process of uniaxial compression of waste rock cemented backfill were analyzed. The results show that the higher the cement-sand ratio, the higher the sensitivity of the strength of waste rock cemented backfill to the change of fractal dimension of aggregate size distribution. When the cement-sand ratio increases from 1:8 to 1:4, the strength range of samples with different fractal dimensions increases from 0.40 MPa to 1.54 MPa. In the cemented backfill, the interface between the aggregate and the cemented matrix is easy to be destroyed along the aggregate boundary and develops along the interface. With the increase of fractal dimension, the proportion of fine aggregate in the sample increases, and the proportion of shear crack increases. In addition, the higher the fractal dimension, the more conducive to the uniform distribution of the cemented matrix, which can better participate in the bearing capacity. In the design of backfill scheme, the strength of backfill can be flexibly adjusted to meet the actual needs by changing the fractal dimension of waste rock aggregate.

The porous and equal discharge technology for filling pipelines can eliminate the unattached goaf area formed by the self-flow gradient of the paste, improve the roof-contact effect of the mining site, and avoid the problem of roof subsidence. Firstly, through theoretical analysis, the head loss along the porous and equal flow discharge pipeline and the pressure head at each discharge hole were preliminarily determined, and on this basis, the diameter of the discharge hole was obtained. Then, using a self-developed porous and equal discharge test device, the influences of inlet flow rate, the number of holes, and hole spacing on the equal discharge effect were studied through experiments. Finally, numerical simulation methods were used to analyze the pressure and flow rate variations of the discharge pipeline. The results indicate that the spacing between the discharge holes has the most significant impact on the uniformity of discharge, followed by the number of holes. When the hole spacing is 14.5 cm, the flow rate at the inlet is 330 mL/h, and the number of holes is 6, the uniformity of discharge can reach up to 96%. When the paste flows in a horizontal pipe section, the static pressure of the pipeline decreases along the flow direction, and negative pressure appears at the discharge holes. The closer the discharge hole is to the inlet of the paste, the greater the pressure difference. After the paste reaches a stable state, the flow rate of each discharge hole is basically the same, and the uniformity coefficient reaches 98.8%, which means that the paste can achieve porous and equal discharge.

In the process of protective layer mining, hard rock faults and hard nodules are often encountered, which causes that it is difficult for the shearer to cut, the cutting parts are seriously worn, and the advancing speed of the working face is seriously restricted. In order to solve the above problems, based on the engineering background of Ji₁₅₋₁₇−13070 soft rock protective layer working face in Pingmei Thirteenth Mine, the mechanism of ultra-deep hole loose pre-splitting blasting was clarified. The radius range of the fracture zone in the fault hard rock was calculated to be 0.7−1.2 m. The influences of aperture and hole spacing on blasting effect were studied by numerical simulation method, and aperture and hole spacing were determined to be 94 mm and 2.0 m respectively. The technical scheme of “advance drilling in two roadways+ ultra-deep hole loose pre-splitting blasting in working face”, which can realize the parallel operation of propulsion and blasting, was put forward and the industrial test was carried out. The test results show that after adopting the technical scheme, the fault hard rock is fully broken, the wear of the shearer pick is reduced by more than 40%, the advancing speed of the working face is increased by about 25%, and the blasting pre-splitting effect is remarkable.

According to the drainage data of 7 horizontal wells in Tunlan block, the productivity characteristics of horizontal wells were analyzed. It is found that there are great differences in water production and productivity of horizontal wells. The influence of geological factors on productivity was analyzed from the aspects of coal seam buried depth, coal seam thickness and roof and floor lithology. The influence of engineering factors on productivity was analyzed from the aspects of fracturing curve characteristics, average displacement, fracturing fluid amount and sand addition. The influence of drainage factors on productivity was analyzed from the aspects of wellhead casing pressure, drainage continuity and water production. The results show that the gas production of horizontal wells is affected by the water production. In general, there is a positive correlation between the two, but too much water production will lead to a decrease in gas production. Hydrogeological conditions have an impact on the productivity of some horizontal wells. The increase of coal seam burial depth, coal seam thickness and roof mudstone thickness is conducive to the extraction of coal bed methane. The gas production of horizontal wells with low displacement fracturing is low, the fracturing fluid amount and sand addition should also be kept in a certain range, and excessive use will lead to a decrease in gas production. The descending and stable fracturing curves account for 81.4% of the horizontal well fracturing curves. The higher the proportion of the curve, the greater the gas production. In the process of drainage, the long maintenance time of the stuck pump, the decrease of the wellhead casing pressure and the high water production will reduce the gas production. The grey correlation analysis shows that the gas content of coal seam is the main controlling factor of horizontal well productivity. The research results can provide reference for the development of horizontal wells in Tunlan block.

To address the problem of pore wall instability in the fractured formation during geological drilling at Pingpo Coal Mine in Gansu Province, the mineral compositions, microstructures and pore characteristics of mud shale formation in coal measure strata were comprehensively analyzed. It is found that the clay minerals are mainly composed of illite and montmorillonite with high contents, and the degree of mineral particle cementation is low. At the same time, the large pores and medium pores account for more than 80% of the total pores volume, which is easy to cause pore wall collapse under the erosion of fluid medium. Nano materials and micro-foam agents with excellent performances were selected through laboratory experiments, and a kind of nano silicon-based micro-foam drilling fluid suitable for fractured formation drilling was developed based on the low solid content drilling fluid. The results show that the drilling fluid has a good fluidity and filtration, which can effectively suppress the deformation of coal measure strata and the collapse of pore walls, and has strong infiltration sealing performance and inhibition capabilities. Through the field application of the new drilling fluid in coal measure strata drilling, the pure drilling rate of the drilling hole was increased by 40%, the core recovery rate reached 95% and the monthly efficiency was increased by 72%, which proved that the new drilling fluid has a good wall protection and anti-collapse function in the fractured formation of coal measure strata.

The visualization of rockburst risk is of great significance to the exploitation of deep phosphate rock resources. Firstly, through the uniaxial loading test of aluminum metal, it is proved that the temperature change caused by thermo-mechanical coupling can be detected by MicroIIIS series 640 infrared thermal imager, and the increase of stress is the core reason for the increase of thermo-mechanical coupling temperature. Then, aiming at the problem that the infrared image in the actual phosphorus mine roadway is blurred and the irrelevant high temperature body intervenes to affect the effective infrared radiation characteristics information in the infrared image, the original gray image is enhanced by the adaptive gray scale stretching algorithm, so that the information entropy, histogram equalization and global contrast are optimized. The nonlinear mapping pseudo-color transformation based on temperature width adjustment is applied to enhance the visual effect of rockburst risk visual detection in actual phosphate rock roadway. Finally, through the field test of phosphate rock roadway, it is proved that the DMYB-03 handheld rockburst detector after infrared image enhancement can not only show the details of phosphate rock roadway and the infrared radiation characteristics caused by stress concentration more clearly, but also divide the stress concentration degree into stable, medium stress concentration and high stress concentration through the color brightness index of risk area and safety area. The information entropy of high stress concentration is 26.55% higher than that of stable image, the average brightness is 25.08% higher, the brightness histogram equalization is 8.36% higher, and the global contrast is 243.38% higher, semi-quantitatively reflects the degree of stress concentration of rock mass. The research results provide technical support for the visual detection of rockburst risk in mining, transportation and other fields.

On the basis of revealing the formation mechanism and development mechanism of the slope in the latent sliding zone of Shuguang Gold-Copper Mine, the treatment work of slope in the latent sliding zone was carried out. The formation factors and processes of the latent sliding zone were studied through on-site engineering geological investigation and limit equilibrium analysis. Based on engineering geological investigation, the formation factors of the latent sliding zone were divided into internal and external factors, and the formation process was divided into three stages, including the generation, development, and penetration of slope cracks. Combining the treatment conditions, a treatment scheme with large-diameter anti-slip piles has been formulated. Through engineering geological investigation and parameter back calculation, the rock mass parameters and the position of sliding surface of the latent sliding zone have been determined. Based on the residual sliding force calculation, a single row of circular anti-slip piles with a diameter of 800 mm, a length of 32 m, and a hole spacing of 4 m will be constructed on the 590 m platform. Three limit equilibrium analysis methods were used to verify the stability of the post-treatment slope, and the results show that anti-slip piles can effectively resist sliding. The research results can provide a reference for safety production and slope treatment in mines.

In order to find out the influence of water disaster in 2-3 coal seam roof mining in Gaotouyao Coal Mine, the “three-graph and double-prediction method” coupled with GIS and AHP was used to construct the water abundance evaluation model of 2-3 coal seam roof water-filled aquifer. Comprehensive comparison of FLAC3D numerical simulation, empirical formula calculation, analogy measurement and other methods, the traditional calculation formula of fractured water-conducting zone height was modified. On this basis, the classification and zoning map of water gushing (inrush) risk of 2-3 coal seam roof water-filled aquifer was obtained by compound superposition. Numerical simulation was used to predict the water inflow of Gaotouyao Coal Mine. The results show that the risk of water inrush in the central and southwest of Gaotouyao Coal Mine is higher, and the risk of water inrush in the northwest and east is lower. The normal water inflow of Gaotouyao Coal Mine is 465 m³/h, and the maximum water inflow is 558 m³/h. In view of the water disaster problems faced by the mine in the future, the feasible prevention and control measures have been put forward comprehensively.

In response to the randomness and fuzziness of water inrush risk in coastal gold mines, as well as the complex correlation among evaluation indicators, a GRA-VIKOR evaluation model of water inrush risk in coastal gold mines based on moment estimation theory was established to make the risk assessment more scientific. Firstly, 10 typical influencing factors were selected from two aspects of engineering geology and hydrogeology, and an evaluation indicator system was constructed. Secondly, four single weighting methods, namely IAHP method, G1 method, EM method, and I-CRITIC method, were used to calculate the subjective and objective weights of the indicators. Based on moment estimation theory, the integrated optimization method of subjective and objective weights was improved. According to the GRA-VIKOR principle, the risk status of water inrush was analyzed and determined by calculating the comprehensive evaluation values. Finally, the model was applied to the risk assessment of water inrush in 9 middle sections of a gold mine in Shandong Province, the risk level and ranking of water inrush in each middle section were determined. The results indicate that the evaluation results of the model are accurate and reasonable, in line with reality, and can provide reliable ideas for the risk evaluation of water inrush in coastal gold mines.

In order to improve the prediction accuracy of multi-source index risk identification in goaf, based on the particle swarm optimization (PSO) algorithm to optimize the input weights and thresholds of the extreme learning machine (ELM), a PSO-ELM method was proposed to identify the risk of multi-source indicators in the goaf. Nine indicators, including mining depth, mining method, goaf height, the maximum exposed area, the maximum exposed height, the maximum exposed span, mining pillars, measured volume, and control rate, which affect the risk of goaf in a mine in South China, were used as the main input values, and 135 measured goaf data were used as an example to predict the hazard level of goaf. The research results show that the prediction accuracy of radial basis function and traditional extreme learning machine is 88% and 92%, respectively, while the prediction accuracy of the extreme learning machine model optimized by particle swarm optimization algorithm is 96%. Compared with radial basis functions and traditional extreme learning machines, the PSO-ELM algorithm performs better on the test sets, has a better stability and generalization ability, possess good guiding significance and practicality, and is suitable for practical engineering applications.

In extensive cold region engineering, freeze-thaw failure of rock masses is a natural disaster that can’t be ignored. In order to explore the influence of freeze-thaw environment on the engineering stability of rock masses in cold regions, uniaxial compression tests were conducted on red sandstone in cold regions under different freeze-thaw cycles (0, 10, 20, 30 times) and saturation levels (0, 20%, 40%, 60%, 80%, 100%), and SEM microstructure analysis was performed on the rock specimens. The results show that with the increase of freeze-thaw cycles and saturation, the crack closure stress σ_cc, initiation stress σ_ci, damage stress σ_cd, peak stress σ_c, and frost resistance coefficient K_fm of red sandstone gradually decrease, and internal damage gradually intensifies. The failure mode of red sandstone specimens gradually changes from oblique shear failure and tensile failure to X-shaped failure, accompanied by a small amount of fragment peeled off. Recurrent freeze-thaw cycles leads to the expansion of original microcrack and the emergence of new cracks inside the rock, revealing the damage evolution characteristics of sandstone under different freeze-thaw cycles. The research results can provide a certain reference for the study of rock engineering stability and rock mechanics properties in cold regions.

To explore the damage degradation and landslide instability mechanism of weathered red-bed soft rock under the action of acid rain, the stress-seepage coupling creep test of red-bed soft rock under repeated erosion of acid solution was carried out, and the mechanical behavior and damage evolution mechanism of rock coupling creep were analyzed. By analyzing the time-strain curve of rock creep under different test conditions and the relationship between rock creep rate and permeability before and after hydrochemical damage, the mechanism of rock damage degradation under the coupling of chemical-stress-seepage and the main factors affecting rock damage were explored. The results show that the hydrochemical action will reduce the triaxial strength of the rock, with a minimum reduction of 36.31% and a maximum reduction of 48.03%. At the same time, the rock creep curve after repeated erosion by hydrochemical action is more divergent. There is a good positive correlation between rock damage law and stress level under different hydraulic conditions. The degree of hydrochemical damage is much higher than that of seepage and stress. After hydrochemical damage, rock seepage and stress will aggravate rock damage degradation. Under the action of high seepage pressure, the creep effect of rock is more obvious. Finally, the chemical damage factor is introduced to establish a triaxial nonlinear damage creep model under the stress-seepage coupling effect including chemical damage, which can describe the fluid-solid coupling creep characteristics of red-bed soft rock under the action of hydrochemical action, and the fitting effect is good.

In geotechnical engineering, instability failure often occurs in multi-layer rock mass at the same time, and its different combinations, lithology and other factors will affect the development trend of cracks. The discrete element PFC2D software was used to establish the sample model, and the uniaxial compression experiment was simulated to reveal the influence of the proportion of soft and hard rock strata on the mechanical properties, failure characteristics and energy evolution law of rock samples. The results are drawn as follows. Firstly, the proportion of hard rock in the layered composite rock sample is the main factor affecting the peak strength of the rock sample. As the proportion of hard rock increases, the peak stress of the rock sample gradually increases. Secondly, the number of microcracks and the total input strain energy of the layered composite rock sample are the minimum when the thickness ratio (R) of the adjacent rock layer is the smallest, indicating that the decrease of R will lead to the early failure of the rock sample. Thirdly, the elastic energy consumption ratio K is introduced into the energy analysis of layered composite rock samples, and it is verified that the increase of K value would be used as an early warning signal for rock deformation and failure. Fourthly, the main failure mode of the layered composite rock sample is tension-shear mixed failure, and the macroscopic cracks generally originate in soft rock part. Then, due to the sharp increase of the transverse strain of the soft rock part, the cracks penetrate into the hard rock part, revealing that the failure of the rock sample is a process of gradual loss of bearing capacity. The research results can provide a reference for practical engineering.

During the mining process of metal open-pit mines, a large amount of solid wastes such as waste rocks and tailings are discarded. Under the action of wind, sun and rain, harmful substances such as heavy metals in the wastes enter the soil, causing the soil in the mining areas and surrounding areas to be polluted. Therefore, it is of great significance to study the production, migration and enrichment of heavy metal elements in open-pit mine soil to guide the prevention and control of heavy metal pollution in mines. The types of pollution sources, soil properties and the influence of hydraulic action on the migration of pollutants in open-pit mines were introduced, and the measures to improve the risk of soil heavy metal pollution in mining areas were summarized. It points out that further research is of great significance on the influence of soil physical and chemical properties on the migration of heavy metals and establishing corresponding numerical models, and it is necessary to form a comprehensive three-dimensional heavy metal pollution prevention and control system. The study can provide a theoretical support for the control of soil pollution in mining areas.

There is a serious problem of heavy metal compound pollution in lead-zinc mining areas. Hyperspectral remote sensing technology can be used to extract heavy metals absorption characteristic spectra from soil spectral information and achieve inversion of heavy metal contents in the soil of mining areas. Based on hyperspectral data, the heavy metals contents in soil, such as Cd, Pb, As and Hg, were retrieved from the soil of the Silongduo lead-zinc mining area in Xizang. The hyperspectral data from soil samples was collected and various spectral transformations were performed, including first differential (FD), second differential (SD), logarithm of the reciprocal (AT), first differential of logarithm of the reciprocal (AFD), and second differential of logarithm of the reciprocal (ASD). The characteristic bands that are strongly correlated with the measured content of heavy metal were selected and finally four inversion models were established, including stepwise multiple linear regression (SMLR), support vector machine (SVM), artificial neural network (ANN), and random forest (RF). The coefficient of determination(R²)and root mean square error (RMSE) were selected to evaluate the accuracy of the models and the optimal inversion model for each heavy metal was obtained. The research results show that the dimensionality reduction effect and feature band selection interval of different spectral transformation methods are different. Among the five transformations, SD transformation has the best effect and can effectively distinguish feature bands, followed by ASD and AFD transformations. The RF model has the best inversion effect, with a better applicability and inversion accuracy than SMLR, ANN, and SVM. The best inversion model for As is the AT-RF model, the best inversion model for Cd is the SD-RF model, the best inversion model for Pb is the ASD-RF model, and the best inversion model for Hg is the ASD-SMLR model. The average assessment values of Cd, Pb, As, Hg content models of soil exceeded the background value of Xizang soil by 124.2, 89.8, 0.70, 1.24 times, indicating that Cd and Pb were the main pollution factors of the soil in the mine concentration area, accompanied by the combined pollution of As and Hg.

With the increase of mine depth, the heat damage becomes more and more obvious. It is difficult to meet the cooling demand of deep mines only by optimizing ventilation. The key to mine cooling by using refrigeration cycle is to choose a reasonable heat sink (cold source). Taking the demand of heat damage control in a gold mine in Guizhou as the background, based on the concept of energy tunnel, it was proposed to use the filled abandoned roadway as a cold source to receive the heat transferred from the fresh air inlet or the underground working face, so as to achieve the purpose of cooling the underground space. The thermal physical parameters of filling materials of abandoned roadway and surrounding rock were measured, and the cold source model of abandoned roadway was established. The 20-year operation was simulated, and the outlet water temperature, heat transfer power and system energy efficiency under two operating modes and three heat exchange tube layout scenarios were obtained. The results show that only by increasing the number of heat exchange tubes, the technical and economic indicators cannot be significantly improved. The intermittent operation mode can alleviate the heat accumulation of the heat sink and improve the heat transfer intensity of per unit tube length, which is conducive to the long-term stable operation of the system. According to the cooling load of the working face, the scrap power threshold is set, and the total heat storage of the heat sink within the service life is calculated. Combined with the heat transfer intensity of per unit tube length, the feasibility of different application scenarios are compared and evaluated. The research results provide a new idea for the reuse of abandoned mine space and the treatment of underground heat damage.

China's mining industry generally has the problems of high carbon emission intensity and extensive energy consumption. At present, mining is still in the theoretical level of carbon emission accounting, and there is a lack of unified management and analysis of carbon emission in the process of mining production. In view of the current situation of carbon accounting in underground mining, the existing accounting methods were summarized, and the carbon emission prediction and measurement model was constructed by using the whole life cycle assessment method and the carbon emission coefficient method, combined with the mine production management data and process equipment and other parameters. Based on this, the MVC software architecture model was used to build a system platform of carbon emission accounting for underground mining, and the function decomposition and interface design were carried out according to the six main modules of production data entry, prediction model calculation, measured model calculation, data comparison accounting, carbon perspective analysis and basic data management. Through the example application of Chengchao Iron Mine, it is concluded that in addition to high-power and high-energy-consuming process equipment such as lifting and ventilation, transportation, support and pneumatic drilling equipment are all key carbon emission points, and the error between the predicted data and the measured value is less than 10%, which meets the accuracy requirements. It shows that the constructed system can effectively realize the prediction and data analysis of carbon emissions from underground mining. The research results have guiding significance for the subsequent carbon reduction work of the mine.

Flotation wastewater treatment is of great significance to reduce environmental pollution, save water resources and promote the sustainable development of the mining industry. The present situation of treatment technology of flotation wastewater was reviewed, based on the analysis of the source, characteristics and harm of flotation wastewater, the research progress of physical, chemical and biological treatment technology of flotation wastewater was summarized. The results show that the physical methods such as coagulation-flocculation and adsorption have slow processing speed, and the removal effect of complex pollutants such as organic agents is limited. Advanced oxidation technologies such as Fenton method and ozone method are expected to become an important development direction of flotation wastewater treatment in the future because of their simple operation and high efficiency. The microbial method has a significant advantage of no secondary pollution, but it is urgent to solve the problems of long treatment time and difficult adaptation of microorganisms to the environment of flotation wastewater. In the future, different processes can be combined to form a treatment technology system of flotation wastewater for different reuse needs.

The key to prevent water outburst/gusher in coal mine is to clarify the hydraulic relationship between coal measure strata and aquifer, accurately detect the occurrence of abnormal areas, and take preventive measures in time. Based on the geological characteristics of the mining area and the evaluation of water inrush, the experimental system of coal-rock-water coupling occurrence was established to investigate the electric excitation response characteristics and signal attenuation characteristics of the medium under the magnetic field outside the borehole radar. The results show that the height of the water flowing fracture zone of the working face is 56.64 m, which exceeds the height of the water barrier. The working face is threatened by the water of the Changxing Formation aquifer and the goaf, and the risk of water inrush is high. In LCR digital bridge experiment, the dielectric constant of the medium decreases with the increase of frequency. At 100 MHz, the dielectric characteristics of the medium and the peak value of capacitance-dielectric loss(C_p−D)feature have obvious differences, and the signal transmission is stable. The resolution of borehole radar detection profile is increased at 100 MHz, and the imaging is stable. The low-resistivity anomaly area is mainly the boundary of rock strata and the water-bearing anomaly area of the Changxing Formation limestone, and some fracture zones have been found to contain water. The research results are brought into the pre-engineering consideration, and the results of geophysical exploration are further analyzed from the quantitative point of view, which provides some practical reference for similar geological water exploration work.

In response to the current challenges of low accuracy, inefficiency, poor real-time performance, and weak environmental adaptability in ore detection technology, a ore identification system based on Orange Pi was proposed. This system utilized a high-definition camera to capture real-time images of ores and processed image data using the YOLOv4-tiny-tf2 model on the Orange Pi 5B development board to achieve efficient and accurate identification of ore types. The results show that the lightweight YOLOv4-tiny-tf2 model simplifies its structure without sacrificing the accuracy of the model, which is more suitable for deployment on lower-configured devices and has a higher portability. Compared with the traditional artificial visual inspection and chemical analysis methods, the ore identification system based on Orange Pi 5B can identify the ore in real time, and the identification accuracy rate reaches 93.75%, which has high reliability and stability.

To efficiently recover copper from magnetic separation tailings of an iron mine in Anhui, the occurrence states of copper, zinc, and sulfur minerals were investigated, and the key process conditions affecting copper recovery were optimized through flotation experiments. The results show that copper with a grade of 0.10% in magnetic separation tailings is mainly present in the form of chalcopyrite, zinc with a grade of 0.37% is mainly present in the form of sphalerite, and sulfur with a grade of 3.22% is mainly present in pyrite. All minerals are fine-grained disseminated. Employing a mixed flotation-preferential copper flotation process, the optimal reagent combination of condition test is determined as follows: collector PQ-5 dosage of 70 g/t; sphalerite depressant as a combination of 400 g/t sodium sulfide, 500 g/t zinc sulfate, and 400 g/t sodium sulfite; pyrite depressant PZ-1 dosage of 300 g/t. The closed-circuit test adopted a one roughing, three cleaning, and two scavenging process, ultimately obtaining a copper concentrate with a copper grade of 20.85% and a copper recovery of 81.41%. Meanwhile, the removal rates of zinc and sulfur in the copper concentrate reaches 94.12% and 96.30%, respectively, achieving effective separation of copper from other minerals. The research results can provide valuable reference for the efficient recovery of copper from the magnetic separation tailings of this iron mine.

In order to make slag resource utilization and harmless treatment, CaO−MgO−Al₂O₃−SiO₂ (CMAS) slag glass-ceramics were successfully prepared with different additions of cadmium using glass-ceramics preparation technology with solid wastes such as tailings and fly ash as main raw materials. The crystallization characteristics of glass-ceramics with different additions of cadmium were characterized by differential scanning calorimetry (DSC), XRD, SEM, and Raman spectrum. At the same time, the bulk density, flexural strength, thermal expansion coefficient, Vickers hardness and toxicity leaching concentration of glass-ceramics with different additions of cadmium were analyzed. The results show that with the increase of cadmium addition, the full width at half maximum of the crystallization peak gradually decreases, which promotes the crystallization of the glass-ceramics, but the main crystal phase does not change significantly. The related elements in the glass-ceramics are depolymerized due to the addition of cadmium, which changes the microstructure of the glass-ceramics. In addition, the flexural strength, Vickers hardness and bulk density of the glass-ceramics increase with the increase of cadmium slag addition. The results of toxicity leaching test indicate that the maximum leaching concentration of cadmium is 0.030 37 mg/L, which is far lower than the maximum leaching concentration of hazardous waste specified by the state.

The solid waste coal gangue produced in the process of coal mining and washing and the discharge of Pb(Ⅱ) from industrial wastewater will bring great harm to the ecosystem and human health, and it is of great significance to study the efficient removal method of Pb(Ⅱ) and the rational utilization of coal gangue for ecological and environmental protection. A low-cost aminothiol difunctional modified coal gangue (CG-SHNH) composite material was prepared by grafting 3-mercaptopropyl trimethoxysilane (MPTMS) and 3-aminopropyl triethoxysilane (APTES) with coal gangue. The physical and chemical properties of the adsorbed materials were investigated by means of XRD, XRD-EDS, XFR, FTIR, SEM, Zeta potential, and so on. And it is found that new bands appeare at 2 930 cm⁻¹ and 2 560 cm⁻¹, corresponding to C—H and S—H tensile vibrations, respectively, and a new peak appeares at 3 367 cm⁻¹, which is the absorption peak of N—H bonds, indicating that the surface of CG-SHNH is rich in amino and sulfhydryl functional groups. The results of N₂ adsorption-desorption analysis indicate that the average pore size of CG-SHNH increases significantly, from 17.33 nm to 24.54 nm. The study on the adsorption performance of CG-SHNH for Pb(Ⅱ) shows that the optimal adsorption capacity of CG-SHNH for Pb(Ⅱ) is 125 mg/g when the addition amount of CG-SHNH is 1 g/L, the contact time is 20 h, the temperature is 25 ℃, the pH is 6.6, and the initial concentration of Pb(Ⅱ) is 600 mg/L. The adsorption mechanism shows that CG-SHNH amino and sulfhydryl bifunctional groups can synergistically promote the chelation adsorption of Pb(Ⅱ), exhibiting excellent heavy metal ion adsorption ability.