CHINA MINE ENGINEERING

Abstract:This paper introduces the different classification system of mineral resources and mineral reserves, and summarizes their main classification standards and the main reporting code in the capital market. At the same time, this paper briefly introduces the typical classification standards and reporting code, and briefly analyzes and explains the main characteristics of mineral resources and mineral reserves in the capital market.

Abstract:In order to improve the safety and reliability of coal mine gas control system, a safety assessment system for coal mine gas control system is established, utilizing the improved fuzzy hierarchical analysis method and entropy weight method to determine the subjective and objective weight of each indicator respectively, and then, according to the principle of information entropy minimization, the weight results obtained by the two methods are combined to obtain the complex weights, which overcomes the problem of determining unreasonable weight by a single assessment method. A mine in Guizhou Province is taken as the practice object, through the process of “qualitative-quantitative-qualitative”, the safety of the coal mine gas control system is qualitatively assessed, and based on the calculated results, the corresponding rectification suggestions are put forward for the existing problems in the mine, which has high practical value for the assessment and improvement of the safety of coal mine gas control system.

Abstract:On the background of coal seam water injection and dust prevention of Yangquan No.2 Coal Mine, it is found that in the construction process of high pressure water injection to wet the coal seam, the water entering the coal pore and fracture can drive away the gas from the macro level and realize competitive adsorption with the original adsorbed gas from the micro level. On the basis of the above, this paper conducts experimental research on the coal gas desorption with different water content and different water injection volume. The results indicate that there is a functional relationship between the water content and the gas adsorption limit. The desorption amount of gas-containing coal body increases with the increase of water injection, and the effect of gas displacement by water injection is obvious.

Abstract:There are many advantages in pass drawing, but there are also some hidden dangers which affect its application. When the shaft is filled with ore, the shear stress of the shaft wall can be reduced, and the wear damage caused by collision and rolling on the shaft wall can be eliminated. The friction and wear caused by the shaft filling with ore can eliminate the impact of the unloading ore on the ore in shaft, and the cohesion of the ore in shaft is basically stable, reducing the probability of blockage due to arch forming in the shaft. Pass drawing when the mine shaft is full is an important measure to eliminate hidden danger.

Abstract:Magnesite mineral resources are abundant in China and widely used downstream, and it has a greater space for optimization in development and utilization. In this paper, the distribution and overall development of magnesite resources are analyzed. In the past period of time, there were some problems in Chinese magnesite mining industry, such as low comprehensive utilization rate of resources caused by disordered mining, backward technology and insufficient overall level of green development, and low-level blind expansion and slow progress of transformation and upgrading of the industry, which seriously restricted the development of the industry. In view of the above problems, the countermeasures and suggestions are put forward to promote the green and high quality development of magnesite mining industry: firstly, build green and intelligent mine, to economically and intensively utilize magnesite resources; secondly, improve the technological level of the whole process,to develop high value-added products; thirdly, strengthen the complementary chain, extension chain and strong chain of the industrial chain, to consolidate the foundation for development; fourthly, improve the level of project access, to promote the standardized and orderly development of the industry.

Abstract:Huashugou copper mine is located in the deep of iron deposit, so its geological structure is complex. In order to master the occurrence process and rules of ground pressure dynamic disaster in Huashugou copper mine, a set of microseismic monitoring system is built in it. The design of microseismic monitoring system is a key step, because the layout of the network will affect the positioning accuracy of microseismic events, and then affect the monitoring effect. In this paper, the main ground pressure hazard area of the mine is obtained by field investigation and rock mechanics analysis. Based on this area, the optimal monitoring design scheme is obtained by using the network design tool, and the design effect is tested by field verification. The results show that the optimal design of microseismic network can greatly improve the accuracy of ground pressure disaster warning.

Abstract:In order to study the damage effect and accurately obtain the disturbance of drift advancement blasting on surrounding rock, sonic wave test method is used in this paper to detect the surrounding rock damage in the process of drift advancement blasting. According to the results of the sonic wave test, the parameters that can effectively reflect the characteristics of damage are extracted, and the blasting sound velocity and blasting damage results are calculated according to the formula, so as to directly reflect the surrounding rock damage. Based on the ultrasonic test of the blasting using ordinary explosive cartridge and cutting seam cartridge, the sound velocity changes in the charging section and the plugging section are obtained, according to which the damage of blasting to the surrounding rock is obtained.

Abstract:This paper takes an open-pit mine as the research object, adopts the three dimensional limit equilibrium method to carry out the stability analysis of the slopes in each area of the mine, realizes the solution of the safety factors of each area through SLOPE2000 software, and further puts forward the suggestions of slope angle optimization. At the same time, the software uses the simulated annealing algorithm to search for the most dangerous sliding surface of slope failure in each area, and a three-dimensional sliding surface model is established by the modeling software and the analysis of it is conducted. The applied research shows that the results obtained by adopting three dimensional limit equilibrium method are more realistic in the calculation of slope stability coefficient of open-pit mine; and the results that the most dangerous sliding surface searched and simulated by the simulated annealing method have certain applicability, which is convenient to guide the correct landslide treatment of slope.

Abstract:In order to study the problems of floor pressure relief and gas control in the mining of close-distance coal seam group, by analyzing the development mechanism of floor rock pressure relief and plastic zone, the numerical simulation was used to analyze the effect of floor pressure relief and permeability enhancement after the mining of upper protective layer. and the effect of gas control in the mining of protective layer of close-distance coal seam group was verified through engineering practice. The results show that after the mining of the protective layer. the maximum failure depth of the floor rock layer can reach 17.8m, which is greater than the maximum vertical distance of 17 m between No.5 coal seam and No.9 coal seam, and No.9 coal seam is within the protection range. Through numerical simulation. the maximum depth of plastic zone of floor rock failure is 23m; after the working face of No.5 coal seam advances and exceeds the pressure measuring location, the gas pressure of the pressure measuring hole decreases by 46%~57.9%. indicating that the outburst risk of No.9 coal seam within the effective protection range of No.5 coal seam after mining has been eliminated. and the pressure relief effect is good.

Abstract:The plastic zone of the surrounding rock of the roadway is directly related to its deformation and damage. The numerical simulation model is established based on the collapse degree of the overlying rock in the goaf which is obtained by the theoretical analysis. Based on the mechanical mechanism of the stress transfer in the goaf, the paper studies the damages on the regional stress field and the roadway surrounding rock plasticity under the two different modes of gob-side entry driving and gob-side entry retaining. The study shows that under different modes, the roadway stress field is related to the surrounding rock strength, with small maximum principal stress value difference. However, under the channel stress field, the surrounding rock in the plastic zone has different deterioration degrees with the time differences. The study results have certain reference value for the roadway layout.

Abstract:Severe deformation of surrounding rock in deep and large-section roadways affects the mining efficiency of coal mines. The main reason is that the burial depth increases and the surrounding rock stress is too large, which leads to the inability of traditional support measures to meet the requirements. For the above problems, the combined bolt-grouting technology is proposed for support, and two construction techniques of hollow grouting bolts are expounded. The numerical simulation method is used to analyze the stress and strain of the roadway surrounding rock under the traditional end bolt anchoring measure and the hollow grouting bolt anchoring measure. After the implementation of the on-site combined support measures, the effect is investigated, and the following conclusions are obtained: ① The ultimate pull-out stress of the end hollow grouting bolt anchoring is greater than that of the expanding hollow grouting bolt anchoring. The former is 1.5 times the ultimate pull-out stress of the latter; ② Numerical analysis shows that the traditional end bolt anchoring technology is used in the deep part. The maximum displacement of the roof is 140mm, and the roof is seriously damaged; For the hollow grouting bolt anchoring, the maximum displacement of the roof is 60mm; So the hollow grouting bolt anchoring technology has better supporting effect. ③ After comparison between the traditional support measures and the combined bolt-grouting support measures, it’s found that the maximum displacement in the deep part of the traditional bolt anchoring support area is 420mm, and the maximum displacement in the deep part of the hollow grouting bolt anchoring area is 120mm. The hollow bolt-grouting anchoring technology has obvious supporting effect. The research results show that the combined grouting-bolt support technology can effectively control the serious deformation of the surrounding rock in the large-section roadway.

Abstract:According to the complex geology and production technical conditions of the 201 and 203 working faces of a mining company, the No.2 coal seam is mined by the comprehensive machinery. FLAC3D is used to numerically simulate the stress distribution and the deformation and damage of the surrounding rock in the mining area during the mining of the 201 and 203 working faces. The numerical simulation results of the 201 and 203 working faces at different stages are taken as the research object. The distribution characteristics of the displacement field, stress field and plastic zone are analyzed, and the appearance rule of the mine pressure in different stages of the working face is revealed.

Abstract:In order to study the crustal stress and displacement changes during the rock cross-cut coal uncovering, the corresponding numerical simulation Is carried out with FLAC 3D software. From the perspectives of stress distribution and displacement changes, the coal dynamic response in the process of rock cross-cut coal uncovering is studied and the influence of the crustal stress and displacement changes on the mine gas outburst disaster is analyzed, so as to provide references for similar mines to prevent gas outburst accidents occurrence during the rock cross-cut coal uncovering. The research results show that there is a close relationship between the working face stress concentration and the rock cross-cut excavation distance in the process of rock cross-cut coal uncovering. The stress concentration phenomenon is easy to occur in the two sides of the roadway at 2~8m, and it increases with the decrease of the vertical distance from the coal seam to be uncovered. The stress peak value is 23.83MPa under coal covering and the roadway is seriously deformed and damaged; The rock cross-cut coal uncovering is likely to cause redistribution of stress on the roadway roof and floor, with significantly increased deformation. When the vertical distance from the 3# coal seam is 0~5m, the maximum deformation is 72.22cm, which is easy to cause the roof collapse and bottom bulge, so as to induce coal and gas outburst accidents.

Abstract:RQD grading is widely used to evaluate the integrity of rock mass. The traditional RQD grading method uses manual measurement for operation, with high labor intensity and low work efficiency. To solve this problem, this paper takes Julong Copper Mine as the engineering background and proposes a RQD grading method based on Image J analysis function. As for the method, firstly shoot the drilling core image to obtain the drilling core information, number the drilling cores of different lengths with Image J, get the core lengths of different numbers by the measurement and analysis function, and at last calculate the RQD value. The drilling core cataloging is completed quickly. The error between the calculation results and the results obtained by the traditional RQD grading method is only 0.5% to 1.0%, with good consistency and high accuracy. The method is convenient and efficient, and is suitable for practical engineering applications, especially in plateau areas and areas with heavy conditions.

Abstract:On the basis of Shendong Mining Area, following the principle of obtaining local materials, for theissues of local resources rational development and utilization and the project construction costs reduction, this paper proposes the experimental study on the workability of ultra-fine sand concrete, and the influence of different fly ash ratios on the compressive strength of ultra-fine sand concrete, which is of great significance for the innovative application of fine sand concrete technology. The study shows: ① the correlation between the different proportions and workability of ultra-fine sand concrete; ② the influence of different fly ash ratios on the slump degree of ultra-fine sand concrete; ③ the mechanism of influence of different fly ash ratios on the compressive strength of ultra-fine sand concrete.

Abstract:Steel headframe is a core structure of mine hoist system. Currently, first-order elastic analysis has remained the widely used method for steel structure stability design. The current standards only stipulate the value range of calculated length coefficient of the steel headframe diagonal braces without giving specific solution method. Euler’s formula and buckling analysis can be used to solve calculated length coefficient of diagonal braces. The analysis software MIDAS GEN is used to perform linear buckling analysis on the headframe model in actual projects, with the procedure of solving calculated length coefficient introduced in detail, which can provide reference for similar projects.

Abstract:Digitization is the necessary way to achieve high-quality development of traditional mining enterprises. Now, the intelligent development of mines in China is still faced with problems such as difficulty in capturing information with data deluge, poor reliability of multiple heterogeneous data real-time transmission, high delay in equipment remote operation, and low efficiency of intelligent decision-making based on big data. The fifth-generation (5G) mobile communication technology for vertical industry and industrial communication wireless solutions, with its features of high reliability, short time delay and wide connectivity, provides an opportunity to solve the above problems. Based on the application requirements of today’s digital transformation of mines and the technical advantages of 5G, this paper proposes typical scenarios for intelligent innovation applications in mines and integrates the application with virtual reality, big data, cloud computing, and artificial intelligence.

Abstract:In order to study the kinetic characteristics of coal under impact damage, the impact damage test under different strain rates is carried out on coal samples with the 50 mm diameter split Hopkinson pressure bar test system. The results show that the fragmentation process can be divided into four stages, namely the compaction stage, the linear elastic stage, the crack propagation stage and the damage stage. Under different strain rates, the strain of the coal sample increases with time. The larger the strain rate, the greater the strain-time curve slope of the coal sample; The dynamic deformation modulus and dynamic compressive strength of the coal increase with the increase of strain rate, and fluctuate within a certain range; There is a clear correlation between the coal sample impact crushing block distribution and the strain rate.