Search

In order to fully understand the current research situation in field of deep coal mining, took the relevant literature of web of science database from 2003 to 2021 as a sample, this paper made an in-depth analysis on the number of papers issued, research institutions, countries, authors, literature citations, keywords and disciplines.The results showed that China's research level is at the forefront of the world in terms of the number of papers issued, research institutions and national levels; Chinese scholars pay high attention to this field in terms of the author; highly cited documents are mostly engineering and technical studies in terms of literature citation; from the perspective of keyword development and evolution, the keywords in this field mainly focus on model, rock, numerical simulation, mechanism and stress, model and numerical simulation will be the important research methods in this field in the future.From the perspective of discipline development and evolution, disciplines in this field mainly focus on engineering, geology, multidisciplinary geoscience, energy and fuel, environmental science and ecology, sustainable development will become the hot research directions in the future.

The abundant metal minerals and geothermal resources reserved in the deep earth can provide key support for global economic development and human survival. As a subversive and unconventional mining method, the fluidized mining of deep metal ore provides an essential idea for the efficient, low-carbon, and safe development of deep resources. In view of this, we focus on metal mineral resources in the deep earth based on the uranium in-situ leaching technology; by combining the technical characteristics of the “metal mineral fluidization mining” and “deep geothermal development,” we innovatively propose the process concept of strengthening the fluidized leaching process of deep metal ore-geothermal co-mining, The idea structure and potential techniques to realize the process concept were discussed, and preliminary assumptions were given. This study mainly includes three steps: 1) investigation (such as investigating mineral properties and geothermal conditions), 2) preparation of systems (including drilling and pipeline transportation system, leaching solution and strain preparation system, geothermal utilization system, metal precipitation system, and production assistance system), 3) operation (including experimental results, optimize process parameter, and industrial utilization). Key systems, such as a dense solid mineral fluidization system, were proposed from the perspectives of mineral leaching, environmental perception, process control, energy replacement, and synergistic correlation. Key discussions were performed in five aspects: 1) the intelligent perception system for deep earth resources to solve the problems of low permeability, low penetration, premature solution preferential flow, low leaching rate, and excessive blockage, thereby decreasing the percentage of unsaturated leaching areas and effectively recycling the lower-grade minerals; 2) the seepage control system for solution in deep mining areas, divided into data acquisition, data analysis, and decision-making parts, thereby realizing efficient coordination between ground immersion environment and production information, avoiding system slowdown, and reducing heat/electric energy consumption; 3) the energy replacement system for geothermal–leaching solution, including the geological exploration and production monitoring system and ecological reclamation monitoring system, resulting in targeted adjusting the fluid flow behavior, improving capillary penetration and mass transfer; 4) the coupling system for thermal energy replacement–leaching solution circulation, which has three requirements—one is high temperature resistance, corrosion resistance and heat insulation, the second is good thermal conductivity and corrosion resistance, and the third is to be equipped with an intelligent monitoring system; 5) the thermal energy replacement-solution circulation coupling system that is based on large-scale pregnant solution container and equipped with thermal energy replacement, metal precipitation, leaching solution and strain preparation devices. Besides, the basic theoretical bottlenecks, key technical problems, and future development trends in the process of fluidized leaching–geothermal cooperative co-mining of metal ores are carefully discussed in this study. This study will provide ideas and references for enhancing the fluidized leaching process of deep earth metal ores and geothermal co-mining.

Many coal mines in China are greatly threatened by floor water inrush due to mining-induced fault activation. In this paper, a theoretical safety factor is proposed to assess fault activation during coal mining. Some critical effects on fault activation is analyzed, including fault dip angle, coal pillar width, stress concentration coefficient, and ratio of horizontal stress to vertical stress. Based on theoretical and numerical analysis, water in aquifer is very likely to burst into mining face along the fault F22 in 1000-m depth Xingdong coal mine. In addition, a new method of pre-cutting roof (PCR) is proposed to control fault activation. As the PCR angle increases, the shear stress along fault obviously decreases and the fault safety factor increases. The optimal PCR angles are greater than 75°, which is applied in the field. Field application shows that the water in aquifer did not flow into the mining face along fault F22 after PCR and the field-measured water levels in limestone-aotao is almost unchanged. [ABSTRACT FROM AUTHOR]

A study was conducted on the initial heat hazard in mines, focusing on the testing and analysis of the original rock temperature and thermal environment in deep mining areas. The results showed that the original rock temperatures in the 580 m, 650 m, and -730 m layers were 31 °C, 32.5 °C, and 34.7 °C respectively, with an average geothermal gradient of 2.45 °C/100 m in strata. The main heat sources in the working face were the surrounding rocks and electromechanical equipment, accounting for 46 % and 24% respectively. A new idea was proposed to measure the distribution of underground heat sources and the degree of heat hazard using absolute and relative heat dissipation indexes based on the total and unit lengths of ventilation tunnels. This study can provide a reference for assessing heat hazards in similar mines and implementing subsequent cooling engineering measures. [ABSTRACT FROM AUTHOR]

With the advancements in technology, the depth of underground mining of metal deposits has been increasing, which has resulted in a series of serious problems. Based on the rock mechanics work, the structural para- meters of the deep mine area of the Zhaolai gold belt were designed. Using the theoretical analysis method, empirical chart method, theoretical calculation method, and other methods, the span and length of the deep mine area of the Jiaojia Gold Mine were calculated, and the structural parameters applicable to the special stress state in the deep area were proposed. It was found that when the width of the mine area is 6 m and the height is 15 m, the length of the mine area is affected by the stability of the two sides, and the maximum length is 30 m. Considering that the average horizontal thickness of the ore body is 45 m, the size scheme is determined to be 6 m × 15 m × 22.5 m, and the mine chamber is designed to be arranged perpendicular to the direction of the ore body to ensure the stability of the mine area during deep mining. In this design process, a set of design procedures applicable to the open room mining method for the structural parameters of the mine area were formed, and taking into account the production practice of the Jiaojia Gold Mine, the structural parameters of the sublevel open room filling mining method were successfully designed. [ABSTRACT FROM AUTHOR]

The main challenges in deep mining include three highs and one disturbance, deep mine hoisting, ventilation, and intelligent mining. The poor working environment and high labor intensity of underground workers result in low production efficiency and high operating costs during the deep mining of mineral deposits, which seriously affects the safety of production underground. Taking the deep mining of a gold mine the Jiaodong Peninsula as an example, the paper analyzes it from a technical, economic, and management perspective, proposing the mechanized point-column upward horizontal layered filling mining method in the mining area. The underground working environment is effectively improved, and the production capacity of the mining area is increased by 23 %, while the mining loss rate is reduced by 20%. The resource recovery rate and production efficiency are significantly improved. Industrial experiments show that the new mining method can meet the technical and economic index requirements, and its research results can be used to guide mine production. [ABSTRACT FROM AUTHOR]

The shallow-layer resources in the Huanghebei Coalfield have been depleted, and the deep coal seam of the Taiyuan Formation (lower coal group) is the main continuous resource in mining at this stage. With the annual increase in mining depth, the exploitation of lower coal groups is being met with the influence of high ground stress, high water pressure, high temperature, and strong mining disturbances, as a result of which the threat of water inrush is particularly serious. Based on the grouting data of the coalface floor aquifer, this paper proposes an evaluation method for the control of water rushing into the coalface floor. By comparing the test data with mine electrical exploration data through ArcGIS, the results show that the water pressure threshold based on ArcGIS is twice the water pressure of the grouting reconstruction layer as the optimal solution. The research results can provide a reference for the prevention and control of water inrush in the lower coal group of Huanghebei Coalfield. [ABSTRACT FROM AUTHOR]

Copyright of BHM Berg- und Hüttenmännische Monatshefte is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Confined aquifers widely exist in the strata of the Ordos mining area. Water drainage before mining is an effective measure to avoid water inrush disasters caused by the connectivity between mining-induced roof fractures and aquifers. However, rock burst disasters occur frequently in the mining process of many water drainage working faces. The statistics show that the surrounding rock of nine water drainage working faces in five mines has suffered different degrees of rock burst, which seriously restricts the safe, efficient production and sustainable development of ten-million-ton modern mines in China. Based on this, taking the 22,106 longwall working face (LW22106) of the Shilawusu Mine, Ordos, as the engineering background, this paper investigates the occurrence mechanism of water drainage on rock burst in the roof water-rich area by using theoretical analysis, similar material simulation, microseismic measurement and other methods. The main conclusions are as follows: (1) After the drainage of the water-rich area, the pressure relief zone, pressurized zone and pressure stabilization zone are formed in sequence from the center to both sides. The width of the pressure relief zone is consistent with that of the water-rich area, and the width of the pressurized zone is about 35 m on one side. (2) When the mining is passing the pressurized zone, the coal rock mass is under the joint influence of gravity stress, mining disturbance stress and drainage transfer stress. The superimposed stress generally exceeds 2.5 times the uniaxial compressive strength (UCS) of the coal rock mass, and the maximum reaches 3.24 times, far exceeding the critical value of rock burst (1.5 times UCS), which is the main reason to induce rock burst. (3) The dynamic change in the rock burst risk areas before and after drainage in water-rich area no. 4 has been predicted, and the number of risk areas increases from 4 before drainage to 13 after drainage. Since the stress superposition effect differs due to different mining speeds, it is proposed that the dynamic regulation of mining speed in the front and at the back of the drainage area is an effective and efficient method for rock burst prevention and control. The research results will provide a theoretical basis and technical support for the prevention and control in the roof water-rich area of deep mines. [ABSTRACT FROM AUTHOR]

After coal mining enters the deep, the mining environment changes dramatically, and engineering disasters become increasingly prominent, which are mostly related to rock instability and failure. As traditional support is difficult to meet production needs, it is necessary to improve the support system. Based on the engineering background of the Pinggang mining roadway, this work studies the migration law of overlying strata in deep goaf by theoretical analysis and numerical simulation. The results show that the vertical stress and plastic failure range of the surrounding rock in front of the working face increase with the advance distance and when the working face advances to the first square, reaching the maximum. A stope spatial model considering the influence of horizontal stress is established. Combined with the theory of key strata, the stress transfer characteristics of overlying strata are analyzed. It can be seen that 0~30 m in front of the coal wall of the working face is the influence range of advanced abutment pressure, and the dynamic mining pressure in this range has a great influence. The inclined direction of the working face, 0~20 m away from the coal wall of the roadway, is the influence range of the solid coal abutment pressure. On this basis, the "migration- transfer- control" technical system of surrounding rock in deep stope face is put forward, i.e., the stress transfer of surrounding rock is caused by overlying rock migration, and the large deformation of surrounding rock is controlled by supporting means. Based on the original support scheme of the roadway, three reinforcement schemes are designed for the roof, the sidewalls, and both the roof and sides. The deformation control effect of the reinforcement scheme is far greater than that of the single factor, and the field monitoring effect is good. The research results aim to provide theoretical and technical support for the deformation control of mining roadways in the deep mining process. [ABSTRACT FROM AUTHOR]

The mining of underground coal resources often results in extensive damage to the ground surface, particularly in China, which has a large amount of coal resources. However, the laws of surface damage caused by the mining of deep and shallow underground coal resources are relatively different. This study analyzes the difference in surface damage induced by deep and shallow mining and its mechanism by field measurement and similar material simulation experiments. Surface damage is mainly manifested in the form of cracks, which can be categorized as permanent and dynamic cracks. Permanent cracks occur above the mining boundary of shallow and deep coal mines. Dynamic cracks (including dynamic stretching cracks and stepped cracks) only appear above the goaf in shallow mining. This disparity is due to the fact that strata movement in deep mining occurs in a "three zones" mode, with the failure height of strata increasing with the mining degree in an "S" shape. However, rock strata movement in shallow mining follows a "two zones" mode, with the failure height of rock strata increasing exponentially with the mining degree. Thus, the rock strata are prone to slide and become unstable in the form of benched rock beams, producing dynamic cracks, such as stepped cracks on the surface. This research improves the existing mining subsidence theory and provides technical support for relevant mines to take targeted treatment measures. [ABSTRACT FROM AUTHOR]

Abstract Compared with the traditional “dynamic‐static” load rockburst induced by working face mining, a new typical disaster with concealment characteristics has appeared in deep thick coal seam roadways, namely, static creep rockburst, the occurrence mechanism of which remains unclear. Through the method of combining theory with practice, this paper elucidated the mechanical mechanism of static creep rockburst of deep thick coal seam roadways, along with the CT inversion of its rockburst risk. Next, by establishing the creep model and three‐dimensional creep formula under static conditions, it was observed that the main conditions for the unstable creep of deep thick coal seam roadway were high stress and thick coal seam. In addition, by analyzing the unstable creep failure process of surrounding rock in static roadways, it was found that the weakening of surrounding rock strength and stress relief were the reasons for starting rockburst and reducing impedance. The mechanical conditions of creep rockburst caused by stress superposition in weak areas of the roadway under static conditions were proposed, and the criterion of rockburst possibility was given. Finally, according to the characteristics of spontaneity and time delay of such a rockburst disaster, the static creep rockburst evaluation of thick coal seam roadway before mining was achieved by CT inversion, and the research conclusions were thoroughly verified.

In geotechnical engineering, several major catastrophic accidents occur frequently in areas of high in-situ stress. To study the influence of high in-situ stress on deep mining, the in-situ stress was tested using the hydraulic fracturing method in the mine. Based on the measured data of the initial stress, a comprehensive evaluation of the stress field of the deep surrounding rocks was carried out. Combining the physical and mechanical indexes of the surrounding rocks, field measurements, and theoretical analysis, the Russenes criterion and Turchaninov criterion were applied to evaluate the propensity of rockbursts of hard rocks in the mine area. In addition, the large deformation of the soft rock in the mine was predicted based on the large deformation classification criteria. The results demonstrate that the vertical stress is linearly related to the depth. The horizontal principal stress values tested in all holes except boreholes G and I are approximately linearly distributed with depth. The greater the depth, the greater the propensity for rockburst. For obvious deviation from the maximum horizontal main stress direction of the mining tunnel, the tendency of rockburst during construction is greater. Slight deformation occurs when the tunnel surrounding rock is shallow than 660 m; larger deformation occurs when the burial depth exceeds 660 m. Level-Ⅱ or level-Ⅲ deformations may occur near the bottom of holes F, G, and I due to the lower uniaxial compressive strength of the phyllites of these holes.

It is important to classify academic papers in a fine-grained manner to uncover deeper implicit themes and semantics in papers for better semantic retrieval, paper recommendation, research trend prediction, topic analysis, and a series of other functions. Based on the ontology of the climate change domain, this study used an unsupervised approach to combine two methods, syntactic structure and semantic modeling, to build a framework of subject-indexing techniques for academic papers in the climate change domain. The framework automatically indexes a set of conceptual terms as research topics from the domain ontology by inputting the titles, abstracts and keywords of the papers using natural language processing techniques such as syntactic dependencies, text similarity calculation, pre-trained language models, semantic similarity calculation, and weighting factors such as word frequency statistics and graph path calculation. Finally, we evaluated the proposed method using the gold standard of manually annotated articles and demonstrated significant improvements over the other five alternative methods in terms of precision, recall and F1-score. Overall, the method proposed in this study is able to identify the research topics of academic papers more accurately, and also provides useful references for the application of domain ontologies and unsupervised data annotation. [ABSTRACT FROM AUTHOR]

A lead-zinc mine was originally mined using the sublevel drilling and staged open stoping method, which causes large ore loss and leaves potentially risky goafs.For the inclined medium-thick ore body in the mine, the optimization of the filling mining method was carried out.According to the actual technical and economic conditions of mining, sublevel drilling-staged open stope-subsequent filling mining method is recommended to extract the inclined medium-thick ore body in the mine.The designed stope production capacity of the mining method is 450 t/d, the ore loss rate is 22 %,the dilution rate is 13 %,the direct mining cost is 39.18 yuan/t, and the filling cost is 12.65 yuan/t.The research results have certain reference significance for the selection of mining methods for the same type of ore bodies. [ABSTRACT FROM AUTHOR]

With the increasing depth of mining in mines, the management of deep roadway ground pressure is an important guarantee for the realization of safe underground operations. In terms of the stability of the deep mining roadway in Jinfeng Gold Mine, 3 different support schemes are proposed. The 3 schemes and the original scheme are simulated using Flac3D numerical simulation software, and the 4 are analyzed from the x direction, the z direction, and the plastic zone respectively. The supporting scheme of steel mesh+resin bolt+fiber concrete was determined. And the accuracy and feasibility of the numerical simulation results are verified through the actual onsite supporting test. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of the problems existing in the underground production of gently inclined thin veins in Sanxin Gold-Copper Mine, based on the occurrence conditions of No.Ⅶ2 ore body in the Jiguanzui mining area, the mining schemes are selected. Through the analysis, it is determined that the two-step mining followed by the filling mining method is used to comprehensively mine the gently inclined thin ore body, and the different stope layout forms and mining sequences are comprehensively compared and analyzed. Finally, it is determined that the pseudo-inclined stope layout with stope perpendicular to the ore body trend is used as the mining method of the underground gently inclined thin ore vein of Sanxin Gold-Copper Mine. The scheme can realize the technical and economic indicators of a stope production capacity of about 370 t/d, a mining loss rate of about 3 %,and ore dilution rate of about 5.4 %,and safe, efficient, and economic mining, which provides favorable technical support for the mining of deep gently inclined thin veins of Sanxin Gold-Copper Mine. [ABSTRACT FROM AUTHOR]

Changba Lead-Zinc Mine uses open stope with subsequent filling. In order to implement the stope filling smoothly, it is necessary to analyze and design the filling retaining wall during stope filling. Based on the force analysis of the underground filling retaining wall, it is clear that the force of the retaining wall is closely related to the height of the filling slurry. The optimal height of the initial filling is 1.5 m, and the interval between the two fillings should be more than 24 h. When the filling height exceeds the retaining wall and the filling body accumulates to a certain strength independently at the initial setting, continuous filling can be carried out. Through the comparison of the advantages and disadvantages of similar mine retaining wall, the reinforced concrete retaining wall is determined to seal the bottom structure and stratification of open stope with subsequent filling, and wooden retaining wall to block raise connection; based on the retaining wall thickness calculation methods of compressive strength, shear strength and permeability resistance, the thickness of reinforced concrete retaining wall is determined to be 0.5 m. The concrete structure of the retaining wall is designed, realizing the construction of an underground stope filling retaining wall. The production practice proves that the design scheme of the retaining wall is safe and reasonable, and the field application results are good. [ABSTRACT FROM AUTHOR]

Deep mining has become an inevitable trend of mining development. Previously conducted studies have established that reasonable stope structure parameters are the premise to ensure the safe and efficient production of deep mines. In order to ensure the safety of deep mining, in this paper, we systematically review the existing stope structure parameter design methods, and then put forward a deep stope structure design method based on the stability of mining rock mass. Based on rock mass quality classification, this method uses a critical span graph and an improved stability graph, and fully considers the influence of joint occurrence and mining stress on the stability of surrounding rock, to design the stope structural parameters. Taking into consideration the deterioration of the quality of deep rock mass, we collect mining data at home and abroad, improve the stability graph, and make it suitable for the design of stope structural parameters with different mining methods. The design process of stope structural parameters is expounded through field engineering cases, and it has specific guiding significance for the design of stope structural parameters in deep metal mines. [ABSTRACT FROM AUTHOR]

Deep mining is an inevitable trend in the exploitation of metal resources owing to their increasing demand. The multifield coupling environment for deep mining, which includes a high in situ stress, high temperature, high hydraulic pressure, and strong disturbances from excavations, pose considerable challenges to mining safety and efficiency. Intelligent or smart mining is a key to revolutionizing the mining industry. Therefore, for promoting the intelligent transformation and upgrading of the mining industry, the study of intelligent mining technologies for deep mines has a considerable strategic significance. Based on the strategic background of mining deep resources, this study investigated future technological strategies for exploiting deep metal resources toward 2035. Global technological trends on deep intelligent mining subject to multifield couplings were analyzed using technological forecasting methods. Hot research topics and advanced technologies related to intelligent deep mining subject to multifield couplings were obtained. Based on experts’ opinions and analyses, key fundamental theories and techniques for intelligent deep mining toward 2035 were proposed. There are three promising mining methods: unconventional deep mining methods without blasting, continuous pastes backfill mining in deep mines, integration of mining, mineral beneficiation and backfill. Advanced technologies can be divided into three types: (1) smart perception of the deep mining environment, (2) intelligent working during deep mining, and (3) intelligent control of mining systems. Type 1 includes intelligent in situ stress measurements, the intelligent identification of rock mass structures, microseismic monitoring and early warning of disasters, intelligent underground space exploration, and intelligent perception of man–machine systems. Type 2 includes intelligent full-section well excavation equipment, intelligent support technology and equipment, intelligent continuous mining technology and equipment, unmanned intelligent mining equipment, and intelligent lifting technology and equipment. Type 3 includes the intelligent control of the filling system, intelligent control of the microclimate in tunnels, flexible data communication on working faces, intelligent scheduling for the entire life cycle of deep mining, intelligent scheduling of the entire mining process, integrated platform for mining management, and big data analysis for deep mining. Technological strategies, key tasks, and a technical roadmap for 2035 were proposed for intelligent deep mining subject to multifield couplings in China, including development targets and demands, fundamental research areas, and key technologies and equipment. Technological development procedures to transform deep mining technologies and improve mining intelligence were presented. Some suggestions were provided in terms of policies, industries, technologies, and talent for intelligent deep mining.

Geological hazards, such as the frequent occurrence of rock bursts in deep mining, emphasize the critical necessity for the early warning and prediction of dynamic fractures in coal and rock masses, as well as the destabilization of the surrounding rock. This study delves into the mechanisms of electromagnetic radiation (EMR) signals and their synchronous coupling with micro-seismic (ME) signals. EMR and ME signals from rock specimens were systematically collected during the uniaxial compression fracture process using a dedicated monitoring and acquisition system. Employing the wavelet analysis method, the original data underwent reconstruction and denoising, while the EMR and ME spectra, derived through fast Fourier transform, were subjected to detailed scrutiny. The comprehensive analysis unveiled that EMR signals arising from rock fractures exhibited precise timing synchronization with ME signals. Moreover, the dominant frequencies of both signals are closely aligned within the low-frequency band, indicating a remarkable degree of similarity and homology. These findings establish an experimental basis for the development of monitoring and early warning systems geared toward assessing damage to coal and rock masses using EMR and ME signals.

Due to high stress, high ground temperature, high moisture, and other factors in deep mines, the risk of coal spontaneous combustion (CSC) is enhanced, seriously affecting the safety of coal mining. To achieve early prediction of spontaneous combustion in the No. 3 coal seam at the Juye coalfield in the deep mine, this paper employs a temperature-programmed device to analyze the changing pattern of single-index gases and composite gas indices with temperature derived from the gas produced during csc. It also optimizes the index gas of coal sample spontaneous combustion. Simultaneously, the characteristics of coal temperature and a four-level warning indicator system for CSC are determined based on the analysis of indicator gas growth rate method, carbon-to-oxygen ratio, and the characteristics of the indicator gas. The composite index gases of the No. 3 coal seam in Juye coalfield are selected in the initial oxidation stage (Rco), accelerated oxidation stage (R1, G1), intense oxidation stage (R2, G1, G3), and oxidative decomposition stage (G3). This leads to the construction of a six-level warning system consisting of initial warning value, blue, yellow, orange, red, and black levels. Meanwhile, warning thresholds are also established.

In complex condition coal seam, there are a large number of geological condition parameter changes and a large range of parameter changes. The intelligent mining is the difficult problem which needs to be solved urgently at present. This paper analyzes the main geological conditions and problems of coal mines in different regions of China, and points out that compared with fully-mechanized coal mining, intelligent mining requires higher geological security. The more complex the geological conditions, the more precise the perception, the faster the analysis and decision-making, and the higher the data transmission rate of the control system. Taking the mining of 'three soft' coal seam in Huainan and Huaibei areas as an example, the problems faced in the intelligent mining process are discussed. The coal wall is frequently spalling, the scraper conveyor moves up and down, the adjacent supports are dislocated and the occlusion is not tight, the guard plates are not neat, the supports are tied to the bottom, and the advance roadway is deformed. It is pointed out that the conditions of surrounding rock (roof, floor and coal wall), coal seam strike/dip angle, rock pressure and stability of advance roadway are the five factors that affecting the normal continuous mining of the working face. In order to solve the problems caused by the above five factors, it is necessary to develop the key core technologies to solve the intelligent mining of complex working face from the aspects of surrounding rock parameter perception, trend analysis, fine control, dynamic system adaptation and self-adaptive decision-making. The application status, effect and problems to be solved in the future of the intelligent mining technology of complex conditions working face, such as the precise control and rapid follow-up technology of hydraulic support guard plate, roof partition cooperative support technology, working face equipment attitude monitoring technology, working face straightening technology, moving up and down control technology, stable pressure liquid supply control technology, simulation decision-making system platform and advance support technology, are described in detail. It is pointed out that for the coal seam with many complex conditions, the main directions of follow-up researches are the electromechanical and hydraulic integrated design of key components, distributed control mode, analysis and application of big data, cooperative rapid advancement control of equipment group, and the development of real-time simulation platform and intelligent decision-making system.

In recent years, as coal mining strategy has moved westward in China, rockburst has now become the most severely affected coal mine disaster in Ordoes area. This paper takes Hongqingliang Coal Mine in Tarangole Mining Area of Ordos coalfield as the background, and conducts a systematic study on the prevention and control of rockburst under the conditions of deep mining in Tarangole Mining Area. The research shows that the deep mining in Tarangole Mining Area is under the geological conditions of “weak cemented overburden + high strength coal”. The deep mining rock burst in Tarangole Mining Area is caused by the accumulation of a large amount of elastic energy in the hard coal body due to high-intensity mining. The prevention and control strategy of rock burst combining reducing coal strength, controlling pushing speed, optimizing section coal pillar size, and strengthening support was proposed. Hongqingliang Coal Mine adopts comprehensive measures such as drilling pressure relief, control of mining speed, and strengthening of mining roadway support. The on-site microseismic monitoring data confirmed the effectiveness of the prevention and control of rock burst and realized safe and efficient mining of the mine.

As mines go deeper and get larger, mine designs become more fragile largely due to the response of the rock mass to mining. Ground control and rock support become important levers in the mine construction schedule, production performance, and excavation health. For example, in cave mines, the production footprint together with associated mine infrastructure are significant investments in a modern caving operation. This investment must be protected and maintained to reduce the risk of ground-related production disruptions. It is necessary to preserve the health of these excavations and their maintenance through an effective rock support design. Rock support thus becomes a strategic element in asset management. This article focuses on support design for brittle ground when displacements induced by stress-fracturing consume much of the support's capacity. It deals with the functionality of the support in deforming ground. Several interlinked concepts are important when assessing excavation health. Designs must not only account for load equilibrium but also for deformation compatibility and capacity consumption. Most importantly, the support's displacement capacity is being consumed when the rock mass is deformed after support installation. Hence, it is necessary to design for the support capacity remaining at the time when the support is needed. If support capacity can be consumed, it can also be restored by means of preventive support maintenance (PSM). This concept for cost-effective ground control is introduced and illustrated on operational evidence. Furthermore, how design can impact construction costs and schedule are discussed. Support is installed to provide a safe environment and preserve an operationally functional excavation. It also must assure senior management that investments in high quality support and its maintenance will substantially reduce delays and with it, costs. It is demonstrated that the use of ‘gabion-like’ support systems can achieve these goals. A technical summary of the ‘gabion panel’ support system design is presented.

As mines go deeper, mine designs become more fragile and effective rock support becomes a strategic element for ground control to facilitate timely construction and cost-effective access for uninterrupted production. This article focuses on the design of integrated support systems for brittle ground when large displacements due to gradual bulking of stress-fractured rock or sudden violent bulking during rockbursts are induced by static and dynamic loading. It provides an overview of support design principles for a rational approach to ground control in deep mines when large deformations are anticipated near excavations. Such designs must not only account for load equilibrium but also for deformation compatibility. Most importantly, the design approach must account for the fact that the support's displacement capacity is being consumed as it is deformed after support installation. It is therefore necessary to design for the remnant support capacity, i.e. the capacity remaining when the support is needed. Furthermore, if the support capacity can be consumed, it can also be restored by means of preventive support maintenance (PSM). The PSM concept for cost-effective ground control is introduced and illustrated by quantitative and operational evidence. Contrary to other design approaches, the deformation-based support design (DBSD) approach provides the capacity of an integrated support system as a function of imposed displacements. Reduction in this support capacity due to mining-induced deformation renders excavations increasingly more vulnerable if located within the influence of active mining and seismic activity. Because deformation measurements are robust indicators of the decay in support capacity, scanning and other displacement monitoring technologies enable measurements to verify the DBSD approach, to assess the remnant safety margin of the deformed support, and to make operational support maintenance decisions.

Abstract There is great variation in the lithology and lamination thickness of composite roof in coal-measure strata; thus, the roof is prone to delamination and falling, and it is difficult to control the surrounding rock when developing roadway in such rock strata. In deep mining, the stress environment of surrounding rock is complex, and the mechanical response of the rock mass is different from that of the shallow rock mass. For composite-roof roadway excavated in deep rock mass, the key to safe and efficient production of the mine is ensuring the stability of the roadway. The present paper obtains typical failure characteristics and deformation and failure mechanisms of composite-roof roadway with a buried depth of 650 m at Zhaozhuang Coal Mine (Shanxi Province, China). On the basis of determining a reasonable cross-section shape of the roadway and according to the failure characteristics of the composite roof in different regions, the roof is divided into an unstable layer, metastable layer, and stable layer. The controlled unstable layer and metastable layer are regarded as a small structure while the stable layer is regarded as a large structure. A superimposed coupling support technology of large and small structures with a multi-level prestressed bearing arch formed by strong rebar bolts and highly prestressed cable bolts is put forward. The support technology provides good application results in the field. The study thus provides theoretical support and technical guidance for ground control under similar geological conditions.

In China, solid waste backfill technology has been used in metal mines for more than half a century. It has been essential for comprehensive excavation and utilization of mineral resources, environmental protection, and engineering safety. The core concept of solid waste filling has not changed qualitatively despite the rapid development of mining technology from semi-mechanized and mechanized automation and intelligence. It is mainly used in mine tailings, waste rock, and other solid wastes to control the hazards of goaf and tailings reservoir from the source to treat waste and hazards. However, the quality requirements, degree of fine control, and intelligent allocation technology of solid waste filling are undergoing considerable changes. Furthermore, the design philosophy of modern backfill technology consider comprehensive realization of solid waste utilization, environment conservation, mined-out area disposal, resource recovery, and ground pressure control that require optimal backfill method, sufficient mechanical strength, and pumpable backfill slurry, using information technology, automatic technology, and equipment technology. Besides, new backfill concepts are introduced, such as collaborative paste and multimaterial, synchronous, and functional backfills. In this paper, the framework of backfill mechanics was described, relying on rheology and solid mechanics. The influences of in-situ multifield factors were analyzed based on the characteristics of the in-situ stope, introducing the latest multifield coupling monitoring system. More details about the development trend and research status of critical processes in the backfill, including deep thickening, mixing, and long-distance pipe transport, have been updated. We propose a picture for the future development of intelligent backfill based on the advantages of intelligent backfill and performance of intelligent algorithms in the backfill field. In terms of the future trend of solid waste backfill, we feel that it can enrich green mining, explore the realization of modular, scale, and intelligent backfill, and actively examine and serve the needs of deep mining. Thus, the backfill method appears as the optimal choice for deep mining and green mining.

Due to the gradual depletion of shallow mineral resources at present, mines are now gradually entering the deep mining stage. To promote the safe and efficient green mining of deep coal resources and sustainable energy development, and to improve the production efficiency of paste filling mining, the research group has performed this study on the green filling mining technology and application of the working face. Taking working face 1241 (3) of the Xieqiao coal mine as the engineering background, the selection and experiment of filling materials were carried out, and the gangue, fly ash and cement produced by the Xieqiao coal mine were used as the filling aggregate. Next, the strength changes before and after paste filling was obtained by theoretical calculation. The strength at the early stage of filling was no less than 0.13 MPa, and that at the late stage of filling was no less than 2 MPa. Based on previous experimental research and theoretical calculation, the mixing pumping process of paste material ratio and the gangue crushing process were determined, and the filling pipeline system was designed. Then, based on the traditional coal mining technology, a filling mining technology of working face was designed and optimized. The field application of the research results shows that after the goaf of the working face had been filled, the ground pressure behavior of the coal wall of the working face was significantly weakened, and the stability of the surrounding rock of the working face was effectively controlled. Therefore, the method achieved good results, effectively controlled the stability of surrounding rock in goaf, and provided a theoretical basis and data support for realizing safe, efficient and green mining of deep coal resources. The results of this study bear important significance and application value.

In China, mine curtain grouting has become an important technology to ensure the safe and efficient mining of deep mineral resources and protect regional groundwater resources after more than 60 years of development and improvement. This review paper summarizes and analyzes four aspects of the current situation of curtain grouting technology in deep underground mines: curtain construction conditions, theoretical design and effects, drilling structures, and grouting materials' research and development. In addition, several main problems of curtain grouting technology in deep underground mines are analyzed: planning and construction lag behind; the theory of mine curtain grouting is not mature enough; the investigation into the mechanism of consolidation and deterioration of grout slurry under long-term high pressure is insufficient; there is a lack of research on the long-term effectiveness of monitoring and evaluation, so precise drilling control technology needs further breakthroughs. In addition, the development directions of this technology are put forward from three aspects: precise directional drilling technology; the consolidation mechanism and durability of slurry under multi-field coupling conditions; and long-term dynamic monitoring, evaluation, and early warning for grouting curtain effectiveness. In the future, mine curtain grouting will become an important mine geological guarantee technology for safety, efficiency, accurate, sustainability, and green mining of the Earth's deep resources. [ABSTRACT FROM AUTHOR]

To solve these problems of poor supporting effect and serious deformation and failure of surrounding rock of mining roadway under deep mining stress, a FLAC-3D numerical calculation model is established with −800 m level no. 2424 upper roadway in the Suncun Coal Mine as the background to compare the stress, deformation, and failure law of surrounding rock of mining roadway under once support and multi-level support with the same support strength. It is found that the multi-level support technology has obvious advantages in the surrounding rock of the horizontal roadway on the 2424 working face. From this, the key parameters of multi-level support are determined, and the field industrial test is carried out. The results show that the overall deformation of the surrounding rock is obviously reduced after multi-level support. The displacement of the two sides is reduced by about 40%, the displacement of the roof and floor is reduced by about 30%, and the plastic zone of the roadway is reduced by about 75%. The peak value of concentrated stress decreases from 98.7 MPa to 95.8 MPa, which decreases slightly. The integrity and stability of the surrounding rock are excellent, and the support effect is satisfactory. The research can provide reference and technical support for surrounding rock control of deep high-stress mining roadways. [ABSTRACT FROM AUTHOR]

To ensure the safe operation of mining equipment in the stope, it is necessary to obtain the physical environment data of the stope such as stress, strain, and displacement in the stope in real-time. The study of the generation method of the test stope environment is carried out for the scaled-up unmanned underground mining technology in Sanshandao Gold Mine. A three-dimensional laser scanner is used to scan and obtain the point cloud data and colored image information of the spatial form of the test stope. After processing, the space environment of the test stope is obtained;the stope environment perception device is used to connect multiple types of fiber grating sensors to complete the cluster of real-time collection and storage of physical environment data within the test stope, and then the mining environment within the operating stope is obtained. Based on the change of physical environment data of the mined stope, a prediction model that can quickly predict the change of the physical environment of the adjacent stope is established, which can play a guiding role in the safe operation of mining equipment and the safe production of the test stope. [ABSTRACT FROM AUTHOR]

With increasing depth, the multi-rope friction hoister system is widely used in deep vertical shafts. However, due to the mechanical performance difference, manufacture errors and operational characteristics of the hoister system, the force between steel ropes does not balance during the operation of the system, causing a slide of part of the steel ropes, leading to more hoister system maintenance workload and shortening the life of steel ropes. In light of these problems, based on the mechanism of unbalanced force between steel ropes, in the case study of Chener Gold Mine, type selection calculation of initial rope suspension device in deep shafts is carried out to select the proper initial suspension device. With it, the maintenance operation changes from once every other week to once or twice every year, and the life of steel ropes can basically reach 2 a. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Resources is the property of Geology & Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ground pressure increases obviously with the mining depth in mines.Sanshandao Gold Mine uses pipe joint bolt for supporting, which is hampered by insufficient tensile pull-out force and perishable bolts.In light of that, experimental study on hydraulic expansion bolt reinforcement and support technology is carried out.The action mechanism of the hydraulic expansion bolt is deeply analyzed.The numerical simulation analysis of the supporting effect of hydraulic expansion bolts in roadway surrounding rock was carried out, and the influence laws of bolt row spacing, bolt spacing, and the number of bolts in each row on the characteristics of stress, deformation, and plastic zone of roadway surrounding rock were compared and analyzed.The support design scheme was applied in the field, and the support effect was monitored and evaluated.The test shows that the tensile pull-out force of pipe joint bolts is 20-30 kN.When the hydraulic expansion bolt is pressurized to 12 MPa, the tensile pull-out force can reach about 100 kN.After pressure relief, the tensile pull-out force is still significantly higher than that of the pipe joint bolt, indicating that the hydraulic expansion bolt can better squeeze and strengthen the surrounding rock, provide strong support resistance and ensure the bolting effect. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Geotechnical issues due to inappropriate support designs of underground drift will affect mining developments and production. The aim of this study was to provide a systematic support design method for deep hard-rock drifts in China. Field investigations and laboratory studies were carried out on the engineering geological properties of the rock masses along drifts in the Sanshandao Gold Mine. Potential wedge analysis and safety factors were determined using Unwedge software. The rock mass properties and support requirements were analyzed accordingly using different rock mass classification systems; then, an updated combined support system including rock bolts, wire mesh, and shotcrete was proposed. Numerical methods were used to quantify the plastic zone and principal stress of the drift, the plastic zone was reduced, and the rock stress state was improved after installing the support systems. Field monitoring data also confirmed that the updated support system prevented excessive rock mass deformation in drift. This study provides a reliable method for deep hard-rock drift support at Sanshandao Gold Mine and will also be helpful for the optimization of subsequent support. [ABSTRACT FROM AUTHOR]

With the depletion of shallow coal resources, the existing production mines in Fengfeng Mining Area have entered the era of deep coal mining. Deep coal mining will face the problems of high ground stress, high temperature, high karst water pressure, complex water conduction structure and strong mining disturbance. All kinds of new problems and new characteristics of water inrush are gradually emerging, showing different hydrogeological laws from shallow mining. Based on the analysis of 72 water inrush cases in Fengfeng Mining Area over the years, the water inrush types are divided by single factor and the water inrush modes are summarized by multiple factors. According to the recharge source of water inrush source and the spatial relationship between coal seam exploitation and water inrush aquifer and channel, the water inrush types are divided into 7 categories, 28 subclasses and 50 types. At the same time, the paper systematically summarizes the various factors of disaster causes, analyzes the manifestation of water inrush from multiple angles, sums up 9 kinds of water inrush modes based on different key disaster causing factors, and illustrates the main characteristics and mechanism of water inrush modes combined with typical water inrush cases.

The existing research on rock bursts in goaf roadway mainly focuses on the static load caused disaster. However, there is few research on the dynamic load superimposed disaster mechanisms based on static load. In terms of the dynamic load stress wave response of the surrounding rock of the roadway, the damage mode of the roadway is not related with the stress wave disturbance and its mechanical effects. In order to solve this problem, taking 3-1103 working face in Ordos mining area, Inner Mongolia as the research object, the study analyzes the impact damage characteristics of the goaf roadway and the dynamic and static load sources of the rock burst. The goaf roadway is under the 'F' type overburden rock structure on the side of the goaf, and the source of static load is the superimposed stress field of the lateral concentrated support stress and the advanced mining concentrated support stress of the working face. The source of dynamic load is the initial pressure of the basic roof, periodic pressure and the near-field mine earthquake formed by the square area break and the far-field mine seismic release energy. The combined effect of dynamic and static load under the impact roof rock layer can easily induce impact disaster in roadways with different stress fields under high ground stress and stress concentration. The FLAC3D numerical simulation method is used to analyze the stress state of the impact roadway under the dynamic and static load sources of the goaf roadway and the impact of the stress wave of the mine earthquake, and to verify and analyze the field impact damage characteristics in comparison. The numerical simulation results have a strong consistency with the field damage characteristics. During the goaf compaction process, the maximum vertical concentrated stress is transferred from the coal pillar to the side of the roadway side, and the bolt axial force shows an asymmetrical distribution state. During the dynamic load process, the principle stress difference of the roadway surrounding rock is repeatedly loaded and unloaded, the peak particle velocity (PPV) value of the stress wave on the front wave side is larger than that on the back wave side. The shallow stress wave of surrounding rock is reflected and superimposed, the PPV value is consistent with the maximum displacement of the shallow part of the surrounding rock after dynamic load. The surrounding rock of the goaf roadway forms the difference in stress field between the side of the roadway and the coal pillar side as well as the difference in dynamic load stress field in the process of dynamic and static load. According to the damage characteristics of goaf roadway under dynamic and static load and the results of its numerical simulation and validation analysis, the separate source prevention and control measures of static load decompression and load reduction, dynamic load earthquake reduction and energy dissipation are formulated. The measures are roof hydraulic fracturing, roof and floor blasting decompression, decompression of large-diameter boreholes of roadway and reinforcement of roadway surrounding rock. These measures are used to prevent the accumulation of elastic energy of thick and hard roof, weaken the amplitude of stress wave, and improve the surrounding rock stress environment. After taking pressure relief measures, the measured microseismic energy is released in the form of small energy level and multiple frequency. The total microseismic energy is reduced by 49.2% compared with that before pressure relief, the proportion of microseismic small energy events below 103 J increases from 75% before pressure relief to 89%, the static load of the field roadway surrounding rock is reduced, and there was no sudden change of stress when dynamic and static load are superimposed, which has proved the effectiveness of impact prevention and control measures.

To study the deformation and failure law of roadway surrounding rock with weak interlayer under dynamic and static loads, taking the deep transportation roadway of Longfeng Coal Mine as the research object, the mechanical deformation characteristics of roadway surrounding rock with weak interlayer under dynamic and static loads is analyzed by using FLAC3D numerical simulation software, and the support optimization scheme is proposed combined with the actual roadway situation on site. The results show that the influence of dynamic load on roadway both sides is greater than that of roadway roof and floor. Compared with the static load, the deformation and failure range of roadway surrounding rock under dynamic load is more sufficient, the weak interlayer is easier to separate from the adjacent rock stratum and a dangerous area with caving risk is formed in the roadway roof. The stability of surrounding rock is obviously improved under the new support measures, which ensures the safe production of the mine.

Coal-bearing rocks are inevitably exposed to high temperatures and impacts (rapid dynamic load action) during deep-earth resource extraction, necessitating the study of their mechanical properties under such conditions. This paper reports on dynamic compression tests conducted on coal-bearing mudstone specimens at real-time temperatures (the temperature of the rock remains constant throughout the impact process) ranging from 25 °C to 400 °C using a temperature Hopkinson (T-SHPB) test apparatus developed in-house. The objective is to analyze the relationship between mechanical properties and the fractal dimension of fractured fragments and to explore the mechanical response of coal-bearing mudstone specimens to the combined effects of temperature and impact using macroscopic fracture characteristics. The study found that the peak stress and dynamic elastic modulus initially increased and then decreased with increasing temperature, increasing in the 25–150 °C range and monotonically decreasing in the 150–400 °C range. Based on the distribution coefficients and fractal dimensions of the fractured fragments, it was found that the degree of damage of coal-bearing mudstone shows a trend of an initial decrease and then an increase with increasing temperature. In the temperature range of 25–150 °C, the expansion of clay minerals within the mudstone filled the voids between the skeletal particles, resulting in densification and decreased damage. In the temperature range of 150–400 °C, thermal stresses increased the internal fractures and reduced the overall strength of the mudstone, resulting in increased damage. Negative correlations between fractal dimensions, the modulus of elasticity, and peak stress could be used to predict rock properties in engineering.

Deep rock formations in extreme environments are characterized by complex working conditions, various structures, high hardness, and high resistance to compression. However, existing coring techniques leave the cores of deep rock formations vulnerable to residual stresses, resulting in poor fidelity during deep coring. This paper develops a rock-breaking model for the structural parameters of drill bits. It proposes that a drill bit’s structural parameters in terms of back-rake and side-rake angles will affect the core’s fidelity performance. In addition, the core’s mechanical specific energy and maximum stress will reflect the fidelity effect. The accuracy of the theoretical model was verified via simulation analysis. The simulation results show that the tool’s average cutting force and Standard deviation of cutting force increase as the drill bit’s back-rake and side-rake angles vary. This leads to increased shear friction on the core, which affects the maximum stress and mechanical specific energy, and, subsequently, the fidelity of the core. The back-rake angles ranged from 15° to 25°, with the optimum back-rake angle of 21° producing a maximum stress and a mechanical specific energy that were 0.69 and 0.85 times higher than the highest point, respectively. The side-rake angles range from 5° to 15°, with the optimum side-rake angle of 10° producing a maximum stress and a mechanical specific energy that were 0.76 and 0.96 times higher than the highest point, respectively. The finite element method error was 1.21%. This work’s main results will help reveal the fidelity mechanisms of the drilling process and contribute to the development of fidelity drill bits for complex surface drilling processes.

The compressive deformation of backfill materials is large due to the large mining depth of coal seams and high mining-induced stress during the deep backfill mining. Therefore, the controlling effect on strata movement significantly differs from that in shallow coal seams. The research aims to explore the influences of the compressive deformation of backfill materials on the strata movement and stress evolution in deep backfill mining. For this purpose, the backfill panel in Xinjulong Coal Mine, Shandong Province, China was taken as an engineering case study; the changes in displacement, structural evolution, and stress distribution of overlying strata in the panel under compression ratios of backfill materials of 70%, 40%, and 20% were investigated. In addition, the influences of different compressive deformations of the backfill materials on the controlling effect on overlying strata were compared and investigated. The results showed that the displacement of overlying strata in the backfill panel decreases with the decreasing compression ratio: the maximum displacement of overlying strata decreases from 24.32 to 13.74 and 6.83 mm as the compression ratio is reduced from 70 to 40%, and 20%, respectively. Relative to the overlying strata at a compression ratio of 70%, the vertical displacements at compression ratios of 40 and 20% separately decrease by 43.5 and 71.9%. The lower the compression ratio of backfill materials, the better the control of overlying strata. The results provide theoretical support for optimizing the performance of backfill materials in deep backfill mines and controlling the ground pressure in the stope. [ABSTRACT FROM AUTHOR]

Compared with the traditional "dynamic‐static" load rockburst induced by working face mining, a new typical disaster with concealment characteristics has appeared in deep thick coal seam roadways, namely, static creep rockburst, the occurrence mechanism of which remains unclear. Through the method of combining theory with practice, this paper elucidated the mechanical mechanism of static creep rockburst of deep thick coal seam roadways, along with the CT inversion of its rockburst risk. Next, by establishing the creep model and three‐dimensional creep formula under static conditions, it was observed that the main conditions for the unstable creep of deep thick coal seam roadway were high stress and thick coal seam. In addition, by analyzing the unstable creep failure process of surrounding rock in static roadways, it was found that the weakening of surrounding rock strength and stress relief were the reasons for starting rockburst and reducing impedance. The mechanical conditions of creep rockburst caused by stress superposition in weak areas of the roadway under static conditions were proposed, and the criterion of rockburst possibility was given. Finally, according to the characteristics of spontaneity and time delay of such a rockburst disaster, the static creep rockburst evaluation of thick coal seam roadway before mining was achieved by CT inversion, and the research conclusions were thoroughly verified. [ABSTRACT FROM AUTHOR]

In order to study the deformation evolution law of fault activation caused by deep mining in Shizishan Copper Mine, China, a monitoring system for fault activation slip is designed and implemented on the basis of the field investigation of footwall fault activation of the main orebody in the mining area. The displacement and stress of the fault are monitored by the multipoint displacement meter, bolt stress meter, and borehole stress meter. According to the measured results, the activation deformation laws of fault F2, fault F3, and fault F4 during deep continuous mining are analyzed in detail. The results show that, when the influence range of underground mining spreads to the fault, the increase in the additional tensile stress on the fault plane will reduce the shear strength of the fault and increase the slip of the fault. When the shear stress exceeds the shear strength of the fault plane, the shear failure of the fault plane occurs, the rock mass on both sides of the fault loses stability, and the fault becomes active; when the orebody in the deep sublevel 14 and sublevel 15 were continuously stoped, the development of the mining influence area to fault F2 leads to fault F2's activation. When stoping the orebody in sublevel 16, fault F3 also activates. With the continuous downward mining of the deep part, the slip amount increases continuously. The fault activation sequence is from fault F2 to fault F3, and then to fault F4. [ABSTRACT FROM AUTHOR]

Copyright of Secretary (16742354) is the property of Secretary Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Mining Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)