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Field test of high-power microwave-assisted mechanical excavation for deep hard iron ore

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 1922-1935页

作者： Feng Lin Xia-Ting Feng Shiping Li Xiao Hai Jiuyu Zhang Xiangxin Su Tianyang Tong Jianchun Song key laboratory of ministry of education on safe mining of deep metal mines Northeastern UniversityShenyang110819China Benxi Longxin mining Corporation Limited Benxi117000China

Microwave-assisted mechanical excavation has great application prospects in mines and tunnels,but there are few field experiments on microwave-assisted rock *** paper takes the Sishanling iron mine as the research object and adopts the self-developed high-power microwave-induced fracturing test system for hard rock to conduct field experiments of microwave-induced fracturing of iron *** heating and reflection evolution characteristics of ore under different microwave parameters(antenna type,power,and working distance)were studied,and the optimal microwave parameters were ***,the ore was irradiated with the optimal microwave parameters,and the cracking effect of the ore under the action of the high-power open microwave was *** results show that the reflection coefficient(standing wave ratio)can be rapidly(<5 s)and automatically adjusted below the preset threshold value(1.6)as microwave irradiation is *** using a right-angle horn antenna with a working distance of 5 cm,the effect of automatic reflection adjustment reaches the best among other antenna types and working *** the working distance is the same,the average temperature of the irradiation surface and the area of the high-temperature area under the action of the two antennas(right-angled and equal-angled horn antenna)are basically the same and decrease with the increase of working *** optimal microwave parameters are:a right-angle horn antenna with a working distance of 5 ***,in further experiments,the optimal parameters were used to irradiate for 20 s and 40 s at a microwave power of 60 kW,*** surface damage extended 38 cm×30 cm and 53 cm×30 cm,respectively,and the damage extended to a depth of about 50 *** drilling speed was increased by 56.2%and 66.5%,respectively,compared to the case when microwaves were not used.

关键词： Microwave parameters High power Field experiment Mechanical mining

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Evolution of mechanical parameters of Shuangjiangkou granite under different loading cycles and stress paths

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1113-1126页

作者： Liangjie Gu Xia-Ting Feng Rui Kong Chengxiang Yang Yuelin Xia key laboratory of ministry of education on safe mining of deep metal mines Northeastern UniversityShenyang110819China State key laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock *** this study,to reveal the mechanical parameters of deep surrounding rock under different stress paths,a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed,and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied,including the deformation modulus,elastic deformation increment ratios,fracture degree,cohesion and internal friction ***,stress path coefficient was defined to characterize different stress paths,and the functional relationships among the stress path coefficient,rock fracture degree difference coefficient,cohesion and internal friction angle were *** results show that during the true triaxial cyclic loading and unloading process,the deformation modulus and cohesion gradually decrease,while the internal friction angle gradually increases with increasing equivalent crack *** stress path coefficient is exponentially related to the rock fracture degree difference *** the stress path coefficient increases,the degrees of cohesion weakening and internal friction angle strengthening decrease *** cyclic loading and unloading under true triaxial principal stress direction interchange,the direction of crack development changes,and the deformation modulus increases,while the cohesion and internal friction angle decrease slightly,indicating that the principal stress direction interchange has a strengthening effect on the surrounding ***,the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed.

关键词： Triaxial cyclic loading and unloading test Stress path Deformation modulus and elastic deformation increment ratios Fracture degree Cohesion and internal friction angle

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Implications for fault reactivation and seismicity induced by hydraulic fracturing

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Petroleum Science 2024年第2期21卷 1081-1098页

作者： Zi-Han Sun Ming-Guang Che Li-Hong Zhu Shu-Juan Zhang Ji-Yuan Lu Chang-Yu Jin key laboratory of ministry of education on safe mining of deep metal mines School of Resources and Civil Engineering and Key Laboratory of Liaoning Province on Deep Engineering and Intelligent TechnologyNortheastern UniversityShenyang110819LiaoningChina Research Institute of Petroleum Exploration&Development PetroChina Company LimitedBeijing100084China The Exploration and Development Research Institute of Daqing Oilfield Limited Company Daqing163458HeilongjiangChina

Evaluating the physical mechanisms that link hydraulic fracturing(HF) operations to induced earthquakes and the anticipated form of the resulting events is significant in informing subsurface fluid injection operations. Current understanding supports the overriding role of the effective stress magnitude in triggering earthquakes, while the impact of change rate of effective stress has not been systematically addressed. In this work, a modified critical stiffness was brought up to investigate the likelihood, impact,and mitigation of induced seismicity during and after hydraulic fracturing by developing a poroelastic model based on rate-and-state fraction law and linear stability analysis. In the new criterion, the change rate of effective stress was considered a key variable to explore the evolution of this criterion and hence the likelihood of instability slip of fault. A coupled fluid flow-deformation model was used to represent the entire hydraulic fracturing process in COMSOL Multiphysics. The possibility of triggering an earthquake throughout the entire hydraulic fracturing process, from fracturing to cessation, was investigated considering different fault locations, orientations, and positions along the fault. The competition between the effects of the magnitude and change rate of effective stress was notable at each fracturing stage. The effective stress magnitude is a significant controlling factor during fracturing events, with the change rate dominating when fracturing is suddenly started or stopped. Instability dominates when the magnitude of the effective stress increases(constant injection at each fracturing stage) and the change rate of effective stress decreases(the injection process is suddenly stopped). Fracturing with a high injection rate, a fault adjacent to the hydraulic fracturing location and the position of the junction between the reservoir and fault are important to reduce the Coulomb failure stress(CFS) and enhance the critical stiffness as

关键词： Hydraulic fracturing Coulomb failure stress Rate-and-state fraction model Linear stability analysis Critical stiffness Seismically induced fault

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盘柔性对轴-盘转子非线性振动的影响

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Acta Mechanica Sinica 2024年第3期40卷 227-241页

作者：崔元松王延庆 key laboratory of Structural Dynamics of Liaoning Province College of SciencesNortheastern UniversityShenyang110819China key laboratory of ministry of education on safe mining of deep metal mines Northeastern UniversityShenyang110819China

在旋转机械设计中,准确预测轴-盘转子的非线性振动至关重要.在已有研究中,盘通常被视为刚体,以简化转子非线性问题.本文旨在阐明盘柔性对轴-盘转子非线性动力学响应的影响.考虑了陀螺效应和离心效应.轴基于Euler-Bernoulli梁理论并考虑v... 详细信息

在旋转机械设计中,准确预测轴-盘转子的非线性振动至关重要.在已有研究中,盘通常被视为刚体,以简化转子非线性问题.本文旨在阐明盘柔性对轴-盘转子非线性动力学响应的影响.考虑了陀螺效应和离心效应.轴基于Euler-Bernoulli梁理论并考虑von Kármán非线性,盘基于Kirchhoff板理论.利用Lagrange方程推导出了运动微分方程.采用拟弧长延拓法对偏心质量激励下的转子非线性受迫振动响应进行了数值分析.通过与已有文献的对比,验证了本文模型的正确性.探讨了盘柔性和盘位置、半径和厚度以及轴壁厚、长度对转子非线性振动的影响.结果表明,只有在非常有限的情况下,才可以忽略盘柔性,在大多数情况下,忽略盘柔性会过高估计转子的非线性振动幅值,因而使得轴-盘转子的设计偏于保守.

关键词： Shaft-disk rotor Disk flexibility Geometrical nonlinearity Vibration response Pseudo-arclength continuation method

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deep learning based water leakage detection for shield tunnel lining

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Frontiers of Structural and Civil Engineering 2024年第6期18卷 887-898页

作者： Shichang LIU Xu XU Gwanggil JEON Junxin CHEN Ben-Guo HE College of Computer Science Sichuan UniversityChengdu 610065China School of Computer Science and Engineering Northeastern UniversityShenyang 110004China Department of Embedded Systems Engineering Incheon National UniversityIncheon 22012Korea School of Software Dalian University of TechnologyDalian 116621China key laboratory of ministry of education on safe mining of deep metal mines Northeastern UniversityShenyang 110819China

Shield tunnel lining is prone to water leakage,which may further bring about corrosion and structural damage to the walls,potentially leading to dangerous *** avoid tedious and inefficient manual inspection,many projects use artificial intelligence(Al)to detect cracks and water leakage.A novel method for water leakage inspection in shield tunnel lining that utilizes deep learning is introduced in this *** proposal includes a ConvNeXt-S backbone,deconvolutional-feature pyramid network(D-FPN),spatial attention module(SPAM).and a detection *** can extract representative features of leaking areas to aid inspection *** further improve the model's robustness,we innovatively use an inversed low-light enhancement method to convert normally illuminated images to low light ones and introduce them into the training *** experiments are performed,achieving the average precision(AP)score of 56.8%,which outperforms previous work by a margin of 5.7%.Visualization illustrations also support our method's practical effectiveness.

关键词： water leakage detection deep learning deconvolutional-feature pyramid spatial attention

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Predicting microseismic,acoustic emission and electromagnetic radiation data using neural networks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 616-629页

作者： Yangyang Di Enyuan Wang Zhonghui Li Xiaofei Liu Tao Huang Jiajie Yao School of Materials Engineering Changshu Institute of TechnologySuzhou215506China key laboratory of Gas and Fire Control for Coal mines(China University of mining and Technology) Ministry of EducationXuzhou221116China School of safety Engineering China University of Mining and TechnologyXuzhou221116China State key laboratory of Coal Resources and safe mining China University of Mining and TechnologyXuzhou221116China

Microseism,acoustic emission and electromagnetic radiation(M-A-E)data are usually used for predicting rockburst ***,it is a great challenge to realize the prediction of M-A-E *** this study,with the aid of a deep learning algorithm,a new method for the prediction of M-A-E data is *** this method,an M-A-E data prediction model is built based on a variety of neural networks after analyzing numerous M-A-E data,and then the M-A-E data can be *** predicted results are highly correlated with the real data collected in the *** field verification,the deep learning-based prediction method of M-A-E data provides quantitative prediction data for rockburst monitoring.

关键词： Microseism Acoustic emission Electromagnetic radiation Neural networks deep learning Rockburst

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Paraffin–CaCl_(2)·6H_(2)O dosage effects on the strength and heat transfer characteristics of cemented tailings backfill

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International Journal of Minerals,metallurgy and Materials 2024年第1期31卷 60-70页

作者： Hai Li Aibing Jin Shuaijun Chen Yiqing Zhao You Ju key laboratory of ministry of education for Efficient mining and safety of metal Mine University of Science and Technology BeijingBeijing 100083China School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China

The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned ***–CaCl_(2)·6H_(2)O composite PCM was prepared in the *** composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were *** heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent *** results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption *** research can give a theoretical foundation for the use of heat storage backfill in green mines.

关键词： paraffin–CaCl_(2)·6H_(2)O heat transfer simulation heat calculation phase change material-based backfill latent heat of formula

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Disturbance failure mechanism of highly stressed rock in deep excavation:Current status and prospects

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International Journal of Minerals,metallurgy and Materials 2024年第4期31卷 611-627页

作者： Tao Wang Weiwei Ye Liyuan Liu Kai Liu Naisheng Jiang Xianhui Feng School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China key laboratory of ministry of education for Efficient mining and safety of metal mines University of Science and Technology BeijingBeijing 100083China Department of Engineering Science University of OxfordParks RoadOxford OX13PJUK School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

This article reviews the current status on the dynamic behavior of highly stressed rocks under ***,the experimental apparatus,methods,and theories related to the disturbance dynamics of deep,high-stress rock are reviewed,followed by the introduction of scholars’research on deep rock deformation and failure from an energy ***,with a backdrop of highstress phenomena in deep hard rock,such as rock bursts and core disking,we delve into the current state of research on rock microstructure analysis and residual stresses from the perspective of studying the energy storage mechanisms in ***,the current state of research on the mechanical response and the energy dissipation of highly stressed rock formations is briefly ***,the insufficient aspects in the current research on the disturbance and failure mechanisms in deep,highly stressed rock formations are summarized,and prospects for future research are *** work provides new avenues for the research on the mechanical response and damage-fracture mechanisms of rocks under high-stress conditions.

关键词： deep rock with high stress highly stressed rock rock failure residual stress energy release

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Excavation-induced deep hard rock fracturing:Methodology and applications

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 1-34页

作者： Xia-Ting Feng Cheng-Xiang Yang Rui Kong Jun Zhao Yangyi Zhou Zhibin Yao Lei Hu key laboratory of ministry of education on safe mining of deep metal mines Northeastern UniversityShenyang110819China

To analyze and predict the mechanical behaviors of deep hard rocks,some key issues concerning rock fracturing mechanics for deep hard rock excavations are ***,a series of apparatuses and methods have been developed to test the mechanical properties and fracturing behaviors of hard rocks under high true triaxial stress *** mechanisms of stress-induced disasters in deep hard rock excavations,such as spalling,deep cracking,massive roof collapse,large deformation and rockbursts,have been *** analytical theory for the fracturing process of hard rock masses,including the three-dimensional failure criterion,stress-induced mechanical model,fracturing degree index,energy release index and numerical method,has been *** cracking-restraint method is developed for mitigating or controlling rock spalling,deep cracking and massive collapse of deep hard *** energy-controlled method is also proposed for the prevention of ***,two typical cases are used to illustrate the application of the proposed methodology in the Baihetan caverns and Bayu tunnels of China.

关键词： Spalling deep cracking Large deformation Rockbursts Excavation-induced deep hard rock fracturing Cracking-restraint method Energy-controlled method

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Microwave response characteristics and influencing factors of ores based on dielectric properties of synthetic samples

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 315-328页

作者： Feng Lin Xia-Ting Feng Chengxiang Yang Shiping Li Jiuyu Zhang Xiangxin Su Tianyang Tong key laboratory of ministry of education on safe mining of deep metal mines Northeastern UniversityShenyang110819China

In order to understand the influence of different factors on the microwave response characteristics of ores,the effects of electrical conductivity,metal mineral content,compactness,metal mineral distribution,microwave frequency and temperature on the dielectric properties of synthetic ores(metal mineral and quartz)were *** heating tests were carried out on three types of natural ores(Hongtoushan copper ore,Sishanling iron ore and Dandong gold ore)with significant differences in metal mineral *** test results showed that under microwave irradiation,the stronger the electrical conductivity of the metal minerals,the smaller the penetration depth in synthetic *** those metal minerals with lower electrical conductivity,the microwave absorption coefficient of the synthetic samples increases with increasing metal mineral *** those metal minerals with higher electrical conductivity,the microwave absorption coefficient of the samples first increases and then decreases as the metal mineral content *** the metal minerals are distributed in layers,the penetration depth is much less than that given a uniform *** penetration depth in the sample at microwave frequency of 915 MHz is greater than that at 2.45 *** higher the electrical conductivity of metal minerals used in synthetic ores,the higher the high-temperature sensitivity of electromagnetic shielding coefficient(0.C-500.C).The Hongtoushan copper ore with high metal mineral content exhibits obvious size *** effects of ore structure and crystal particle size on the distribution characteristics of microcracks were *** on the test results,a quantitative prediction model of microwave sensitivity of ore was proposed,which provides guidance for the prediction of ore heating effect and the selection of microwave heating sequence of ore.

关键词： metal minerals Electrical conductivity metal mineral content Synthetic ore Prediction model

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