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Effects of aggregate size distribution and carbon nanotubes on the mechanical properties of cemented gangue backfill samples under true triaxial compression

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 311-324页

作者： Qian Yin Fan Wen Zhigang Tao Hai Pu Tianci Deng Yaoyao Meng Qingbin Meng Hongwen Jing Bo Meng Jiangyu Wu state key laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China state key laboratory of mining Response and Disaster Prevention and Control in Deep coal Mines Anhui University of Science and TechnologyHuainan 232001China state key laboratory for Geomechanics&Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing 100083China key laboratory of Xinjiang coal resources Green mining Ministry of EducationXinjiang Institute of EngineeringUrumqi 830023China

The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious ***,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of *** mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically *** results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,***,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the ***σ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite ***ε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse *** increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure.

关键词： cemented gangue backfill materials particle size distribution true triaxial compression test carbon nanotubes mechanical properties failure modes

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Correlation between the rock mass properties and maximum horizontal stress:A case study of overcoring stress measurements

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 39-48页

作者： Peng Li Meifeng Cai Shengjun Miao Yuan Li Yu Wang key laboratory of Ministry of Education for Efficient mining and safety of Metal Mines University of Science and Technology BeijingBeijing 100083China state key laboratory of coal resources and safe mining China University of Mining and TechnologyXuzhou 221116China

Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress *** investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution *** results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with *** is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and ***,there is no obvious relationship between the rock quality designation(RQD)and *** maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same *** addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.

关键词： overcoring stress measurements elastic modulus Poisson's ratio rock quality designation maximum horizontal stress fuzzy identification

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Mesomechanism of steel fiber reinforcement and toughening of reactive powder concrete

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Science China(Technological Sciences) 2007年第6期50卷 815-832页

作者： JU Yang JIA YuDan LIU HongBin CHEN Jian state key laboratory of coal resources and safe mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China

Reactive powder concrete (RPC) is a novel cement-based composite material with ultra-high strength. Embedding a certain amount of short steel fibers in the matrix can improve the RPC’s toughness and overcome the disadvantage of high brittle- ness. In this paper, a number of direct uniaxial tension tests have been carried out with ‘8-shape’ RPC200 specimens. The bond-slip process, mesoscopic structural variation and mechanical characteristics of a fiber pullout of the matrix have been investigated using the real-time SEM loading system and CCD observation tech- niques. The influence of the volume of embedded short steel fibers in matrix on the mesoscopic morphology of attachments on the surface of a pulled individual fiber, the initial cracking force, the ultimate pullout force, interfacial bond strength and the pullout rupture energy have been analyzed. A general formulation relating these quantities to the volume of fibers in matrix has been proposed. The components comprising the interfacial bond strength have been outlined. In addition, the con- tribution that fibers make to enhance and toughen the reactive powder concrete has been discussed. It is shown that there exists an optimal threshold of fiber volume ρv, opt =1.5% at which the bond performance of a fiber pullout of RPC be- haves best.

关键词： reactive powder concrete, steel fiber, interfacial bond strength, reinforcement and toughening, mesomechanism

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Experimental investigation on the reformation and strength weakening of hard limestone by acidizing

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International Journal of mining Science and Technology 2022年第5期32卷 965-979页

作者： Bingxiang Huang Mingxiao Hou Xinglong Zhao Yuekun Xing state key laboratory of coal resources and safe mining China University of Mining and TechnologyXuzhou 221116China

Several derivative disasters such as ground pressure disasters and methane explosions can be caused by the hard roof in coal *** limestone roofs with fine integrity and extreme hardness,collapse is difficult and the effect of conventional roof control methods is *** reformation is an effective way to weaken the strength of roof strata based on acid-rock *** this study,the rock strength damage law and acid reaction characteristics were tested by the limestone acidification ***,the strength degradation mechanism of limestone under the acidity effect was *** results show that the acid corrosion characteristics of limestone are obvious,as numerous mineral grains generate voids under the effects of acid corrosion,and more defects are formed *** acid-rock reaction is the most intense at the early stage and then gradually reaches dynamic equilibrium,and the acid corrosion rate of limestone is 4.24%(10%HCl,360 min).The hard limestone is damaged after ***,the internal cracks can be induced to rapid initiation and unstable propagation under load,which reduces the strain required for rock failure by 33.33%.The failure morphology is more complicated,and the uniaxial compressive strength and elastic modulus decrease by 52.42%and 34.44%*** strength weakening of hard roof after acidification is due to the defects such as intergranular cracking caused by the corrosion of rock crystals under acidity effect,which accelerate the initiation and propagation of internal cracks with external ***,acidification induced the deterioration of rock mechanical properties by reforming the roof *** feasibility of acidizing reformation method to control hard roof is confirmed in this study.

关键词： Hard roof Acidizing reformation Strength weakening Acid-rock reaction Corrosion

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Longwall surface subsidence control by technology of isolated overburden grout injection

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International Journal of mining Science and Technology 2017年第5期27卷 813-818页

作者： Xuan Dayang Xu Jialin state key laboratory of coal resources and safe mining China University of Mining&TechnologyXuzhou 221116China

Surface subsidence is a typical ground movement due to longwall mining, which causes a series of environmental problems and hazards. In China, intensive coal extractions are commonly operated under dense-populated coalfields, which exacerbates the negative subsequences resulted from surface settlement. Therefore, effective approaches to control the ground subsidence are in urgent need for the Chinese coal mining industry. This paper presents a newly developed subsidence control technology: isolated overburden grout injection, including the theory, technique and applications. Relevant procedures such as injection system design, grouting material selection, borehole layout, grout take estimation and injection process design are proposed. The applicability of this technology has been demonstrated through physical modelling, field measurements, and case studies. Since 2009, the technology has been successfully applied to 14 longwall areas in 9 Chinese coal mines. The ultimate surface subsidence factors vary from 0.10 to 0.15. This method has a great potential to be popularized and performed where longwall mining are implemented under villages and ground infrastructures.

关键词： Longwall mining Subsidence control Isolated overburden grout injection Green mining

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Risk evaluation of rock burst through theory of static and dynamic stresses superposition

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Journal of Central South University 2015年第2期22卷 676-683页

作者：李振雷窦林名王桂峰蔡武何江丁言露 state key laboratory of coal resources and safe mining(China University of mining and Technology) School of Mines China University of Mining and Technology

Rock burst is one of the most catastrophic dynamic hazards in coal mining. A static and dynamic stresses superposition-based(SDSS-based) risk evaluation method of rock burst was proposed to pre-evaluate rock burst risk. Theoretical basis of this method is the stress criterion incurring rock burst and rock burst risk is evaluated according to the closeness degree of the total stress(due to the superposition of static stress in the coal and dynamic stress induced by tremors) with the critical stress. In addition, risk evaluation criterion of rock burst was established by defining the "Satisfaction Degree" of static stress. Furthermore,the method was used to pre-evaluate rock burst risk degree and prejudge endangered area of an insular longwall face in Nanshan coal Mine in China. Results show that rock burst risk is moderate at advance extent of 97 m, strong at advance extent of 97-131 m,and extremely strong(i.e. inevitable to occur) when advance extent exceeds 131 m(mining is prohibited in this case). The section of two gateways whose floor abuts 15-3 coal seam is a susceptible area prone to rock burst. Evaluation results were further compared with rock bursts and tremors detected by microseismic monitoring. Comparison results indicate that evaluation results are consistent with microseismic monitoring, which proves the method's feasibility.

关键词： rock burst hazard mining stress risk evaluation microseismic monitoring

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Development and verification of large deformation model considering stiffness deterioration and shear dilation effect in FLAC^(3D)

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International Journal of mining Science and Technology 2018年第6期28卷 959-967页

作者： Wang Ruijie Li Chong Xu Jinhai Pan Lijin School of Mines China University of Mining and Technology key laboratory of Deep coal Resource mining (CUMT) Ministry of Education state key laboratory of coal resources and safe mining China University of Mining and Technology

The existing constitutive models of rock with strain softening cannot successfully reflect the damageinduced anisotropy and nonlinearity of the post-peak failure behavior under progressive loading. In order to better reflect the nonlinear stress-strain behavior of rock, especially for the post-peak failure behavior,with expected stiffness degradation and large deformation, a modified constitutive model of rock considering stiffness degradation and dilatation behavior at large deformation was proposed in this study. This study analyzes and discusses various attenuation parameters in the proposed nonlinear plastic constitutive model using FLAC^(3D) software. The excavation-induced stress in rocks was calculated by FLAC^(3D) using the Mohr-Coulomb model, conventional strain model, and the proposed modified model. The obtained results of these models were analyzed and compared with field data. This study shows that the simulated results using the proposed new constitutive model matched much more closely with the measured field data, with an average error less than 5%. This new model can successfully reflect the damage-induced stiffness degradation at large deformation, and can provide a theoretical basis for stability design and evaluation of underground excavation.

关键词： Stiffness degradation Dilatancy behavior Nonlinearity Post-peak failure behavior Deep soft rock roadway FLAC^3D

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Pressure-relief and permeability-increase technology of high liquid–solid coupling blast and its application

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International Journal of mining Science and Technology 2014年第1期24卷 45-49页

作者： Hao Zhiyong Zhou Chao Lin Baiquan Pang Yuan Li Ziwen state key laboratory of coal resources and safe mining China University of Mining & Technology

As for the coal seam with high stress,high gas and low permeability,a single technology cannot prevent the complex dynamic *** of this,the study proposes a new method of pressure-relief and permeability-increase technology of the high liquid–solid coupling *** coal seam injection and charging structure change,the paper fully works out the dual functions of the water and *** the theoretical calculation,numerical simulation and physical experiments,we obtained that the initial blasting stress,displacement and overpressure of the liquid–solid coupling blast are much better than that of ordinary *** technology has been used in the relative coal mine,and the application results show that the technique has effectively prevented the coal and gas outburst,which has a wide range of application.

关键词： High stress High gasLow permeability coal seamLiquid-solid coupling blast

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Evaluation of La_(0.7)Ca_(0.3)Cr_(0.95)Zn_(0.05)O_(3-δ)-Gd_(0.1)Ce_(0.9)O_(2-δ) Dual-phase Material and its Potential Application in Oxygen Transport Membrane

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Journal of Materials Science & Technology 2014年第10期30卷 954-958页

作者： Tenglong Zhu Zhibin Yang Minfang Han Union Research Center of Fuel Cell State Key Laboratory of Coal Resources and Safe MiningChina University of Mining & Technology

In this work, a dual-phase material consisting Gd0.1Ce0.9O2-δ （GDC, 60 wt%） was synthesized. of La0.7Ca0.3Cr0.95Zn0.05O3-δ （LCCZ, 40 wt%） and Properties including phase structure, sintering behavior, electrical conductivity and oxygen permeability for LCCZ-GDC were evaluated. The results show that dense LCCZ-GDC dual-phase disks were obtained at the sintering temperature of 1250, 1300, 1350 and 1400 ℃ by tape casting and high temperature sintering method. The grain sizes of both GDC and LCCZ grew up with the increasing of sintering temperature. The average grain size of GDC was about 0.5, 0.8, 1.4, 1.8 μm while the average grain size of LCCZ was about 0.8, 1.5, 1.8 and 2 pm after sintering at 1250, 1300, 1350 and 1400℃, respectively. Oxygen flux of LCCZ-GDC decreased with the increase of sintering temperature from 1250 to 1400 ℃. The oxygen flux of LCCZ-GDC sintered at 1250 ℃ reached 0.079 mL/min/cm2 at 975℃ with a membrane thickness of 800 μm. Dual-phase material of LCCZ-GDC will be a promising oxygen transport membrane material for its low sintering temperature and good microstructure.

关键词： Dual-phase material Tape casting Sintering temperature Oxygen transport membrane

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Unsteady temperature field of surrounding rock mass in high geothermal roadway during mechanical ventilation

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Journal of Central South University 2017年第2期24卷 374-381页

作者：张源万志军顾斌周长冰程敬义 School of Mines China University of Mining and Technology key laboratory of Deep coal Resource mining of Education Ministry China University of Mining and Technology state key laboratory of coal resources and safe mining China University of Mining and Technology

To explore the spatial-temporal evolution law of rock mass temperature in high geothermal roadway during mechar^ical ventilation, a series of experiments were conducted based on the physical simulation test system of thermal and humid environment in high geothermal roadway, which is a method independently developed by China University of mining and Technology. The results indicate that during ventilation, the disturbed region of the temperature extends gradually from shallow area to deep area in the surrounding rock mass of the roadway. Meanwhile, the temperature increases as the exponential function from shallow area to deep, with steady decrease of the temperature gradient and heat flux. As the ventilation proceeds, the relationship between dimensionless temperature and dimensionless time approximately meets Hill function.

关键词： high geothermal mine heat hazard unsteady temperature field evolution law mechanical ventilation

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