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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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Deformation mechanism and NPR anchor cable truss coupling support in tunnel through fault fracture zone

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Journal of Mountain Science 2025年第1期22卷 354-374页

作者： HUO Shusen TAO Zhigang HE Manchao WANG Fengnian XU Chuang State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China

To address the issue of extensive deformation in the Tabaiyi Tunnel caused by the fault zone,nuclear magnetic resonance(NMR)technology was employed to analyze the physical and mechanical properties of waterabsorbing *** analysis aimed to understand the mechanism behind the significant *** from the principle of excavation stress compensation,a support scheme featuring NPR anchorcables and an asymmetric truss support system was *** validate the scheme,numerical analysis using a combination of the Discrete Element Method(DEM)-Finite Element Method(FEM)was ***,similar material model tests and engineering measurements were carried *** experiments were also performed to evaluate the NPR anchor-cable and truss support system,focusing on anchor cable forces,pressures between the truss and surrounding rock,pressures between the initial support and secondary lining,as well as the magnitude of settlement and convergence deformation in the surrounding *** results indicate that the waterinduced expansion of clay minerals,resulting from damage caused by fissure water,accelerated the softening of the mudstone's internal structure,leading to significant deformations in the Tabaiyi Tunnel under high tectonic *** original support design fell short as the length of the anchor rods was smaller than the expansion depth of the plastic *** a result,the initial support structure bore the entire load from the surrounding rock,and a non-coupled deformation contact was observed between the double-arch truss and the surrounding *** adoption of NPR asymmetric anchor-cable support effectively restrained the expansion and asymmetric distribution characteristics of the plastic *** the mechanical degradation caused by water absorption in mudstone,the rigid constraint provided by the truss proved crucial for controlling the stability of the surrounding *** research findings hold significant implicatio

关键词： Fault fracture zone Large deformation Nuclear magnetic resonance NPR anchor cable truss support Coupled simulation

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Collaborative pollution and carbon reduction behaviors of carbonated Pb-contaminated soil stabilized with a low-carbon binder derived from waste concrete

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Journal of Rock Mechanics and geotechnical engineering 2025年第3期17卷 1770-1785页

作者： Fangyuan Mu Zhiqiang Ji Lei Lang Zihan Ma Wei Zhang Zhaorong Zhang Jiang-Shan Li State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Department of Civil Engineering Yantai UniversityYantai264005China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science Wuhan430071China

Due to the limited hydration capacity,solidification/stabilization(S/S)with waste concrete powder(WCP)has a low *** can reduce carbon dioxide(CO_(2))emissions and improve strength of lead-contaminated soil,but its mechanism and environmental behaviors are *** light of this,a comprehensive study was conducted on the compressive strength,lead immobilization,conductivity characteristics,and carbonation mechanism of carbonated Pb-contaminated soils stabilized with WCP compared to calcining 600℃*** indicated that with carbonation,the compressive strength of the samples was significantly improved at the early stage(1 d),resulting in increased unconfined compressive strength(UCS)by 2.5-5.2 times due to the filling of pores by *** negatively affected the lead immobilization capacity of highly doped(30%)samples,while this effect reversed after 3 d of carbonating due to the reduced alkaline *** lead immobilization capacity decreased after 28 d of carbonating due to the cracking of samples and the influence of a lower pH on the solubility of lead-carbonated hydroxide((PbCO_(3))_(2)Pb(OH)_(2)).The water evaporation(saturation<16.8%)led to dry shrinkage cracking and decreased UCS of the *** on this finding,a conductivity model was developed for carbonated and cured samples,accurately predicting changes in saturation levels(R^(2)=0.98).A relationship between conductivity and UCS or lead immobilization capacity was *** research proposed an innovative method for the reduction of CO_(2)emission as well as laid down a theoretical basis for the recovery of WCP and lead-contaminated soils through carbonation.

关键词： Waste concrete powder(WCP) Carbonation Lead-contaminated soil Microstructure Conductivity model

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Evolution of the elastic properties of lacustrine organic shales under different thermal maturity conditions

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Science China Earth Sciences 2025年第3期68卷 781-802页

作者： Zhenjia CAI Luanxiao ZHAO Jiqiang MA Fengshou ZHANG Jianhua GENG State Key Laboratory of Marine Geology Tongji UniversityShanghai 200092China School of Ocean and Earth Science Tongji UniversityShanghai 200092China Department of Geotechnical Engineering College of Civil Engineering Tongji UniversityShanghai 200092China

Research on the elastic responses of organic-rich shales during thermal evolution has predominantly focused on North American marine shales. However, the rock physics properties of lacustrine(continental) organic-rich shales with varying maturities, particularly under the unique geological conditions in China, have not yet been comprehensively explored. Therefore,characterizing the elastic properties of lacustrine organic-rich shales across various maturity stages is crucial for understanding their seismic rock physics responses and for enabling the identification of sweet spots in continental shale reservoirs using logging and seismic data, as well as facilitating geophysical monitoring of the in-situ conversion of oil shales. In this study,hydrous pyrolysis experiments were conducted on immature shales from the Chang 7 member of the Yanchang Formation in the Ordos Basin and the Jijuntun Formation in the Fushun Basin. Compressional and shear wave velocities, along with elastic anisotropy, were measured at various stages of thermal maturity to observe the evolution of the elastic properties. For the Chang7 shale(compacted shale), both P-and S-wave velocities perpendicular to the bedding decreased significantly during the oil and gas generation stages, with the S-wave velocity perpendicular to the bedding decreasing by over 40%. Meanwhile, the elastic anisotropy increased significantly, likely because of microcracks formed by hydrocarbon expulsion from the bedding-parallel organic matter. In contrast, the Jijuntun Formation shale(cemented shale) exhibited an increase in both P-and S-wave velocities during the oil generation stage. This trend could be attributed to early-stage cementation, which suppressed microcrack formation, while the increase in the elastic modulus of the organic matter became dominant. However, during the gas generation stage, both velocities decreased, while the anisotropy increased owing to the growth of organic pores and microcracks, which out

关键词： Lacustrine shales Thermal pyrolysis Elastic wave velocity Anisotropy In-situ conversion

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Induced mechanism of tunnel rockbursts based on dynamic buckling of rock plates

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Geohazard Mechanics 2025年第1期3卷 15-27页

作者： Deng, Jian Gong, Yanglin Li, Shaojun Department of Civil Engineering Lakehead University Thunder Bay P7B 5E1 Canada State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China

Rockburst, characterized by a sudden and violent rock failure resulting in the expulsion of rock from its surroundings, poses a significant threat to the safety of tunnel excavation operations, often causing property damage and injuries to workers. Buckling has been identified as a critical mechanism leading to rockbursts. Seismic events or blasting can induce rockbursts when stress waves reach the free surface of underground openings. This paper aims to investigate the induced mechanism of tunnel rockbursts based on the dynamic buckling of rectangular rock plates. As a rock stress wave approaches a tunnel sidewall, it decomposes into perpendicular and parallel component loads relative to the free surface. The perpendicular stress reflects off the free surface, forming a rectangular thin plate of rock. The parallel stress triggers parametric resonance in the plate, resulting in a tunnel rockburst. An illustrative example of tunnel sidewall rockbursts in Jinping II hydropower project, China, is provided to study the effects of stress wave amplitude and frequency, static and dynamic components, rock damping, multiple frequencies, and vibration modes. Based on this mechanism analysis, recommendations are proposed to mitigate the risk of tunnel rockbursts. The research offers a plausible explanation for the heightened frequency and severity of rockbursts in Tunnel Boring Machine tunnels compared to New Austrian Tunneling Method tunnels at the Jinping II project for the first time. © 2025 The Author(s)

关键词： Dynamic buckling Plates Rockbursts Stress waves Tunnels

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Corrigendum to “Mechanical behaviors of backfill-rock composites: Physical shear test and back-analysis” [J rock Mech Geotech Eng 3 (2024) 807–827]

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Journal of Rock Mechanics and geotechnical engineering 2025年第2期17卷 1285-1286页

作者： Jie Xin Quan Jiang Fengqiang Gong Lang Liu Chang Liu Qiang Liu Yao Yang Pengfei Chen State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China School of Civil Engineering Southeast UniversityNanjing211189China Energy School Xi'an University of Science and TechnologyXi'an710054China

The authors regret that in the paper of Xin et al.(2024),a bug was found in the used numerical *** concerns one of the damage coefficient that was incorrectly updated during the calculation *** a consequence for some fluctuation scales,the bug had a limited impact on the found constitutive ***,the conclusions given in the paper are still *** authors have re-analyzed all the constitutive model results presented in the paper and the corrected Table 9,Eqs.(19)and(20),and Fig.18 in the original paper are shown as follows.

关键词： rock process constitutive

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Applicability of existing criteria of rockburst tendency of sandstone in coal mines

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International Journal of Mining Science and Technology 2025年第3期35卷 417-431页

作者： Tianqi Nan Linming Dou Piotr Małkowski Wu Cai Haobing Li Shun Liu Jiangsu Engineering Laboratory of Mine Earthquake Monitoring and Prevention Xuzhou 221116China School of Mines China University of Mining and TechnologyXuzhou 221116China State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources Xuzhou 221116China Department of Geomechanics Civil Engineering and GeotechnicsAGH University of Krakow30-059 KrakowPoland

To evaluate the accuracy of rockburst tendency classification in coal-bearing sandstone strata,this study conducted uniaxial compression loading and unloading tests on sandstone samples with four distinct grain *** tests involved loading the samples to 60%,70%,and 80%of their uniaxial compressive strength,followed by unloading and reloading until *** parameters such as the elastic energy index and linear elasticity criteria were derived from these ***,rock fragments were collected to calculate their initial ejection kinetic energy,serving as a measure of rockburst *** classification of rockburst tendency was conducted using grading methods based on burst energy index(WET),pre-peak stored elastic energy(PES)and experimental ***-class classification and regression analyses were applied to machine learning models using experimental data to predict rockburst tendency levels.A comparative analysis of models from two libraries revealed that the Random Forest model achieved the highest accuracy in classification,while the Ada Boost Regressor model excelled in regression *** study highlights that on a laboratory scale,integrating ejection kinetic energy with the unloading ratio,failure load,W_(ET)and PES through machine learning offers a highly accurate and reliable approach for determining rockburst tendency levels.

关键词： Burst energy index Pre-peak stored elastic energy Ejection energy of rock fragments Machine learning Rockburst tendency classification

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Fe/N modified porous carbon nanofibers with encapsulated FeCo nanoparticles for efficient electrocatalytic nitrate reduction to ammonia

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Journal of Environmental Sciences (China) 2025年 157卷 90-99页

作者： Chen, Jiayu Wu, Anni Li, Jixiang Hong, Chengyi Tang, Wenxiang Zheng, Hu Teng, Wei State Key Laboratory for of Pollution Control and Resource Reuse College of Environmental Science and Engineering Tongji University Shanghai 200092 China Department of Geotechnical Engineering College of Civil Engineering Tongji University Shanghai 200092 China Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 200120 China University of Chinese Academy of Sciences Beijing 100049 China Department of Civil and Environmental Engineering Carnegie Mellon University PittsburghPA15213 United States Key Laboratory of Geotechnical and Underground Engineering of the ministry of Education State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai 200092 China

The efficient electrocatalytic nitrate (NO3−) reduction to ammonia (NRA) offers a sustainable alternative for both environmental remediation and ammonia synthesis. Developing advanced electrocatalysts with rationally designed spatial arrangement of active sites and optimizing the synergetic effect among components are crucial for high efficiency and selectivity. Herein, we present Fe/N active sites decorated on porous carbon nanofibers (CNFs) with encapsulated FeCo nanoparticles (FeCo@CNFs-Fe/N) as electrocatalysts for NRA. The FeCo@CNFs-Fe/N catalyst demonstrates exceptional performance, achieving a high ammonia yield of 498.18 μmol/(h·gcat). Meanwhile, the enhanced reduction activity, especially the reduction in overpotential by 0.565 V, is 3–10 times higher than that of FeCo-encapsulated and Fe/N-modified CNFs-based catalysts. The enhanced catalytic activity is attributed to the efficient structure design and optimized spatial distribution of active sites, which enhance the electron transfer rate and decrease the reaction energy barrier. Mechanistic studies reveal that the synergetic effect between encapsulated nanoparticles and surface-modified Fe/N sites plays a crucial role in promoting efficient nitrate adsorption and selective ammonia production. These findings highlight the potential of strategically engineered CNF-based composites for nitrate reduction and other advanced electrocatalytic applications. © 2025

关键词： Carbon nanofibers

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Spatial continuity and stress transfer:Primary and complementary factors shaping pure-swarm laboratory catalog into mixed burst-like and swarm-like

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Journal of Rock Mechanics and geotechnical engineering 2025年第1期17卷 55-70页

作者： Qiquan Xiong Qing Lin Yue Gao Jesse C.Hampton Geomechanics and Damage Group(GeoD) Department of Civil and Environmental EngineeringUniversity of Wisconsin-MadisonUSA State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China College of Petroleum Engineering China University of PetroleumBeijing102249China

Natural earthquakes and micro-seismicity resulting from hydraulic fracturing or other engineering practices display distinctively different spatial-temporal features,like mixed burst-and swarm-like features or predominantly swarm-like *** mechanism(s)contributing to such observations can be *** present the inspections on the dynamic formation process of the single swarm-like tree in laboratory acoustic emission(AE)*** largest swarm-like trees can contain>97%AE events from the entire catalog within a test;and all catalogs under investigation display scale-invariance *** formation of the largest swarm-like tree correlates with the rock fracture process analogue of the source pervasive process,where its AE releases exhibit significant spatial *** to other laboratory catalogs under different laboratory settings helps us identify the spatial continuity of the rock fracture process as the primary factor in forming the largest swarm-like trees at laboratory *** stress transfer process is involved in the rock fracture process for the tests having pre-existing spatial *** perturbations on the spatial information induced by the stress transfer process further confirm that stress transfer also serves to shift the pure swarm-like catalog into a mixed burst-and swarm-like *** laboratory observations may provide inspirational insights for understanding the field-scale mechanism(s)shaping the spatial-temporal energy release features.

关键词： Rock fracture laboratory catalogs Swarm-like events Acoustic emission(AE) Scale-invariance

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Centrifuge modelling of dry granular run-out processes under deflective Coriolis condition

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Journal of Rock Mechanics and geotechnical engineering 2025年第2期17卷 1227-1239页

作者： Bei Zhang Yandong Bi Yu Huang College of Geological Engineering and Geomatics Chang’an UniversityXi’an710054China Key Laboratory of Western China's Mineral Resources and Geological Engineering Ministry of EducationChang'an UniversityXi'an710054China Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai200092China The State Key Laboratory on Disaster Reduction in Civil Engineering Tongji UniversityShanghai200092China

Coriolis effects,encompassing the dilative,compressive,and deflective manifestations,constitute pivotal considerations in the centrifugal modelling of high-speed granular run-out ***,under the deflective Coriolis condition,the velocity component parallel to the rotational axis exerts no influence on the magnitude of Coriolis *** circumstance implies a potential mitigation of the Coriolis force's deflective ***,extant investigations predominantly emphasize the dilative and compressive Coriolis effects,largely neglecting the pragmatic import of the deflective Coriolis *** pursuit of this gap,a series of discrete element method(DEM)simulations have been conducted to scrutinize the feasibility of centrifugal modelling for dry granular run-out processes under deflective Coriolis *** findings concerning the deflective Coriolis effect reveal a consistent rise in the run-out distance by 2%–16%,a modest increase in bulk flow velocity of under 4%,and a slight elevation in average flow depth by no more than 25%.These alterations display smaller dependence on the specific testing conditions due to the granular flow undergoing dual deflections in opposing *** underscores the significance and utility of the deflective Coriolis ***,the anticipated reduction in error in predicting the final run-out distance is substantial,potentially reaching a 150%improvement compared to predictions made under the dilative and compressive Coriolis ***,the deflective Coriolis condition is advised when the final run-out distance of the granular flow is the main *** mitigate the impact of Coriolis acceleration,a greater initial height of the granular column is recommended,with a height/width ratio exceeding 1,as the basal friction of the granular material plays a crucial role in mitigating the deflective Coriolis *** more transverse-uniform flow properties,the width of the granular

关键词： Centrifuge modelling Granular flow Run-out process Deflective coriolis condition Discrete element modelling

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