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Effects of the initiation position on the damage and fracture characteristics of linear-charge blasting in rock

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International Journal of Minerals,Metallurgy and Materials 2024年第3期31卷 443-451页

作者： Chenxi Ding Renshu Yang Xiao Guo Zhe Sui Chenglong Xiao liyun Yang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083China State Key Lab of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

To study the effects of the initiation position on the damage and fracture characteristics of linear-charge blasting, blasting model experiments were conducted in this study using computed tomography scanning and three-dimensional reconstruction methods. The fractal damage theory was used to quantify the crack distribution and damage degree of sandstone specimens after blasting. The results showed that regardless of an inverse or top initiation, due to compression deformation and sliding frictional resistance, the plugging medium of the borehole is effective. The energy of the explosive gas near the top of the borehole is consumed. This affects the effective crushing of rocks near the top of the borehole, where the extent of damage to Sections Ⅰ and Ⅱ is less than that of Sections Ⅲ and Ⅳ. In addition, the analysis revealed that under conditions of top initiation, the reflected tensile damage of the rock at the free face of the top of the borehole and the compression deformation of the plug and friction consume more blasting energy, resulting in lower blasting energy efficiency for top initiation. As a result, the overall damage degree of the specimens in the top-initiation group was significantly smaller than that in the inverse-initiation group. Under conditions of inverse initiation, the blasting energy efficiency is greater, causing the specimen to experience greater damage. Therefore, in the engineering practice of rock tunnel cut blasting, to utilize blasting energy effectively and enhance the effects of rock fragmentation, using the inverse-initiation method is recommended. In addition, in three-dimensional(3D) rock blasting, the bottom of the borehole has obvious end effects under the conditions of inverse initiation, and the crack distribution at the bottom of the borehole is trumpet-shaped. The occurrence of an end effect in the 3D linear-charge blasting model experiment is related to the initiation position and the blocking condition.

关键词： blasting linear charge initiation position computed tomography three-dimensional reconstruction damage

Effects of thawing-induced softening on fracture behaviors of frozen rock

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 979-989页

作者： Ting Wang Hailiang Jia Qiang Sun Xianjun Tan liyun Tang College of Geology and Environment Xi’an University of Science and TechnologyXi’an710054China College of Architecture and Civil Engineering Xi’an University of Science and TechnologyXi’an710054China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430064China

Due to the presence of ice and unfrozen water in pores of frozen rock,the rock fracture behaviors are susceptible to *** this study,the potential thawing-induced softening effects on the fracture behaviors of frozen rock is evaluated by testing the tension fracture toughness(KIC)of frozen rock at different temperatures(i.e.-20℃,-15℃,-12℃,-10℃,-8℃,-6℃,-4℃,-2℃,and 0℃).Acoustic emission(AE)and digital image correlation(DIC)methods are utilized to analyze the microcrack propagation during *** melting of pore ice is measured using nuclear magnetic resonance(NMR)*** results indicate that:(1)The KIC of frozen rock decreases moderately between-20℃ and-4℃,and rapidly between-4℃ and 0℃.(2)At-20℃ to-4℃,the fracturing process,deduced from the DIC results at the notch tip,exhibits three stages:elastic deformation,microcrack propagation and microcrack ***,at-4℃e0℃,only the latter two stages are observed.(3)At-4℃e0℃,the AE activities during fracturing are less than that at-20℃ to-4℃,while more small events are reported.(4)The NMR results demonstrate a reverse variation trend in pore ice content with increasing temperature,that is,a moderate decrease is followed by a sharp decrease and-4℃ is exactly the critical ***,we interpret the thawing-induced softening effect by linking the evolution in microscopic structure of frozen rock with its macroscopic fracture behaviors as follow:from-20℃ to-4℃,the thickening of the unfrozen water film diminishes the cementation strength between ice and rock skeleton,leading to the decrease in fracture ***-4℃ to 0℃,the cementation effect of ice almost vanishes,and the filling effect of pore ice is reduced significantly,which facilitates microcrack propagation and thus the easier fracture of frozen rocks.

关键词： Frozen sandstone Different thawing temperature Fracture toughness Microcrack propagation process Unfrozen water content

Recent advances in visible light-mediated chemical transformations of enaminones

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Chinese Chemical Letters 2024年第2期35卷 4-15页

作者： Yu Han liyun Zhou Chengyu Wang Shangti Feng Rong Ma Jie-Ping Wan College of Chemistry and Chemical Engineering Jiangxi Normal UniversityNanchang 330022China School of Chemistry and Chemical Engineering Linyi UniversityLinyi 276000China Linyi Sanfeng Chemical Co. Ltd.Linyi 276000China

Enaminones,which possesses both the nucleophilic enamine as well as electrophilic enone structures,are well known versatile building blocks in organic ***,visible light-mediated reactions have emerged as useful synthetic strategy with enhanced *** the last decade,various photochemical transformations of enaminones have been developed to construct cyclic or acyclic *** this review,we describe the recent advances in visible light-mediated chemical transformations of *** discussion on the reaction mechanism of the related reactions is given to provide guide to the ***,a summary on the existing challenges and the future outlook towards the development of practical photocatalytic reactions of enaminones is also presented.

关键词： Enaminone Visible light C-H functionalization C=C bond cleavage Cyclization Multicomponent reactions

Synthesis of carbon quantum dots decorating Bi_(2)MoO_(6) microspherical heterostructure and its efficient photocatalytic degradation of antibiotic norfloxacin

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Chinese Chemical Letters 2024年第8期35卷 373-378页

作者： Meijuan Chen liyun Zhao Xianjin Shi Wei Wang Yu Huang Lijuan Fu Lijun Ma School of Human Settlements and Civil Engineering Xi’an Jiaotong UniversityXi’an 710049China Key Lab of Aerosol Chemistry and Physics State Key Laboratory of Loess and Quaternary Geology(SKLLQG)Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China

In this study,three-dimensional microspherical CQDs/Bi_(2)MoO_(6)heterostructures were synthesized using a simple alcohol-thermal *** was found that the CQDs/Bi_(2)MoO_(6)had a large specific surface area of 56.0 m^(2)/g,and the introduction of CQDs extended the light absorption spectrum from 480 nm to 496 *** utilizing the synthesized CQDs/Bi_(2)MoO_(6)composite for photocatalytic degradation of antibiotic nor-floxacin in a water environment,complete decay of norfloxacin and effective removal of total organic car-bon(TOC)were achieved within 30 *** the optimization of material synthesis and experimen-tal conditions,the optimal CQDs loading amount was determined as 200μL,the optimal CQDs/Bi_(2)MoO_(6)dosage was 0.8 g/***,the CQDs/Bi_(2)MoO_(6)worked well under a wide pH range of *** co-existence of HCO_(3)−enhanced the norfloxacin decay,while the presence of Cl^(−),NO_(3)^(−),and SO_(4)^(2−)slightly retarded *** synthesized CQDs/Bi_(2)MoO_(6)had the great potential in removing and mineralizing nor-floxacin in real aquatic environments.

关键词： Bi_(2)MoO_(6) CQDs Heterojunction Norfloxacin Photocatalysis

A long-term daily gridded snow depth dataset for the Northern Hemisphere from 1980 to 2019 based on machine learning

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Big Earth Data 2024年第2期8卷 274-301页

作者： Yanxing Hu Tao Che liyun Dai Yu Zhu Lin Xiao Jie Deng Xin Li Key Laboratory of Remote Sensing of Gansu Province Heihe Remote Sensing Experimental Research StationNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouChina College of Resources and Environment University of Chinese Academy of SciencesBeijingChina State Key Laboratory of Tibetan Plateau Earth System Resources and Environment(TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijingChina Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security Institute of International Rivers and Eco-SecurityYunnan UniversityKunmingChina National Forestry and Grassland Administration Key Laboratory of Forest Resource Conservation and Ecological Safety on the Upper Reaches of the Yangtze River Sichuan Province Key Laboratory of Ecological Forestry Engineering on the Upper Reaches of the Yangtze RiverCollege of ForestrySichuan Agricultural UniversityChengduChina

A high-quality snow depth product is very import for cryospheric science and its related *** long time-series snow depth products covering the Northern Hemisphere can be divided into two categories:remote sensing snow depth products and reana-lysis snow depth ***,existing gridded snow depth products have some *** sensing-derived snow depth products are temporally and spatially discontinuous and tend to underestimate snow depth,while reanalysis snow depth products have coarse spatial resolutions and great *** overcome these problems,in our previous work we proposed a novel data fusion framework based on Random Forest Regression of snow products from Advanced Microwave Scanning Radiometer for the Earth Observing System(AMSR-E),Advanced Microwave Scanning Radiometer-2(AMSR2),Global Snow Monitoring for Climate Research(GlobSnow),the Northern Hemisphere Snow Depth(NHSD),ERA-Interim,and Modern-Era Retrospective Analysis for Research and Applications,ver-sion 2(MERRA-2),incorporating geolocation(latitude and longitude),and topographic data(elevation),which were used as input indepen-dent *** than 30,000 ground observation sites were used as the dependent variable to train and validate the model in different time *** fusion framework resulted in a long time series of continuous daily snow depth product over the Northern Hemisphere with a spatial resolution of 0.25°.Here,we compared the fused snow depth and the original gridded snow depth products with 13,272 observation sites,showing an improved precision of our *** evaluation indices of the fused(best original)dataset yielded a coeffi-cient of determination R2 of 0.81(0.23),Root Mean Squared Error(RMSE)of 7.69(15.86)cm,and Mean Absolute Error(MAE)of 2.74(6.14)*** of the bias(88.31%)between the fused snow depth and in situ observations was in the range of−5 cm to 5 *** accuracy assessment of independent snow observation sites-Sodank

关键词： Snow depth datasets machine learning data fusion Northern Hemisphere

Rice stem lodging properties and bending modeling under the influence of circadian temperature difference

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International Journal of Agricultural and Biological Engineering 2024年第3期17卷 21-32页

作者： Bangzhui Wang Zhong Tang liyun Lao Guoqiang Wang Tiantian Jing Yao Yu School of Agricultural Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina School of Water Energy and EnvironmentCranfield UniversityMK430ALUK Department of Agricultural Engineering Jiangsu Agriculture&Animal Husbandry Science and Technology Vocational CollegeTaizhou 225300JiangsuChina

Under diurnal temperature stress,the vascular bundle content of mature rice stems will change which will cause a change in the modulus of ***,the rice stems will collapse with the reduction in bending resistance because of the change in the modulus of *** order to reveal the distribution of vascular bundle gradients in rice stems under different climatic temperatures and explore the locations where stems are prone to bending and the form of stem damage,this study established a model of stem stiffness under free loading based on observing microstructure of the *** lodging characteristics of rice stems was explored seldom in different environmental temperatures from a micro structure of rice ***,the statistical analysis and t-tests were carried out on stems 1 to 4 in combination for cantilever bending tests at room temperature on stem internodes 3,versus three-point bending tests at-10℃ to 65℃ temperature *** showed that the bending resistance of the stem can be well predicted by using the vascular bundle distribution regression model and the variable stiffness mechanical *** bending resistance of No.3 stem was established by using the results obtained from the three-point bending test in a temperature range between 10℃-65℃.The correction coefficient TF of stem bending resistance under temperature difference induced stress was established based on the Gauss regression *** analysis showed that the bending resistance of No.3 stem was relatively large in a temperature range of 16℃-34℃.This study elucidated the variations of the mechanical properties of rice stems under temperature difference induced stress and provided a theoretical foundation for understanding the lodging characteristics of rice during mechanized harvesting.

关键词： rice stem vascular gradient stiffness model stem bending temperature stress

Effect of Blasting Stress Wave on Dynamic Crack Propagation

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工程与科学中的计算机建模(英文) 2024年第1期138卷 349-368页

作者： Huizhen Liu Duanying Wan Meng Wang Zheming Zhu liyun Yang Key Laboratory for Old Bridge Detection&Reinforcement Technology of the Ministry of Transportation Beijing100088China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing100083China MOE Key Laboratory of Deep Underground Science and Engineering School of Architecture and EnvironmentSichuan UniversityChengdu610065China

Stress waves affect the stress field at the crack tip and dominate the dynamic crack ***,evaluating the influence of blasting stress waves on the crack propagation behavior and the mechanical characteristics of crack propagation is of great significance for engineering *** this study,ANSYS/LS-DYNA was used for blasting numerical simulation,in which the propagation characteristics of blasting stress waves and stress field distribution at the crack tip were closely ***,ABAQUS was applied for simulating the crack propagation path and calculating dynamic stress intensity factors(DSIFs).The universal function was calculated by the *** results show that:the compressive wave causes the crack to close and the reflected tensile wave drives the crack to initiate and propagate,and failure mode is mainly tensile *** crack propagation velocity varies with time,which increases at first and then decreases,and the crack arrest occurs due to the attenuation of stress waves and dissipation of the blasting *** addition,crack arrest toughness is smaller than the crack initiation toughness,applied pressure waveforms(such as the peak pressure,duration,waveforms,wavelengths and loading rates)have a great influence on *** is conducive to our deep understanding or the study of blasting stress waves dominated fracture,suggesting a broad reference for the further development of rock blasting in engineering practice.

关键词： Crack propagation blasting stress wave dynamic stress intensity factor pressure waveform numerical simulation

Seismogenic Structure of the 1605 Qiongshan M7½ Earthquake and Its Holocene Activity History in Northern Hainan Island, China: Evidence from Cross-Section Drilling and Shallow Seismic Profile

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Journal of Earth Science 2024年第3期35卷 905-917页

作者： Chaoqun Wang liyun Jia Daogong Hu Shibiao Bai Zhengwang Hu Dongxia Sun Xiaoxiao Yang Lei Zhang Xiumin Ma Institute of Geomechanics Chinese Academy of Geological SciencesBeijing 100081China Key Laboratory of Active Tectonics and Geological Safety Ministry of Natural ResourcesBeijing 100081China Key Laboratory of Geohazard Prevention of Hilly Mountains Ministry of Land and Resources(Fujian Key Laboratory of Geohazard Prevention)Fuzhou 350002China Observation and Research Station of Crustal Stress and Strain in Beijing Ministry of Natural ResourcesBeijing 100081China College of Marine Science and Engineering Nanjing Normal UniversityNanjing 210023China Hubei Subsurface Multi-Scale Imaging Key Laboratory School of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China

The 1605 M7½ Earthquake is the only earthquake in the history of China that has caused large-scale land subsidence into the sea,with the total area of land subsidence exceeding 100 *** disaster has led to the sinking of 72 *** is still no clear understanding of the source seismogenic fault of this *** this work,we conducted a detailed study of the middle segment of the Maniao-Puqian fault(MPF),which is the epicenter area,through geomorphological survey,data collection,shallow seismic exploration,cross-section drilling,and chronological *** results showed that the middle segment of the MPF zone is composed of three nearly parallel normal faults with a dextral strike-slip:“Macun-Luodou fault(F2-1),Haixiu-Dongyuan fault(F2-2),and ChangliuZhuxihe fault(F2-3)”.And F2-2 is composed of two secondary faults,namely F2-2′and F2-2″,with a flower-shaped structure buried under the *** is distributed nearly east-west,dipping to the north and has experienced at least five stages of activities since the *** vertical activity rates of F2-2′and F2-2″are~2.32 and~2.5 mm/a,since the Holocene,*** were eight cycles of transgression and regression since the *** fault activity resulted in the thickening of the Holocene strata with a slight dip to the south,on the hanging wall,showing V-shaped *** MPF is likely the source seismogenic fault of the M7½ earthquake that hit Qiongshan in 1605.

关键词： seismogenic structure earthquakes Maniao-Puqian fault fault activity history geomorphology.

Woven fabric triboelectric nanogenerators for human-computer interaction and physical health monitoring

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Nano Research 2024年第6期17卷 5540-5548页

作者： Yu Miao Mengjuan Zhou Jia Yi Yanyan Wang Guangjin Tian Hongxia Zhang Wenlong Huang Wenhao Wang Ronghui Wu liyun Ma College of Textile and Clothing Xinjiang UniversityUrumqi 830046China College of Textiles Donghua UniversityShanghai 201620China College of Physics Xiamen UniversityXiamen 201620China Department of Bioengineering Imperial College LondonLondon SW72AZUK

Triboelectric nanogenerator(TENG)converts mechanical energy into valuable electrical energy,offering a solution for future energy *** an indispensable part of TENG,textile TENG(T-TENG)has incredible advantages in harvesting biomechanical energy and physiological signal ***,the application of T-TENG is restricted,partly because the fabric structure parameter and structure on T-TENG performance have not been fully *** study comprehensively investigates the effect of weaving structure on fabric TENGs(F-TENGs)for direct-weaving yarn TENGs and post-coating fabric *** direct-weaving F-TENGs,a single-yarn TENG(Y-TENG)with a core-sheath structure is fabricated using conductive yarn as the core layer yarn and polytetrafluoroethylene(PTFE)filaments as the sheath *** fabrics with five different sets of parameters were designed and *** post-coating F-TENGs,fabrics with weaving structures of plain,twill,satin,and reinforced twill were fabricated and coated with conductive silver ***,the twill F-TENGs have the best electrical outputs,followed by the satin F-TENGs and plain weave ***,the increase of the Y-TENG gap spacing was demonstrated to improve the electrical output ***,T-TENGs are demonstrated for human-computer interaction and self-powered real-time *** systematic work provides guidance for the future T-TENG’s design.

关键词： single-yarn triboelectric nanogenerators woven fabric triboelectric nanogenerators fabric weaving structures and parameters human-computer interaction physical health monitoring