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Mechanical responses of anchoring structure under triaxial cyclic loading 被引量:2
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作者 Peng Wang Nong Zhang +5 位作者 Qun Wei Xingliang Xu Guangzhen Cui Aoran Li Sen Yang Jiaguang Kan 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第2期545-560,共16页
Dynamic load on anchoring structures(AS)within deep roadways can result in cumulative damage and failure.This study develops an experimental device designed to test AS under triaxial loads.The device enables the inves... Dynamic load on anchoring structures(AS)within deep roadways can result in cumulative damage and failure.This study develops an experimental device designed to test AS under triaxial loads.The device enables the investigation of the mechanical response,failure mode,instability assessment criteria,and anchorage effect of AS subjected to combined cyclic dynamic-static triaxial stress paths.The results show that the peak bearing strength is positively correlated with the anchoring matrix strength,anchorage length,and edgewise compressive strength.The bearing capacity decreases significantly when the anchorage direction is severely inclined.The free face failure modes are typically transverse cracking,concave fracturing,V-shaped slipping and detachment,and spallation detachment.Besides,when the anchoring matrix strength and the anchorage length decrease while the edgewise compressive strength,loading rate,and anchorage inclination angle increase,the failure intensity rises.Instability is determined by a negative tangent modulus of the displacement-strength curve or the continued deformation increase against the general downward trend.Under cyclic loads,the driving force that breaks the rock mass along the normal vector and the rigidity of the AS are the two factors that determine roadway stability.Finally,a control measure for surrounding rock stability is proposed to reduce the internal driving force via a pressure relief method and improve the rigidity of the AS by full-length anchorage and grouting modification. 展开更多
关键词 Triaxial stress Dynamic-static combination load cyclic loading Anchoring structure(AS) Cumulative damage
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灯盏乙素通过环状GMP-AMP合酶-干扰素基因刺激因子通路抑制BV-2小胶质细胞介导的神经炎症
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作者 段兆达 杨力 +4 位作者 陈浩伦 刘腾腾 郑立扬 徐冬垚 吴春云 《解剖学报》 CAS CSCD 2024年第2期133-142,共10页
目的探讨灯盏乙素对脂多糖(LPS)诱导的BV-2小胶质细胞神经炎症的影响。方法培养BV-2小胶质细胞系,将BV-2小胶质细胞分为对照组(Ctrl)、环状GMP-AMP合酶(cGAS)抑制剂RU320521(RU.521)组、LPS组、LPS+RU.521组、LPS+灯盏乙素预处理(LPS+S... 目的探讨灯盏乙素对脂多糖(LPS)诱导的BV-2小胶质细胞神经炎症的影响。方法培养BV-2小胶质细胞系,将BV-2小胶质细胞分为对照组(Ctrl)、环状GMP-AMP合酶(cGAS)抑制剂RU320521(RU.521)组、LPS组、LPS+RU.521组、LPS+灯盏乙素预处理(LPS+S)组、LPS+S+RU.521组,共6组。Western blotting及免疫荧光双标染色法检测并观察BV-2小胶质细胞中cGAS、干扰素基因刺激因子(STING)、核因子κB(NF-κB)、磷酸化NF-κB(p-NF-κB)、PYD结构域蛋白3(NLRP3)和肿瘤坏死因子α(TNF-α)的表达变化(n=3)。结果Western blotting和免疫荧光双标染色均显示,与对照组相比,LPS诱导后,BV-2小胶质细胞中cGAS、STING、p-NF-κB、NLRP3和TNF-α蛋白的表达水平显著升高(P<0.05);与LPS组相比,LPS+S组中cGAS、STING、p-NF-κB、NLRP3和TNF-α蛋白的表达水平显著下降(P<0.05)。使用cGAS通路抑制剂RU.521后显示了与灯盏乙素预处理组相似的作用效果。此外,NF-κB在各组的变化不明显(P>0.05)。结论灯盏乙素干预抑制BV-2小胶质细胞介导的神经炎症反应,可能与cGAS-STING信号通路有关。 展开更多
关键词 灯盏乙素 BV-2小胶质细胞 环状gmp-amp合酶-干扰素基因刺激因子通路 PYD结构域蛋白3 神经炎症 免疫荧光 免疫印迹法
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Damage evolution of rock-encased-backfill structure under stepwise cyclic triaxial loading 被引量:1
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作者 Xin Yu Yuye Tan +4 位作者 Weidong Song John Kemeny Shengwen Qi Bowen Zheng Songfeng Guo 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第2期597-615,共19页
Rock-encased-backfill(RB)structures are common in underground mining,for example in the cut-andfill and stoping methods.To understand the effects of cyclic excavation and blasting activities on the damage of these RB ... Rock-encased-backfill(RB)structures are common in underground mining,for example in the cut-andfill and stoping methods.To understand the effects of cyclic excavation and blasting activities on the damage of these RB structures,a series of triaxial stepwise-increasing-amplitude cyclic loading experiments was conducted with cylindrical RB specimens(rock on outside,backfill on inside)with different volume fractions of rock(VF=0.48,0.61,0.73,and 0.84),confining pressures(0,6,9,and 12 MPa),and cyclic loading rates(200,300,400,and 500 N/s).The damage evolution and meso-crack formation during the cyclic tests were analyzed with results from stress-strain hysteresis loops,acoustic emission events,and post-failure X-ray 3D fracture morphology.The results showed significant differences between cyclic and monotonic loadings of RB specimens,particularly with regard to the generation of shear microcracks,the development of stress memory and strain hardening,and the contact forces and associated friction that develops along the rock-backfill interface.One important finding is that as a function of the number of cycles,the elastic strain increases linearly and the dissipated energy increases exponentially.Also,compared with monotonic loading,the cyclic strain hardening characteristics are more sensitive to rising confining pressures during the initial compaction stage.Another finding is that compared with monotonic loading,more shear microcracks are generated during every reloading stage,but these microcracks tend to be dispersed and lessen the likelihood of large shear fracture formation.The transition from elastic to plastic behavior varies depending on the parameters of each test(confinement,volume fraction,and cyclic rate),and an interesting finding was that the transformation to plastic behavior is significantly lower under the conditions of 0.73 rock volume fraction,400 N/s cyclic loading rate,and 9 MPa confinement.All the findings have important practical implications on the ability of backfill to support underground excavations. 展开更多
关键词 Rock and backfill Triaxial cyclic loading Volume fraction Damage evolution 3D visualization
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Liquefaction susceptibility and deformation characteristics of saturated coral sandy soils subjected to cyclic loadings-a critical review 被引量:1
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作者 Chen Guoxing Qin You +3 位作者 Ma Weijia Liang Ke Wu Qi C.Hsein Juang 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第1期261-296,共36页
Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions.Due to the unique marine depositional environment of coral sandy soils,the engineering characteristics and respons... Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions.Due to the unique marine depositional environment of coral sandy soils,the engineering characteristics and responses of these soils subjected to monotonic and cyclic loadings have been a subject of intense interest among the geotechnical and earthquake engineering communities.This paper critically reviews the progress of experimental investigations on the undrained behavior of coral sandy soils under monotonic and cyclic loadings over the last three decades.The focus of coverage includes the contractive-dilative behavior,the pattern of excess pore-water pressure(EPWP)generation and the liquefaction mechanism and liquefaction resistance,the small-strain shear modulus and strain-dependent shear modulus and damping,the cyclic softening feature,and the anisotropic characteristics of undrained responses of saturated coral sandy soils.In particular,the advances made in the past decades are reviewed from the following aspects:(1)the characterization of factors that impact the mechanism and patterns of EPWP build-up;(2)the identification of liquefaction triggering in terms of the apparent viscosity and the average flow coefficient;(3)the establishment of the invariable form of strain-based,stress-based,or energy-based EPWP ratio formulas and the unique relationship between the new proxy of liquefaction resistance and the number of cycles required to reach liquefaction;(4)the establishment of the invariable form of the predictive formulas of small strain modulus and strain-dependent shear modulus;and(5)the investigation on the effects of stress-induced anisotropy on liquefaction susceptibility and dynamic deformation characteristics.Insights gained through the critical review of these advances in the past decades offer a perspective for future research to further resolve the fundamental issues concerning the liquefaction mechanism and responses of coral sandy sites subjected to cyclic loadings associated with seismic events in marine environments. 展开更多
关键词 liquefaction susceptibility dynamic deformation characteristics coral sandy soil cyclic loading review and prospect
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Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions 被引量:1
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作者 Bin Wang Yujing Jiang +3 位作者 Qiangyong Zhang Hongbin Chen Richeng Liu Yuanchao Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3419-3436,共18页
To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)condit... To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)conditions.We analyzed the evolution of shear stress,normal stress,stress path,dilatancy characteristics,and friction coefficient and revealed the failure mechanisms of en-echelon joints at different angles.The results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle,with the shear strength at a positive angle exceeding that at a negative angle during shear cycles.As the number of cycles increases,the shear strength decreases rapidly,and the difference between the varying angles gradually decreases.Dilation occurs in the early shear cycles(1 and 2),while contraction is the main feature in later cycles(310).The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear cycles.The joint angle determines the asperities on the rupture surfaces and the block size,and thus determines the subsequent shear failure mode(block crushing and asperity degradation).At positive angles,block size is more greater and asperities on the rupture surface are smaller than at nonpositive angles.Therefore,the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles. 展开更多
关键词 En-echelon joint cyclic shear tests Shear stress Normal displacement Constant normal stiffness(CNS)
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Cyclic Beam Direction of Arrival Estimation Method for Ship Propeller Noise
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作者 ZHANG Xiaowei NIE Weihang +1 位作者 XU Ji YAN Yonghong 《Journal of Ocean University of China》 SCIE CAS CSCD 2024年第4期883-896,共14页
In underwater acoustic applications,the conventional cyclic direction of arrival algorithm faces challenges,including a low signal-to-noise ratio and high bandwidth when compared with modulated frequencies.In response... In underwater acoustic applications,the conventional cyclic direction of arrival algorithm faces challenges,including a low signal-to-noise ratio and high bandwidth when compared with modulated frequencies.In response to these issues,this paper introduces a novel,robust,and broadband cyclic beamforming algorithm.The proposed method substitutes the conventional cyclic covariance matrix with the variance of the cyclic covariance matrix as its primary feature.Assuming that the same frequency band shares a common steering vector,the new algorithm achieves superior detection performance for targets with specific modulation frequencies while suppressing interference signals and background noise.Experimental results demonstrate a significant enhancement in the directibity index by 81%and 181%when compared with the traditional Capon beamforming algorithm and the traditional extended wideband spectral cyclic MUSIC(EWSCM)algorithm,respectively.Moreover,the proposed algorithm substantially reduces computational complexity to 1/40th of that of the EWSCM algorithm,employing frequency band statistical averaging and covariance matrix variance. 展开更多
关键词 CYCLOSTATIONARITY direction of arrival extended wideband spectral cyclic music cyclic covariance matrix
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Enhancing capacitive deionization performance and cyclic stability of nitrogen-doped activated carbon by the electro-oxidation of anode materials
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作者 Xiaona Liu Baohua Zhao +6 位作者 Yanyun Hu Luyue Huang Jingxiang Ma Shuqiao Xu Zhonglin Xia Xiaoying Ma Shuangchen Ma 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第5期23-33,共11页
Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is cruci... Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N. 展开更多
关键词 Anodic oxidation Capacitive deionization cyclic stability N-DOPING
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Influence of cyclic ignition and steady-state operation on a 1–2 A barium tungsten hollow cathode
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作者 Fufeng WANG Tianhang MENG +1 位作者 Zhongxi NING Ximing ZHU 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第12期121-131,共11页
Booming low-power electric propulsion systems require 1–2 A hollow cathodes.Such cathodes are expected to go through more frequent ignitions in the low orbit,but the impact of cyclic ignitions on such 1–2 A barium t... Booming low-power electric propulsion systems require 1–2 A hollow cathodes.Such cathodes are expected to go through more frequent ignitions in the low orbit,but the impact of cyclic ignitions on such 1–2 A barium tungsten hollow cathodes with a heater was not clear.In this study,a 12,638-cyclic ignition test and a 6,000-hour-long life test on two identical cathodes were carried out.The discharge voltage of the cathode and the erosion of the orifice after cyclic ignition were all larger than that of the cathode after stable operation.This indicated that the impact of cycle ignition on the discharge performance of a low current BaO-W cathode with a heater was higher than that of stable operation.The results of the ion energy distribution function measured during the ignition period indicated that the main reason for the orifice expansion was ion bombardment.Therefore,it was necessary to pay attention to the number of ignitions for the lifetime of this kind of cathode. 展开更多
关键词 hollow cathode cyclic ignition stable operation ORIFICE ion bombardment
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Experimental study of the damage characteristics of rocks containing non-penetrating cracks under cyclic loading
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作者 Jun Xu Xiaochun Xiao +3 位作者 Lu Ma Sen Luo Jiaxu Jin Baijian Wu 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第2期197-210,共14页
The damage evolution process of non-penetrating cracks often causes some unexpected engineering disasters.Gypsum specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics ... The damage evolution process of non-penetrating cracks often causes some unexpected engineering disasters.Gypsum specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics under cyclic loading.The results show that under cyclic loading,the relationship between the number of non-penetrating crack(s)and the characteristic parameters(cyclic number,peak stress,peak strain,failure stress,and failure strain)of the pre-cracked specimens can be represented by a decreasing linear function.The damage evolution equation is fitted by calibrating the accumulative plastic strain for each cycle,and the damage constitutive equation is proposed by the concept of effective stress.Additionally,non-penetrating cracks are more likely to cause uneven stress distribution,damage accumulation,and local failure of specimen.The local failure can change the stress distribution and relieve the inhibition of non-penetrating crack extension and eventually cause a dramatic destruction of the specimen.Therefore,the evolution process caused by non-penetrating cracks can be regarded as one of the important reasons for inducing rockburst.These results are expected to improve the understanding of the process of spalling formation and rockburst and can be used to analyze the stability of rocks or rock structures. 展开更多
关键词 Damage characteristics Constitutive model Fissured rocks Non-penetrating crack cyclic loading
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Sodium Nitrate/Formamide Deep Eutectic Solvent as Flame-Retardant and Anticorrosive Electrolyte Enabling 2.6 V Safe Supercapacitors with Long Cyclic Stability
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作者 Huachao Yang Yiheng Qi +6 位作者 Zifan Wang Qinghu Pan Chuanzhi Zhang Jianhua Yan Kefa Cen Zheng Bo Kostya(Ken)Ostrikov 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第3期374-383,共10页
Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are ... Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are plagued by the limited operation voltage window(typically≤2.3 V)and inherent corrosion of current collectors.Herein,a novel deep eutectic solvent(DES)-based electrolyte which uses formamide(FMD)as hydrogen-bond donor and sodium nitrate(NaNO_(3))as hydrogen-bond acceptor is demonstrated.The electrolyte exhibits the wide electrochemical stability window(3.14 V),high electrical conductivity(14.01 mScm^(-1)),good flame-retardance,anticorrosive property,and ultralow cost(7%of the commercial electrolyte and 2%of WIS).Raman spectroscopy and Density Functional Theory calculations reveal that the hydrogen bonds between the FMD molecules and NO_(3)^(-)ions are primarily responsible for the superior stability and conductivity.The developed NaNO_(3)/FMD-based coin cell supercapacitor is among the best-performing state-of-art DES and WIS devices,evidenced by the high voltage window(2.6 V),outstanding energy and power densities(22.77 Wh kg^(-1)at 630 W kg^(-1)and 17.37 kW kg^(-1)at 12.55 Wh kg^(-1)),ultralong cyclic stability(86%after 30000 cycles),and negligible current collector corrosion.The NaNO_(3)/FMD industry adoption potential is demonstrated by fabricating 100 F pouch cell supercapacitors using commercial aluminum current collectors. 展开更多
关键词 cyclic stability deep eutectic solvents electrical conductivity electrochemical stability window SUPERCAPACITORS
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Remote plasma enhanced cyclic etching of a cyclosiloxane polymer thin film
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作者 Xianglin Wang Xinyu Luo +4 位作者 Weiwei Du Yuanhao Shen Xiaocheng Huang Zheng Yang Junjie Zhao 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第5期239-248,共10页
The continuous evolution of chip manufacturing demands the development of materials with ultra-low dielectric constants.With advantageous dielectric and mechanical properties,initiated chemical vapor deposited(iCVD)po... The continuous evolution of chip manufacturing demands the development of materials with ultra-low dielectric constants.With advantageous dielectric and mechanical properties,initiated chemical vapor deposited(iCVD)poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane)(pV3D3)emerges as a promising candidate.However,previous works have not explored etching for this cyclosiloxane polymer thin film,which is indispensable for potential applications to the back-end-of-line fabrication.Here,we developed an etching process utilizing O2/Ar remote plasma for cyclic removal of iCVD pV3D3 thin film at sub-nanometer scale.We employed in-situ quartz crystal microbalance to investigate the process parameters including the plasma power,plasma duration and O2 flow rate.X-ray photoelectron spectroscopy and cross-sectional microscopy reveal the formation of an oxidized skin layer during the etching process.This skin layer further substantiates an etching mechanism driven by surface oxidation and sputtering.Additionally,this oxidized skin layer leads to improved elastic modulus and hardness and acts as a barrier layer for protecting the bottom cyclosiloxane polymer from further oxidation. 展开更多
关键词 remote plasma cyclic etching cyclosiloxane polymer initiated chemical vapor deposition in-situ characterization
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Theoretical investigation on axial cyclic performance of monopile in sands using interface constitutive models
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作者 Pan Zhou Jingpei Li +2 位作者 Kaoshan Dai Stefan Vogt Seyedmohsen Miraei 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第7期2645-2662,共18页
Cyclic loads generated by environmental factors,such as winds,waves,and trains,will likely lead to performance degradation in pile foundations,resulting in issues like permanent displacement accumulation and bearing c... Cyclic loads generated by environmental factors,such as winds,waves,and trains,will likely lead to performance degradation in pile foundations,resulting in issues like permanent displacement accumulation and bearing capacity attenuation.This paper presents a semi-analytical solution for predicting the axial cyclic behavior of piles in sands.The solution relies on two enhanced nonlinear load-transfer models considering stress-strain hysteresis and cyclic degradation in the pile-soil interaction.Model parameters are calibrated through cyclic shear tests of the sand-steel interface and laboratory geotechnical testing of sands.A novel aspect involves the meticulous formulation of the shaft loadtransfer function using an interface constitutive model,which inherently inherits the interface model’s advantages,such as capturing hysteresis,hardening,degradation,and particle breakage.The semi-analytical solution is computed numerically using the matrix displacement method,and the calculated values are validated through model tests performed on non-displacement and displacement piles in sands.The results demonstrate that the predicted values show excellent agreement with the measured values for both the static and cyclic responses of piles in sands.The displacement pile response,including factors such as bearing capacity,mobilized shaft resistance,and convergence rate of permanent settlement,exhibit improvements compared to non-displacement piles attributed to the soil squeezing effect.This methodology presents an innovative analytical framework,allowing for integrating cyclic interface models into the theoretical investigation of pile responses. 展开更多
关键词 PILES cyclic degradation Load-transfer models Interface constitutive model Semi-analytical solution Model tests
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Dynamic failure process of expanded polystyrene particle lightweight soil under cyclic loading using discrete element method
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作者 Zhou Wei Hou Tianshun +3 位作者 Chen Ye Wang Qi Luo Yasheng Zhang Yafei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第4期815-828,共14页
Expanded polystyrene(EPS)particle-based lightweight soil,which is a type of lightweight filler,is mainly used in road engineering.The stability of subgrades under dynamic loading is attracting increased research atten... Expanded polystyrene(EPS)particle-based lightweight soil,which is a type of lightweight filler,is mainly used in road engineering.The stability of subgrades under dynamic loading is attracting increased research attention.The traditional method for studying the dynamic strength characteristics of soils is dynamic triaxial testing,and the discrete element simulation of lightweight soils under cyclic load has rarely been considered.To study the meso-mechanisms of the dynamic failure processes of EPS particle lightweight soils,a discrete element numerical model is established using the particle flow code(PFC)software.The contact force,displacement field,and velocity field of lightweight soil under different cumulative compressive strains are studied.The results show that the hysteresis curves of lightweight soil present characteristics of strain accumulation,which reflect the cyclic effects of the dynamic load.When the confining pressure increases,the contact force of the particles also increases.The confining pressure can restrain the motion of the particle system and increase the dynamic strength of the sample.When the confining pressure is held constant,an increase in compressive strain causes minimal change in the contact force between soil particles.However,the contact force between the EPS particles decreases,and their displacement direction points vertically toward the center of the sample.Under an increase in compressive strain,the velocity direction of the particle system changes from a random distribution and points vertically toward the center of the sample.When the compressive strain is 5%,the number of particles deflected in the particle velocity direction increases significantly,and the cumulative rate of deformation in the lightweight soil accelerates.Therefore,it is feasible to use 5%compressive strain as the dynamic strength standard for lightweight soil.Discrete element methods provide a new approach toward the dynamic performance evaluation of lightweight soil subgrades. 展开更多
关键词 lightweight soil cyclic loading dynamic triaxial test discrete element method hysteresis curve
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Strength and damage evolution mechanism of rock mass with holes under cyclic loading
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作者 LIU Hong-tao HAN Zi-jun +6 位作者 GUO Xiao-fei LIU Qin-yu QIAO Zhong-jin LIANG Jia-lu CHENG Wen-cong ZHANG Xi-ying ZHANG Yu-qi 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第8期2717-2735,共19页
The damage and failure law of rock mass with holes is of great significance to the stability control of roadways. This study investigates the mechanical properties and failure modes of porous rock masses under cyclic ... The damage and failure law of rock mass with holes is of great significance to the stability control of roadways. This study investigates the mechanical properties and failure modes of porous rock masses under cyclic loading, elucidates the acoustic emission (AE) characteristics and their spatial evolution, and establishes the interrelation among AE, stress, strain, time, and cumulative damage. The results reveal that the rock mass with holes and the intact rock mass show softening and hardening characteristics after cyclic loading. The plastic strain of the rock mass with holes is smaller than that of the intact rock mass, and the stress −strain curve shows hysteresis characteristics. Under uniaxial compression, the pore-bearing rock mass shows the characteristics of higher ringing count, AE energy, b-value peak, and more cumulative ringing count in the failure stage, while it shows lower characteristics under cyclic action. At the initial stage of loading, compared with the intact rock mass, the pore-containing rock mass shows the characteristics of a low b-value. The AE positioning and cumulative damage percentage are larger, and the AE positioning is denser around the hole. The specimen with holes is mainly shear failure, and the complete specimen is mainly tensile shear failure. 展开更多
关键词 roadway surrounding rock control acoustic emission cyclic loading failure mode precursor of destruction
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Effect of NaCl Concentration on the Cumulative Strain and Pore Distribution of Clay under Cyclic Loading
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作者 Xinshan Zhuang Shunlei Xia Ruijie Pan 《Fluid Dynamics & Materials Processing》 EI 2024年第2期447-461,共15页
Clay,as the most common soil used for foundationfill,is widely used in various infrastructure projects.The phy-sical and mechanical properties of clay are influenced by the pore solution environment.This study uses a GD... Clay,as the most common soil used for foundationfill,is widely used in various infrastructure projects.The phy-sical and mechanical properties of clay are influenced by the pore solution environment.This study uses a GDS static/dynamic triaxial apparatus and nuclear magnetic resonance experiments to investigate the effects of cyclic loading on clay foundations.Moreover,the development of cumulative strain in clay is analyzed,and afitting model for cumulative plastic strain is introduced by considering factors such as NaCl solution concentration,con-solidation stress ratio,and cycle number.In particular,the effects of the NaCl solution concentration and con-solidation stress ratio on the pore distribution of the test samples before and after cyclic loading are examined,and the relationship between microscopic pore size and macroscopic cumulative strain is obtained accordingly.Our results show that as the consolidation stress ratio grows,an increasing number of large pores in the soil samples are transformed into small pores.As the NaCl solution concentration becomes higher,the number of small pores gradually decreases,while the number of large pores remains unchanged.Cyclic loading causes the disappearance of the large pores in the samples,and the average pore size before cyclic loading is posi-tively correlated with the axial cumulative strain after cyclic loading.The cumulative strain produced by the soil under cyclic loading is inversely proportional to the NaCl solution concentration and consolidation stress ratio. 展开更多
关键词 Geotechnical engineering CLAY cyclic loading nuclear magnetic resonance NaCl solution consolidation ratio accumulative strain
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Numerical Analysis of Fiber Reinforced Polymer-Confined Concrete under Cyclic Compression Using Cohesive Zone Models
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作者 Mingxu Zhang Mingliang Wang Wei Zhang 《Structural Durability & Health Monitoring》 EI 2024年第5期599-622,共24页
This paper examines the mechanical behavior offiber reinforced polymer(FRP)-confined concrete under cyclic compression using the 3D cohesive zone model(CZM).A numerical modeling method was developed,employing zero-thick... This paper examines the mechanical behavior offiber reinforced polymer(FRP)-confined concrete under cyclic compression using the 3D cohesive zone model(CZM).A numerical modeling method was developed,employing zero-thickness cohesive elements to represent the stress-displacement relationship of concrete potential fracture surfaces and FRP-concrete interfaces.Additionally,mixed-mode damage plastic constitutive models were pro-posed for the concrete potential fracture surfaces and FRP-concrete interface,considering interfacial friction.Furthermore,an anisotropic plastic constitutive model was developed for the FRP composite jacket.The CZM model proposed in this study was validated using experimental data from plain concrete and large rupture strain(LRS)FRP-confined concrete subjected to cyclic compression.The simulation results demonstrate that the pro-posed model accurately predicts the mechanical response of both concrete and FRP-confined concrete under cyc-lic compression.Lastly,various parametric studies were conducted to investigate the internal failure mechanism of FRP-confined concrete under cyclic loading to analyze the influence of the inner friction plasticity of different components. 展开更多
关键词 cyclic compression CZM FRP wrapped concrete constitutive model fracture behavior
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Comprehensive interventions for adult cyclic vomiting syndrome complicated by superior mesenteric artery syndrome:A case report
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作者 Bo Liu Hui Sun +3 位作者 Yang Liu Min-Lan Yuan Hong-Ru Zhu Wei Zhang 《World Journal of Clinical Cases》 SCIE 2024年第29期6327-6334,共8页
BACKGROUND Cyclic vomiting syndrome(CVS)is a chronic functional gastrointestinal disorder involving the gut–brain interaction that is characterized by recurring episodes of nausea,vomiting,abdominal pain,and interspe... BACKGROUND Cyclic vomiting syndrome(CVS)is a chronic functional gastrointestinal disorder involving the gut–brain interaction that is characterized by recurring episodes of nausea,vomiting,abdominal pain,and interspersed complete normal periods.Superior mesenteric artery(SMA)syndrome(SMAS)is a vascular condition in which the horizontal portion of the duodenum is compressed due to a reduced angle between the aorta and the SMA.This condition presents with symptoms similar to CVS,posing challenges in distinguishing between the two and often resulting in misdiagnosis or inappropriate treatment.CASE SUMMARY A 20-year-old female patient presented with recurrent episodes of vomiting and experienced a persistent fear of vomiting for the past 2 years.She adopted conscious dietary restrictions,which led to severe malnutrition.Initially,she was diagnosed with SMAS,as revealed by computed tomography angiography.Despite efforts to increase the angle between the aorta and the SMA through weight gain,her vomiting did not improve.Finally,she was diagnosed with comorbidities including CVS,SMAS and anxiety disorder.She underwent comprehensive interventions,including enteral and parenteral nutritional supplementation,administration of antiemetic and anti-anxiety agents,and participation in mindfulness-based cognitive therapy.The patient eventually experienced a notable improvement in both body weight and clinical symptoms.CONCLUSION We present a rare case of CVS in an adult complicated with SMAS and propose additional treatment with nutritional support,pharmacological intervention,and psychotherapy. 展开更多
关键词 cyclic vomiting syndrome Superior mesenteric artery syndrome Anxiety disorder Nutritional supplementation Mindfulness-based cognitive therapy Case report
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The Effect of Preloading on the Cyclic Liquefaction Strength Measured in the Laboratory
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作者 Konstantinos Stamatopoulos 《Journal of Civil Engineering and Architecture》 2024年第6期269-275,共7页
The effect of preloading on the liquefaction cyclic strength was investigated by cyclic shear tests where horizontal shear stress oscillated about a zero mean value on sands with varying fines content and at varying p... The effect of preloading on the liquefaction cyclic strength was investigated by cyclic shear tests where horizontal shear stress oscillated about a zero mean value on sands with varying fines content and at varying prestress ratios, densities and verticalstresses. Test results showed a marked increase of the cyclic soil strength with the prestress ratio. The effect is more pronounced for the looser specimens. An empirical expression predicting this effect is proposed. This expression is validated from results of a field test. 展开更多
关键词 cyclic liquefaction shear stress field test
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The Performance of Small Diameter Aluminum Light Support Structures Containing Handholes under Cyclic Fatigue
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作者 Cameron R. Rusnak Aya Al-Hamami Craig C. Menzemer 《Open Journal of Civil Engineering》 2024年第2期196-213,共18页
Aluminum light poles play a pivotal role in modern infrastructure, ensuring proper illumination along highways and in populated areas during nighttime. These poles typically feature handholes near their bases, providi... Aluminum light poles play a pivotal role in modern infrastructure, ensuring proper illumination along highways and in populated areas during nighttime. These poles typically feature handholes near their bases, providing access to electrical wiring for installation and maintenance. While essential for functionality, these handholes introduce a vulnerability to the overall structure, making them a potential failure point. Although prior research and analyses on aluminum light poles have been conducted, the behavior of smaller diameter poles containing handholes remains unexplored. Recognizing this need, a research team at the University of Akron undertook a comprehensive experimental program involving aluminum light poles with handholes containing welded inserts in order to gain a better understanding of their fatigue life, mechanical behavior, and failure mechanisms. The research involved testing seven large-scale aluminum light poles each 8-inch diameter, with two separate handholes. These handholes included a reinforcement that was welded to the poles. Finite Element Analysis (FEA), statistical analysis, and comparison analysis with their large counterparts (10-inch diameter) were used to augment the experimental results. The results revealed two distinct failure modes: progressive crack propagation leading to ultimate failure, and rupture of the pole near the weld initiation/termination site around the handhole. The comparison analysis indicated that the 8-inch diameter specimens exhibited an average fatigue life exceeding that of their 10-inch counterparts by an average of 30.7%. The experimental results were plotted alongside the fatigue detail classifications outlined in the Aluminum Design Manual (ADM), enhancing understanding of the fatigue detail category of the respective poles/handholes. 展开更多
关键词 Light Pole Handhole cyclic Fatigue Fatigue Analysis Finite Element Analysis Statistical Analysis
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Investigation of the Micro-Mechanics of an Extruded Precipitation-Strengthened Magnesium Alloy under Cyclic Loading
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作者 Chuhao Liu Xiaodan Zhang +1 位作者 Huamiao Wang Yinghong Peng 《Journal of Materials Science and Chemical Engineering》 2024年第7期40-52,共13页
Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macrosc... Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macroscopic mechanical response of magnesium alloys under cyclic loading conditions, we employed a crystal plasticity model to analyze the stress-strain curves, specific crystal plane diffraction intensities, and the temporal evolution of various microscopic deformation mechanisms and twinning volume fractions for an extruded magnesium alloy, AXM10304, containing coherent precipitates. The research findings indicate that precipitation does not fundamentally alter the microscopic mechanisms of this alloy. However, it hinders twinning during the compression stage, mildly promotes detwinning during the tension stage, and enhances tension secondary hardening by elevating the difficulty of activation of the prismatic slip. 展开更多
关键词 cyclic Deformation Magnesium Alloy In-Situ Neutron Diffraction Precipitation Strengthening Crystal Plasticity Lattice Strain Mechanism Evolution
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