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Elastoplastic behavior of frozen sand-concrete interfaces under cyclic shear loading 被引量:1
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作者 Jian CHANG Jian-kun LIU +2 位作者 Ya-li LI Qi WANG Zhong-hua HAO 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2022年第9期683-703,共21页
The resilient modulus,accumulated plastic strain,peak shear stress,and critical shear stress are the elastoplastic behaviors of frozen sand–concrete interfaces under cyclic shear loading.They reflect the bearing capa... The resilient modulus,accumulated plastic strain,peak shear stress,and critical shear stress are the elastoplastic behaviors of frozen sand–concrete interfaces under cyclic shear loading.They reflect the bearing capacity of buildings(e.g.highspeed railways)in both seasonal frozen and permafrost regions.This study describes a series of direct shear experiments conducted on frozen sand–concrete interfaces.The results indicated that the elastoplastic behaviors of frozen sand–concrete interfaces,including the resilient modulus,accumulated plastic strain,and shear strength,are influenced by the boundary conditions(constant normal loading and constant normal height),initial normal stress,negative temperature,and cyclic-loading amplitude.The resilient modulus was significantly correlated with the initial normal stress and negative temperature,but not with the cyclic-loading amplitude and loading cycles.The accumulated plastic shear strain increased when the initial normal stress and cyclic-loading amplitude increased and the temperature decreased.Moreover,the accumulated plastic shear strain increment decreased when the loading cycles increased.The accumulated direction also varied with changes in the initial normal stress,negative temperature,and cyclic-loading amplitude.The peak shear stress of the frozen sand–concrete interface was affected by the initial normal stress,negative temperature,cyclic-loading amplitude,and boundary conditions.Nevertheless,a correlation was observed between the critical shear stress and the initial normal stress and boundary conditions.The peak shear stress was higher,and the critical shear stress was lower under the constant normal height boundary condition.Based on the results,it appears that the properties of frozen sand–concrete interfaces,including plastic deformation properties and stress strength properties,are influenced by cyclic shear stress.These results provide valuable information for the investigation of constitutive models of frozen soil–structure interfaces. 展开更多
关键词 frozen sand-concrete interface Cyclic direct shear test Elastoplastic behavior Direction of accumulated plastic strain Boundary condition
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Effects of thawing-induced softening on fracture behaviors of frozen rock 被引量:1
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作者 Ting Wang Hailiang Jia +2 位作者 Qiang Sun Xianjun Tan Liyun Tang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第3期979-989,共11页
Due to the presence of ice and unfrozen water in pores of frozen rock,the rock fracture behaviors are susceptible to temperature.In this study,the potential thawing-induced softening effects on the fracture behaviors ... Due to the presence of ice and unfrozen water in pores of frozen rock,the rock fracture behaviors are susceptible to temperature.In 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 fracturing.The melting of pore ice is measured using nuclear magnetic resonance(NMR)method.The 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 coalescence.However,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 temperature.Next,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 parameters.From-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. 展开更多
关键词 frozen sandstone Different thawing temperature Fracture toughness Microcrack propagation process Unfrozen water content
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A dynamic soil freezing characteristic curve model for frozen soil 被引量:1
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作者 Xiaokang Li Xu Li Jiankun Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3339-3352,共14页
The soil freezing characteristic curve(SFCC)plays a fundamental role in comprehending thermohydraulic behavior and numerical simulation of frozen soil.This study proposes a dynamic model to uniformly express SFCCs ami... The soil freezing characteristic curve(SFCC)plays a fundamental role in comprehending thermohydraulic behavior and numerical simulation of frozen soil.This study proposes a dynamic model to uniformly express SFCCs amidst varying total water contents throughout the freezing-thawing process.Firstly,a general model is proposed,wherein the unfrozen water content at arbitrary temperature is determined as the lesser of the current total water content and the reference value derived from saturated SFCC.The dynamic performance of this model is verified through test data.Subsequently,in accordance with electric double layer(EDL)theory,the theoretical residual and minimum temperatures in SFCC are calculated to be-14.5℃to-20℃for clay particles and-260℃,respectively.To ensure that the SFCC curve ends at minimum temperature,a correction function is introduced into the general model.Furthermore,a simplified dynamic model is proposed and investigated,necessitating only three parameters inherited from the general model.Additionally,both general and simplified models are evaluated based on a test database and proven to fit the test data exactly across the entire temperature range.Typical recommended parameter values for various types of soils are summarized.Overall,this study provides not only a theoretical basis for most empirical equations but also proposes a new and more general equation to describe the SFCC. 展开更多
关键词 frozen soils Unsaturated soils Soil freezing characteristic curve(SFCC) Mathematic models
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Frozen sand-concrete interface direct shear behavior under constant normal load and constant normal height boundary 被引量:1
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作者 Jian CHANG Jian-kun LIU Ya-li LI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2022年第11期917-932,共16页
The shear strength properties of the frozen sand–structure interface are critical for evaluating the serviceability of pile foundations in frozen ground.The shear characteristics of the frozen sand–concrete interfac... The shear strength properties of the frozen sand–structure interface are critical for evaluating the serviceability of pile foundations in frozen ground.The shear characteristics of the frozen sand–concrete interface were studied with two boundary conditions(constant normal load(CNL)and constant normal height(CNH)),at three normal stresses(100,200,and 300 k Pa),and at three temperatures(-2,-5,and-8℃).A detailed comparative analysis was performed to explore the principal factors affecting the shear/normal-shear displacement.The results showed that the shear behavior of the frozen sand–concrete interface under CNL was similar to that under CNH.The shear stress–shear displacement exhibited strain softening.The temperature and normal stress were the major influences on normal properties.The lower the temperature and the higher the normal stress,the greater was the elastic shear modulus.The peak shear stress and critical shear stress exhibited a dependence on normal stress.An exponential growth in the peak shear stress was observed as the temperature decreased.Critical shear stress was dependent on temperature.The value and percentage of peak ice-cementation in peak shear stress was affected by temperature and normal stress. 展开更多
关键词 frozen sand–concrete interface Peak shear strength Critical shear strength Ice-cementation Boundary condition
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Experimental and numerical interpretation on composite foundation consisting of soil-cement column within warm and ice-rich frozen soil
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作者 WANG Honglei ZHANG Jianming +2 位作者 WEI Shoucai SUN Zhizhong ZHANG Hu 《Journal of Mountain Science》 SCIE CSCD 2024年第1期313-321,共9页
Affected by climate warming and anthropogenic disturbances, the thermo-mechanical stability of warm and ice-rich frozen ground along the Qinghai-Tibet engineering corridor(QTEC) is continuously decreased, which may de... Affected by climate warming and anthropogenic disturbances, the thermo-mechanical stability of warm and ice-rich frozen ground along the Qinghai-Tibet engineering corridor(QTEC) is continuously decreased, which may delay the construction of major projects in the future. In this study, based on chemical stabilization of warm and icerich frozen ground, the soil-cement column(SCC) for ground improvement was recommended to reinforce the foundations in warm and ice-rich permafrost regions. To explore the validity of countermeasures mentioned above, both the original foundation and the composite foundation consisting of SCC with soil temperature of -1.0℃ were prepared in the laboratory, and then the plate loading tests were carried out. The laboratory investigations indicated that the bearing capacity of composite foundation consisting of SCC was higher than that of original foundation, and the total deformation of original foundation was greater than that of composite foundation, meaning that overall stability of foundation with warm and ice-rich frozen soil can be improved by SCC installation. Meanwhile, a numerical model considering the interface interaction between frozen soil and SCC was established for interpretating the bearing mechanism of composite foundation. The numerical investigations revealed that the SCC within composite foundation was responsible for the more applied load, and the applied load can be delivered to deeper zone in depth due to the SCC installation, which was favorable for improving the bearing characteristic of composite foundation. The investigations provide the valuable guideline for the choice of engineering supporting techniques to major projects within the QTEC. 展开更多
关键词 Chemical stabilization Ground improvement Composite foundation frozen soil engineering Qinghai-Tibet engineering corridor
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Experiment and constitutive modelling of creep deformation in the frozen silt-concrete interface
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作者 HE Fei LIU Qingquan +4 位作者 LEI Wanyu WANG Xu MAO Erqing LI Sheng CHEN Hangjie 《Journal of Mountain Science》 SCIE CSCD 2024年第9期3172-3185,共14页
To ensure the long-term safety and stability of bridge pile foundations in permafrost regions,it is necessary to investigate the rheological effects on the pile tip and pile side bearing capacities.The creep character... To ensure the long-term safety and stability of bridge pile foundations in permafrost regions,it is necessary to investigate the rheological effects on the pile tip and pile side bearing capacities.The creep characteristics of the pile-frozen soil interface are critical for determining the long-term stability of permafrost pile foundations.This study utilized a self-developed large stress-controlled shear apparatus to investigate the shear creep characteristics of the frozen silt-concrete interface,and examined the influence of freezing temperatures(−1,−2,and−5°C),contact surface roughness(0,0.60,0.75,and 1.15 mm),normal stress(50,100,and 150 kPa),and shear stress on the creep characteristics of the contact surface.By incorporating the contact surface’s creep behavior and development trends,we established a creep constitutive model for the frozen silt-concrete interface based on the Nishihara model,introducing nonlinear elements and a damage factor.The results revealed significant creep effects on the frozen silt-concrete interface under constant load,with creep displacement at approximately 2-15 times the instantaneous displacement and a failure creep displacement ranging from 6 to 8 mm.Under different experimental conditions,the creep characteristics of the frozen silt-concrete interface varied.A larger roughness,lower freezing temperatures,and higher normal stresses resulted in a longer sample attenuation creep time,a lower steady-state creep rate,higher long-term creep strength,and stronger creep stability.Building upon the Nishihara model,we considered the influence of shear stress and time on the viscoelastic viscosity coefficient and introduced a damage factor to the viscoplasticity.The improved model effectively described the entire creep process of the frozen silt-concrete interface.The results provide theoretical support for the interaction between pile and soil in permafrost regions. 展开更多
关键词 Creep characteristics Contact surface frozen silt Constitutive model Freezing temperature
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Mechanical behaviors of warm and ice-rich frozen soil stabilized with sulphoaluminate cement
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作者 WANG Honglei ZHANG Hu +2 位作者 ZHANG Jianming ZHANG Qi YIN Zhenhua 《Journal of Mountain Science》 SCIE CSCD 2024年第1期335-345,共11页
The warm and ice-rich frozen soil is characterized by high unfrozen water content, low shear strength and large compressibility, which is unreliable to meet the stability requirements of engineering infrastructures an... The warm and ice-rich frozen soil is characterized by high unfrozen water content, low shear strength and large compressibility, which is unreliable to meet the stability requirements of engineering infrastructures and foundations in permafrost regions. In this study, a novel approach for stabilizing the warm and ice-rich frozen soil with sulphoaluminate cement was proposed based on chemical stabilization. The mechanical behaviors of the stabilized soil, such as strength and stress-strain relationship, were investigated through a series of triaxial compression tests conducted at -1.0℃, and the mechanism of strength variations of the stabilized soil was also explained based on scanning electron microscope test. The investigations indicated that the strength of stabilized soil to resist failure has been improved, and the linear Mohr-Coulomb criteria can accurately reflect the shear strength of stabilized soil under various applied confining pressure. The increase in both curing age and cement mixing ratio were favorable to the growth of cohesion and internal friction angle. More importantly, the strength improvement mechanism of the stabilized soil is attributed to the formation of structural skeleton and the generation of cementitious hydration products within itself. Therefore, the investigations conducted in this study provide valuable references for chemical stabilization of warm and ice-rich frozen ground, thereby providing a basis for in-situ ground improvement for reinforcing warm and ice-rich permafrost foundations by soil-cement column installation. 展开更多
关键词 Permafrost regions frozen soil Mechanical behavior Chemical stabilization Ground improvement Ground modification
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Statistical modelling for effect of mix-parameters on properties of high-flowing sand-concrete 被引量:7
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作者 T.BOUZIANI A.BENMOUNAH M.BDRINA 《Journal of Central South University》 SCIE EI CAS 2012年第10期2966-2975,共10页
The high-flowing sand-concrete (HFSC) containing natural sands as aggregate was carried out. The high fluidity and stability of HFSC can be achieved by tailoring the mix design parameters, such as fine to coarse san... The high-flowing sand-concrete (HFSC) containing natural sands as aggregate was carried out. The high fluidity and stability of HFSC can be achieved by tailoring the mix design parameters, such as fine to coarse sand ratio, dosage of additions, water to binder ratio and dosage of admixtures. Mini-cone slump test, v-fl.mnel time test and viscosity model parameters were used to characterize the behaviour of HFSC in fresh state. The mechanical compressive strength in 28 d was also determined. A factorial design approach was used to establish models highlighting the effect of each mix-parameter on measured properties of HFSC. The derived models are valid for mixtures made with 0 to 0.3 of dune sand to total sand ratio, 82 to 418 kg/m3 of marble powder, 0.42 to 0.46 of water/binder ratio and 1.3% to 1.9% of superplasticizer high water-reducer. The results show that the derived models constitute very efficient means for understanding the influence of key mix-parameters on HFSC properties and are useful in selecting the optimum mix proportions, by simulating their impact on fluidity, stability and compressive strength. 展开更多
关键词 high-flowing sand-concrete factorial design FLUIDITY VISCOSITY mix-design parameters
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Dynamic mechanical characteristics of frozen subgrade soil subjected to freeze-thaw cycles 被引量:2
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作者 WANG Dan LIU En-long +3 位作者 YANG Cheng-song LIU You-qian ZHU Sheng-xian YU Qi-hao 《Journal of Mountain Science》 SCIE CSCD 2023年第1期242-255,共14页
As a widely-applied engineering material in cold regions, the frozen subgrade soils are usually subjected to seismic loading, which are also dramatically influenced by the freeze-thaw(F-T)cycles due to the varying tem... As a widely-applied engineering material in cold regions, the frozen subgrade soils are usually subjected to seismic loading, which are also dramatically influenced by the freeze-thaw(F-T)cycles due to the varying temperature. A series of dynamic cyclic triaxial experiments were conducted through a cryogenic triaxial apparatus for exploring the influences of F-T cycles on the dynamic mechanical properties of frozen subgrade clay.According to the experimental results of frozen clay at the temperature of-10℃, the dynamic responses and microstructure variation at different times of F-T cycles(0, 1, 5, and 20 cycles) were explored in detail.It is experimentally demonstrated that the dynamic stress-strain curves and dynamic volumetric strain curves of frozen clay are significantly sparse after 20F-T cycles. Meanwhile, the cyclic number at failure(Nf) of the frozen specimen reduces by 89% after 20freeze-thaw cycles at a low ratio of the dynamic stress amplitude. In addition, with the increasing F-T cycles,the axial accumulative strain, residual deformation,and the value of damage variable of frozen clay increase, while the dynamic resilient modulus and dynamic strength decrease. Finally, the influence of the F-T cycles on the failure mechanisms of frozen clay was discussed in terms of the microstructure variation. These studies contribute to a better understanding of the fundamental changes in the dynamic mechanical of frozen soils exposed to F-T cycles in cold and seismic regions. 展开更多
关键词 Freeze-thaw cycles frozen clay Dynamic triaxial test Dynamic mechanical properties
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A rate-dependent constitutive model for saturated frozen soil considering local breakage mechanism 被引量:1
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作者 Pan Wang Enlong Liu +1 位作者 Bin Zhi Bingtang Song 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第9期2458-2474,共17页
A rate-dependent constitutive model for saturated frozen soil is vital in frozen soil mechanics,especially when simultaneously describing the nonlinearity,dilatancy and strain-softening characteristics.The distributio... A rate-dependent constitutive model for saturated frozen soil is vital in frozen soil mechanics,especially when simultaneously describing the nonlinearity,dilatancy and strain-softening characteristics.The distribution of the non-uniform strain rate of saturated frozen soil at the meso-scale due to the local icecementation breakage is described by a newly binary-medium-based homogenization equation.Based on the field-equation-based approach of the meso-mechanics theory,the interaction expression of the strain rate at macro-and meso-scale is derived,which can give the strain rate concentration tensor at different crushed degrees.With the thermodynamics and empirical assumption,a breakage ratio in the rate-dependent form is determined.This overcomes the limitations of the existing binary-medium-based models that are difficult to simulate rate-dependent mechanical response.Based on these assumptions,a newly binary-medium-based rate-dependent model is proposed considering both the ice bond breakage and material composition characteristics of saturated frozen soil.The proposed constitutive model has been validated by the test results on frozen soils with different temperatures and strain rates. 展开更多
关键词 Binary-medium-based model Rate-dependency frozen soil Grain debonding effect Multi-scale constitutive model
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Effect of a filter cake on shear behavior of sand-concrete pile interface
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作者 CHEN Chen LENG Wu-ming +3 位作者 YANG Qi DONG Jun-li XU Fang RUAN Bo 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第6期2019-2032,共14页
A filter cake is often formed between soil and concrete during casting concrete in the ground,such as constructions of diaphragm walls and bored piles.The present study aims to investigate the effect of the filter cak... A filter cake is often formed between soil and concrete during casting concrete in the ground,such as constructions of diaphragm walls and bored piles.The present study aims to investigate the effect of the filter cake on the shear behavior of the sand-concrete pile interface.A series of sand-concrete interface direct shear tests were performed with a large-direct shear apparatus while considering different roughness(I=0,10,20 and 30 mm)and filter cake thickness(Δh=0,5 and 10 mm).For a smooth interface without a filter cake,the shear stress-horizontal displacement curves showed a“softening”response.The peak shear strength and friction angle decreased exponentially with increasing theΔh.Whereas,for a rough interface withΔh=5 or 10 mm,the shear stress-horizontal displacement curves presented a“hardening”response.The peak strength,as well as friction angle,decreased linearly with increasing theΔh.Moreover,a critical roughness I_(cr)of 10 mm was observed in the tests without a filter cake.The interface shear strength initially increased with increasing I but gradually decreased when the I exceeded I_(cr).In addition,the filter cake could reduce the roughness sensitivity on shear strength. 展开更多
关键词 filter cake sand-concrete pile interface large scale direct shear test shear behavior critical roughness
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Stabilized effects of L-S cement-mixed batter pile composite foundation for existed warm frozen soil subgrade
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作者 SUN Gao-chen YAO Gang +4 位作者 ZHANG Jian-ming LI Bo LI Jun-qi LIAN Wei-ping WEI Yi 《Journal of Mountain Science》 SCIE CSCD 2023年第2期542-556,共15页
In permafrost regions with warm frozen soil,subgrade thaw-collapse phenomenon commonly occurs,facing thaw collapse problems of the existed frozen soil subgrade,thus it is difficult to use traditional methods such as a... In permafrost regions with warm frozen soil,subgrade thaw-collapse phenomenon commonly occurs,facing thaw collapse problems of the existed frozen soil subgrade,thus it is difficult to use traditional methods such as active cooling and passive protection technology to stabilize the existed warm frozen soil subgrade.This study derives a novel stabilizer method,a long-short(L-S)cement-mixed batter pile composite foundation to stabilize the existed warm frozen soil subgrade.To solve the thawcollapse problems in warm frozen soil subgrade,high water content and large compressibility characteristics were compared between soft soil and warm frozen soils.Theoretical analysis of heat conduction and numerical simulation of finite element model were used to study the freeze–thaw process and evaluate the stabilized effects of the L-S cement-mixed batter piles on the warm frozen soil foundation of the Qinghai-Tibet Highway.Furthermore,the thaw process and mechanical properties of foundation and piles were analyzed by introducing the hydration heat factor in the thermodynamic control equation.The results indicate that the thawing displacement of the existed warm frozen soil subgrade was reduced owing to the“support”and“grasp”effects of the L-S cement-mixed batter piles on the surrounding soil.The composite ground formed by strengthening the warm frozen ground with batter piles could considerably improve the bearing capacity of the existed warm frozen ground,effectively restrain the deformation of the upper embankment,and improve the strength of the ground.The analysis can provide method for the construction design of cement mixing batter pile foundation in cold regions. 展开更多
关键词 Warm frozen soil subgrade Thaw collapse Thermal disturbance Long-short cementmixed batter pile Existed frozen soil subgrade
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Atypical progress of frozen shoulder after COVID-19 vaccination:A case report
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作者 Hyun-Seok Jo Hyeong-Min Kim +1 位作者 Jae-Young Han Hyeng-Kyu Park 《World Journal of Clinical Cases》 SCIE 2023年第15期3637-3642,共6页
BACKGROUND After vaccination was mandated worldwide,various adverse effects associated with the coronavirus disease 2019(COVID-19)vaccination,including shoulder pain,have been reported.Here,we report a case of new-ons... BACKGROUND After vaccination was mandated worldwide,various adverse effects associated with the coronavirus disease 2019(COVID-19)vaccination,including shoulder pain,have been reported.Here,we report a case of new-onset shoulder pain after BNT162b2(Comirnaty,Pfizer-BioNTech)mRNA vaccination.CASE SUMMARY A 50-year-old man visited our rehabilitation center with left shoulder range of motion(ROM)limitation that had persisted for more than 5 mo.The history included no specific noteworthy events,except vaccination.The pain in the patient’s left deltoid muscle appeared 1 day after the second BNT162b2 vaccination and intensified to severe pain.The patient self-administered aspirin,with which the pain subsided immediately,whereas ROM limitation persisted.At the first visit,the patient complained of dull pain and ROM restriction of the left shoulder(flexion 130°,abduction 110°,and external rotation 40°).Among the diagnostic studies conducted for the evaluation of the shoulder,magnetic resonance imaging showed a thickened coracohumeral ligament.Nerve conduction studies and needle electromyography showed no electrodiagnostic abnormalities.The patient received comprehensive rehabilitation for 7 mo and had an overall improvement in pain and ROM of the left shoulder.CONCLUSION In this case of severe shoulder pain after COVID-19 vaccination that subsided immediately with aspirin treatment,the exact cause and mechanism of pain are unclear.However,the clinical symptoms and diagnostic workups in our report suggest the possibility that the COVID-19 vaccination triggered an immunochemical response that resulted in shoulder pathology. 展开更多
关键词 COVID-19 VACCINATION Adhesive capsulitis frozen shoulder MECHANISM Case report
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On-Site Assessment of a Cryogenic Disinfectant for the Alpine Environment and Outer Packaging of Frozen Items
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作者 SHEN Jin YANG Bin +13 位作者 XIAO Jia Qing LI Lu Yao SUN Hui Hui DUAN Hong Yang ZHANG Wei LIANG Chen CHEN Lu LI Li CHEN Yan Yan LYU Yuan TANG Song WANG Jiao ZHANG Liu Bo WANG Lin 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2023年第2期174-184,共11页
Objective To study the effectiveness and feasibility of cryogenic disinfectants in different cold scenarios and analyze the key points of on-site cryogenic disinfection.Methods Qingdao and Suifenhe were selected as ap... Objective To study the effectiveness and feasibility of cryogenic disinfectants in different cold scenarios and analyze the key points of on-site cryogenic disinfection.Methods Qingdao and Suifenhe were selected as application sites for the manual or mechanical spraying of cryogenic disinfectants.The same amount of disinfectant(3,000 mg/L)was applied on cold chain food packaging,cold chain containers,transport vehicles,alpine environments,and article surfaces.The killing log value of the cryogenic disinfectant against the indicator microorganisms(Staphylococcus aureus and Escherichia coli)was used to evaluate the on-site disinfection effect.Results When using 3,000 mg/L with an action time of 10 min on the ground in alpine regions,the surface of frozen items,cold-chain containers,and cold chain food packaging in supermarkets,all external surfaces were successfully disinfected,with a pass rate of 100%.The disinfection pass rates for cold chain food packaging and cold chain transport vehicles of centralized supervised warehouses and food processing enterprises were 12.5%(15/120),81.67%(49/60),and 93.33%(14/15),respectively;yet,the surfaces were not fully sprayed.Conclusion Cryogenic disinfectants are effective in disinfecting alpine environments and the outer packaging of frozen items.The application of cryogenic disinfectants should be regulated to ensure that they cover all surfaces of the disinfected object,thus ensuring effective cryogenic disinfection. 展开更多
关键词 Cryogenic disinfectant COVID-19 An alpine environment DISINFECTION Outer packaging of frozen items
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Effects of confining pressure and temperature on strength and deformation behavior of frozen saline silty clay
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作者 Gang Wu GuoYu Li +4 位作者 Hui Bing Dun Chen YaPeng Cao LiYun Tang HaiLiang Jia 《Research in Cold and Arid Regions》 CSCD 2023年第1期1-10,共10页
Buildings are always affected by frost heave and thaw settlement in cold regions,even where saline soil is present.This paper describes the triaxial testing results of frozen silty clay with high salt content and exam... Buildings are always affected by frost heave and thaw settlement in cold regions,even where saline soil is present.This paper describes the triaxial testing results of frozen silty clay with high salt content and examines the in-fluence of confining pressure and temperature on its mechanical characteristics.Conventional triaxial compression tests were conducted under different confining pressures(0.5–7.0 MPa)and temperatures(-6℃,-8℃,-10℃,and-12℃).The test results show that when the confining pressure is less than 1 MPa,the frozen saline silty clay is dominated by brittle behavior with the X-shaped dilatancy failure mode.As the confining pressure increases,the sample gradually transitions from brittle to plastic behavior.The strength of frozen saline silty clay rises first and then decreases with increasing confining pressure.The improved Duncan-Chang hyperbolic model can describe the stress-strain relationship of frozen saline silty clay.And the parabolic strength criterion can be used to describe the strength evolution of frozen saline silty clay.The function relation of strength parameters with temperature is obtained by fitting,and the results of the parabolic strength criterion are in good agreement with the experimental results,especially when confining pressure is less than 5 MPa.Therefore,the study has important guiding significance for design and construction when considering high salinity soil as an engineering material in cold regions. 展开更多
关键词 Super saline soil frozen saline soil Triaxial compression test Confining pressure STRENGTH Deformation characteristics
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基于含冰量的冻结砂土-混凝土接触面蠕变特性 被引量:1
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作者 何菲 王旭 +4 位作者 蒋代军 周亚龙 李君善 陈航杰 陈明伟 《西南交通大学学报》 EI CSCD 北大核心 2024年第2期361-368,共8页
保证高含冰量冻土区桩基础的长期稳定性是多年冻土区桥梁桩基础安全服役中的关键问题,为研究含冰量对冻土-混凝土接触面蠕变特性的影响,采用自行研制的大型蠕变剪切仪,在−2℃条件下开展含冰量为6%、12%、16%、23%、36%、60%、80%的冻结... 保证高含冰量冻土区桩基础的长期稳定性是多年冻土区桥梁桩基础安全服役中的关键问题,为研究含冰量对冻土-混凝土接触面蠕变特性的影响,采用自行研制的大型蠕变剪切仪,在−2℃条件下开展含冰量为6%、12%、16%、23%、36%、60%、80%的冻结砂土与混凝土接触面蠕变试验.试验结果表明:在恒定的剪应力作用下,除含冰量为6%试样出现加速蠕变外,其他试样仅出现衰减蠕变及稳定蠕变2个阶段;随含冰量的增大,试样黏性变形占比增大,含冰量为80%试样的黏性变形超过总变形量的80%;稳定蠕变速率受到干密度及含冰量的综合影响,含冰量为16%时稳定蠕变速率最小;Burgers黏弹性模型能较好地模拟高含冰量冻结砂土-混凝土接触面蠕变曲线;随着含冰量的增大,初始剪切模量和稳定蠕变阶段黏滞系数先增大后减小,初始蠕变阶段的渐进剪切模量呈幂函数减小,初始蠕变阶段黏滞系数呈幂函数增大. 展开更多
关键词 高含冰量冻土 冻结砂土 接触面 蠕变试验 黏弹性模型
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Examining the Pathological Diagnostic Impact of Frozen Sections in Breast Cancer
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作者 Ying Shen 《Proceedings of Anticancer Research》 2023年第6期84-89,共6页
Objective:To analyze the diagnostic value of frozen section pathology in the diagnosis of breast cancer.Methods:A total of 50 patients with breast tumors treated between July 2021 and February 2023 were randomly selec... Objective:To analyze the diagnostic value of frozen section pathology in the diagnosis of breast cancer.Methods:A total of 50 patients with breast tumors treated between July 2021 and February 2023 were randomly selected as samples.Both paraffin section and frozen section diagnoses were conducted.The paraffin section results served as the gold standard for evaluating the value of frozen section examination.Results:Among the frozen section diagnoses,48 cases(96.00%)were confirmed,1 case was misdiagnosed(2.00%),and 1 case was delayed(2.00%).Among the confirmed patients,45 cases(90.00%)were entirely consistent,and 3 cases(6.00%)were basically consistent.The diagnostic rate of the frozen section was 96.00%,compared with 100.00%for the paraffin section(P>0.05).The diagnostic time of the frozen section(35.25±2.11 min)was significantly shorter than that for the paraffin section(6911.36±58.36 min;P<0.05).Conclusion:Frozen section diagnosis is rapid and demonstrates relatively high diagnostic accuracy.It can guide doctors in determining whether to pursue breast-conserving treatment and aid in selecting appropriate surgical methods.This is beneficial for preventing unnecessary medical interventions and reducing the need for secondary surgeries in breast cancer patients. 展开更多
关键词 frozen section diagnosis Pathological diagnosis Diagnostic results
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速冻果蔬冷冻链技术研究进展 被引量:1
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作者 伍景琼 黄嘉博 +1 位作者 高东金 于司墨 《食品工业科技》 CAS 北大核心 2024年第16期462-473,共12页
随着我国农业结构调整与居民消费水平提升,速冻果蔬越来越受到大众关注,速冻果蔬消费及其加工产品需求的持续增长也让速冻果蔬全程冷冻技术成为研究热点。本文对近年来国内外速冻果蔬冷冻链技术的研究和应用现状进行归纳分析,从物流角... 随着我国农业结构调整与居民消费水平提升,速冻果蔬越来越受到大众关注,速冻果蔬消费及其加工产品需求的持续增长也让速冻果蔬全程冷冻技术成为研究热点。本文对近年来国内外速冻果蔬冷冻链技术的研究和应用现状进行归纳分析,从物流角度综述了冷加工技术、冻藏技术、运输技术和信息技术在速冻果蔬从前端到末端全链条中的应用,介绍了应用于速冻果蔬冷冻链的新技术、新材料,总结了速冻果蔬冷冻链技术研究中存在的问题,并提出未来应从速冻果蔬冷冻链各个环节的建模仿真、冷冻链技术标准化、绿色化技术和信息技术赋能等方面进行研究,为促进我国速冻果蔬产业发展提供参考。 展开更多
关键词 冷冻链 速冻果蔬 速冻技术 信息技术 研究进展
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土壤电阻率的负温特性及冻土对接地极冲击响应的影响 被引量:1
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作者 袁涛 任健行 +3 位作者 司马文霞 常飞童 蔡永翔 肖小兵 《电工技术学报》 EI CSCD 北大核心 2024年第5期1474-1485,共12页
西藏地区由于独特的气候与地理环境,在其冻土地区存在雷电与低温共存现象。低温下冻土作为含冰复杂体系,其在雷击下的冲击散流性能仍不明晰,因此该文就冻土电阻率的负温特性以及接地极的冲击特性开展研究。首先研究了不同含水量、含盐... 西藏地区由于独特的气候与地理环境,在其冻土地区存在雷电与低温共存现象。低温下冻土作为含冰复杂体系,其在雷击下的冲击散流性能仍不明晰,因此该文就冻土电阻率的负温特性以及接地极的冲击特性开展研究。首先研究了不同含水量、含盐量的土壤电阻率随温度的变化规律;然后在冲击电流作用下,以永冻土试品的表层土壤融化厚度和季节性冻土试品的表层土壤冻结厚度为变量,探究了其对相应冻土中垂直接地极暂态电位的影响规律;最后结合冻结条件下土壤冲击放电的形貌特征与地中电场强度和电流密度的分布特性,探讨了负温下接地极暂态电位变化的本质原因。试验研究表明:考虑盐分对土壤的影响,当其温度在一次冻结温度Tf与二次冻结温度Ts之间时,电阻率随温度下降缓慢上升,只有当温度降至二次冻结温度时,才存在突增现象;在永冻土中,当冻土温度高于Ts时,接地极仍具有较好的散流性能。由此可知降低Ts可以减小水分冻结对土壤电阻率的影响,为避免极寒地区接地极失效提供了新思路。 展开更多
关键词 接地 冻土 冲击电流 极寒低温 土壤电离
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冻结重塑黏土分数阶蠕变本构模型分析 被引量:1
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作者 姚兆明 蹇膨远 +1 位作者 孔宏水 李南 《河南城建学院学报》 CAS 2024年第1期40-47,共8页
人工冻土的蠕变特性受温度场、水分场、应力场的相互影响,而传统的岩土本构模型未能考虑温度、含水率等因素。为了表达冻土介于理想固体和理想流体之间的某种“勾兑效应”,基于岩土的经验模型,将分数阶导数理论引入其中,建立受水、热、... 人工冻土的蠕变特性受温度场、水分场、应力场的相互影响,而传统的岩土本构模型未能考虑温度、含水率等因素。为了表达冻土介于理想固体和理想流体之间的某种“勾兑效应”,基于岩土的经验模型,将分数阶导数理论引入其中,建立受水、热、力三场耦合影响的人工冻土分数阶蠕变模型。将西安某煤矿黏土重塑并进行不同温度、含水率的单轴抗压和单轴蠕变试验,得到温度和含水率对冻结重塑黏土强度特性和蠕变特性的影响规律。分析冻结重塑黏土在不同负温、含水率及两种应力等级下的蠕变曲线,得到lg t-lgε曲线的线性关系,进而得出冻结重塑黏土分数阶蠕变模型相关参数与温度、含水率的函数关系。对比分数阶冻土蠕变模型试验值与计算值,发现该模型能够很好地反映冻土在不同应力等级下其蠕变随温度和含水率的变化规律,对指导寒区冻土工程设计与施工具有重要意义。 展开更多
关键词 冻结重塑黏土 蠕变试验 经验模型 分数阶导数
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