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Modelling the viscoplastic behaviour of Callovo-Oxfordian claystone with consideration of damage effect

Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 303-316页

作者： Hao Wang yu-jun cui Minh Ngoc Vu Jean Talandier Ecole des Ponts ParisTech Laboratoire Navier/CERMES6 et 8 avenue Blaise PascalMarne La Vallée cedex 277455France Andra R&D DepartmentChâtenay-Malabry92290France

In order to evaluate the performance of deep geological disposal of radioactive waste,an underground research laboratory(URL)was constructed by Andra in the Callovo-Oxfordian(COx)claystone formation at the Meuse/Haute-Marne(MHM).The construction of URL induced the excavation damage of host formations,and the ventilation in the galleries desaturated the host formation close to the gallery ***,it is expected that the mechanical behaviour of COx claystone is *** study presents a constitutive model developed to describe the viscoplastic behaviour of unsaturated and damaged COx *** this model,the unsaturation effect is considered by adopting the Bishop effective stress and the van Genuchten(VG)water retention *** terms of the viscoplastic behaviour,the nonstationary flow surface(NSFS)theory for unsaturated soils is used with consideration of the coupled effects of strain rate and suction on the yield stress.A progressive hardening law is ***,a non-associated flow rule is used,which is similar to that in Barcelona basic model(BBM).In addition,to describe the damage effect induced by suction change and viscoplastic loading,a damage function is defined based on the crack volume *** damage function contains two variables:unsaturated effective stress and viscoplastic volumetric strain,with the related parameters determined based on the mercury intrusion porosimetry(MIP)*** the model validation,different tests on COx claystone under different loading paths are *** between experimental and simulated results indicated that the present model is able to well describe the viscoplastic behaviour of damaged COx claystone,including swelling/shrinkage,triaxial extension and compression,and triaxial creep.

关键词： Callovo-Oxfordian(COx)claystone Excavation damage Time-dependent behaviour Suction Viscoplastic model

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教育数字化背景下高职院校军事理论课程资源建设研究——以长沙航空职业技术学院为例

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湖北职业技术学院学报 2024年第2期27卷 88-92,108页

作者：谭璐余翠军长沙航空职业技术学院湖南长沙410124

对高职院校军事理论课程数字资源建设现状进行调研,针对需求、机制、理论、成效四个方面分析目前军事理论课程数字资源建设存在的问题,长沙航空职业技术学院遵循军事理论课程资源建设思路,构建高职院校军事理论课程资源模型,提出“五层... 详细信息

对高职院校军事理论课程数字资源建设现状进行调研,针对需求、机制、理论、成效四个方面分析目前军事理论课程数字资源建设存在的问题,长沙航空职业技术学院遵循军事理论课程资源建设思路,构建高职院校军事理论课程资源模型,提出“五层”原则设计、“六阶”步骤规划、“五化”路径探索的三维结构,提高高职院校的国防教育质量。

关键词：军事理论课课程资源建设定向培养军士学员

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Effect of water chemistry on the hydro-mechanical behaviour of compacted mixtures of claystone and Na/Ca-bentonites for deep geological repositories

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 527-536页

作者： Zhixiong Zeng yu-jun cui Jean Talandier Laboratoire Navier/CERMES Ecole des Ponts ParisTechMarne La Vallée77455France French National Radioactive Waste Management Agency(Andra) Châtenay-Malabry92298France

In the French deep geological disposal for radioactive wastes,compacted bentonite/claystone mixtures have been considered as possible sealing *** emplacement in place,such mixtures are hydrated by the site solution as well as the cement solution produced by the degradation of *** this study,the effects of synthetic site solution and cement solution on the hydro-mechanical behaviour of compacted mixtures of claystone and two types of bentonites(MX80 Na-bentonite and Sardinia Cabentonite)were investigated by carrying out a series of swelling pressure,hydraulic conductivity and mercury intrusion porosimetry(MIP)*** was found that for the MX80 bentonite/claystone mixture hydrated with synthetic site solution,the swelling capacity was reduced compared to the case with deionised water owing to the transformation of Na-montmorillonite to multi-cation dominant montmorillonite by cation *** the Sardinia bentonite/claystone mixture,the similar increasing rate of swelling pressure was observed during the crystalline swelling process for different solutions,suggesting insignificant cation ***,the cations in the synthetic site solution could reduce the thickness of diffuse double layer and the osmotic swelling for both MX80 bentonite/claystone and Sardinia bentonite/claystone *** large-pore volume increased consequently and enhanced water *** the cement solution,the hydroxide could also dissolve the montmorillonite,reducing the swelling pressure,and increase the large-pore volume,facilitating the water ***,the decrease of swelling pressure and the increase of hydraulic conductivity were more significant in the case of low dry density because of more intensive interaction between montmorillonite and hydroxide due to the high permeability.

关键词： Bentonite/claystone mixture Synthetic site solution Cement solution Bentonite type Swelling pressure Hydraulic conductivity

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Determining osmotic suction through electrical conductivity for unsaturated low-plasticity soils

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第6期14卷 1946-1955页

作者： Zi Ying Nadia Benahmed yu-jun cui Myriam Duc Ecole des Ponts ParisTech Laboratoire Navier/CERMES6-8 Av.Blaise PascalCitéDescartesChamps-sur-MarneMarne-la-ValléeCedex277455France INRAE Aix Marseille UniversityUnitéde Recherche RECOVER3275 Route CézanneAix-en-Provence13182France UniversitéGustave Eiffel IFSTTAR/GERS/SRO14-20 Boulevard NewtonChamps-sur-MarneMarne-la-Vallée77447France

Determining osmotic suction from the electrical conductivity(EC)of soil pore water was widely reported in the ***,while dealing with unsaturated soils,they do not have enough soil pore water to be extracted for a reliable measurement of *** this paper,the chilled-mirror dew-point hygrometer and contact filter paper method were used to determine the total and matric suctions for low-plasticity soils with different salinities(0.05‰,2.1‰,and 6.76‰).A new piecewise function was proposed to calculate the osmotic suction,with the piecewise point corresponding to the first occurrence of precipitated salt in mixed salt solutions(synthetic seawater).EC,ion and salt concentrations used for osmotic suction calculation were transformed from the established relationships of mixed salt solution instead of experimental *** calculated osmotic suction by the proposed equation and the equations in the literature was compared with the indirectly measured one(the difference between the measured total and matric suctions).Results showed that the calculated osmotic suction,especially the one calculated using the proposed function,was in fair agreement with the indirectly measured data(especially for specimens with higher salinity of 6.76‰),suggesting that the transformation of EC and concentrations from the established relationship is a good alternative to direct measurement for lowplasticity *** particular,the proposed method could be applied to unsaturated low-plasticity soils which do not have enough soil pore water for a proper EC measurement.

关键词： Unsaturated soils Mixed salt solutions Osmotic suction Electrical conductivity(EC)

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Progress on the glassy-crystal laminates:From design,microstructure to deformation and future solutions

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Journal of Materials Science & Technology 2024年第5期172卷 113-144页

作者： yu Chen Ronggao cui jun Shen Gang Wang College of Mechatronics and Control Engineering Shenzhen UniversityShenzhen 518060China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Department of Motor Design Business Weichai New Energy Technology Co.Ltd.Weifang 261061China Guangdong Key Laboratory of Electromagnetic Control and Intelligent Robots Shenzhen UniversityShenzhen 518060China Laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghai 200444China

The development of new design strategies to create innovative structural materials,refine existing ones,and achieves compatible combinations of strength and plasticity remains a worldwide *** alloys,such as shape memory alloys(SMAs),bulk metallic glasses(BMGs),high entropy alloys(HEAs),and heterogeneous pure metals such as Cu,have excellent mechanical responses,but they still fall short of meeting all the requirements of structural materials due to specific flaws,such as lack of tensile de-formation for BMGs and low yielding strength for *** address these shortcomings,proposals such as integrating glassy matrices and crystallized alloys,such as HEAs/SMAs,have been ***,these solutions have unresolved issues,such as the challenging control of B2 phase formation in BMG ***,glass-crystal(A/C)laminated alloys with alternating layers have been reported to exhibit improved mechanical properties and activated work-hardening behaviors,but they still face press-ing issues such as bonding interfaces and unknown deformation *** review focuses on design routes such as the selection of alloy components and processing techniques,exploration of micro-structural evolution and deformation modes with an increase in strain,and future solutions to address pressing and unsolved *** prominent advantages include diversified deformation mechanisms,such as deformation twinning,martensitic phase transformation,and precipitation hardening,as well as tuned interactive reactions of shear bands(SBs)near the A/C ***,this review provides a promising pathway to design and develop structural materials in the materials field community.

关键词： Glassy-crystal laminates Bulk metallic glasses High entropy alloys Shape memory alloys Microstructure Deformation mechanisms Future solutions

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On the hydro-mechanical behaviour of MX80 bentonite-based materials

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第3期9卷 183-192页

作者： yu-jun cui Ecole des Ponts ParisTech Laboratoire Navier/CERMES 6e8 av. Blaise Pascal Cité Descartes Champs e sur e Marne 77455 Marne-la=Valléecedex 2France

Bentonite-based materials have been considered in many countries as engineered barrier/backfilling materials in deep geological disposal of high-level radioactive *** the long period of waste storage,these materials will play an essential role in ensuring the integrity of the storage system that consists of the waste canisters,the engineered barrier/backfill,the retaining structures as well as the geological ***,it is essential to well understand the hydro-mechanical behaviours of these bentonite-based *** review paper presents the recent advances of knowledge on MX80 bentonite-based materials,in terms of water retention properties,hydraulic behaviour and mechanical *** is put on the effect of technological voids and the role of the dry density of *** swelling anisotropy is also discussed based on the results from swelling tests with measurements of both axial and radial swelling pressures on a sand-bentonite mixture compacted at different *** observation was used to help the interpretation of macroscopic hydromechanical ***,the evolution of soil microstructure thus the soil density over time is discussed based on the results from mock-up *** evolution is essential for understanding the longterm hydro-mechanical behaviour of the engineered barrier/backfill.

关键词： Bentonite-based materials Water retention Hydraulic conductivity Mechanical behaviour Microstructure Dry density evolution

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Geometry characteristics and wide temperature behavior of silicon-based GaN surface acoustic wave resonators with ultrahigh quality factor

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Science China(Information Sciences) 2024年第2期67卷 267-278页

作者： Guofang yu Renrong LIANG Haiming ZHAO Lei XIAO Jie cui yue ZHAO Wenpu cui Jing WANG jun XU jun FU Tianling REN School of Integrated Circuits Tsinghua University Beijing National Research Center for Information Science Technology Tsinghua University

Surface acoustic wave(SAW) resonators with an ultrahigh Q-factor are designed and fabricated on silicon-based gallium nitride(GaN/Si). The temperature-dependent performance is characterized over a wide range, from 10 to 500 K. Finite element analysis is employed to guide the design of the SAW resonator from indications of the Rayleigh mode and weak propagation direction dependence of SAW in the c-plane of GaN/Si. The SAW resonator with 100 pairs of interdigital transducers(IDT), 100 pairs of grating reflectors(GR) for each side, aperture size of 80 μm, metallization ratio of 0.5, and electrode width of 500 nm resonates at 1.9133 GHz accordingly with an ultrahigh Q-factor of 7622 at room temperature, which contributes the fr× Qr, up to 14.583×1012Hz. A resonator operating over 10 to 500 K indicates an approximately linear decreasing temperature dependence above 280 K while being approximately constant below 40 K. The fitting to resonator characteristics using the modified Butterworth Van Dyke(m BVD) model reveals a reduction in both the electrode and mechanical losses while worsening the dielectric loss with cooling down.

关键词： GaN/Si SAW resonator ultrahigh Q-factor temperature-dependent performance mBVD losses

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Determining the soil-water retention curve using mercury intrusion porosimetry test in consideration of soil volume change

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第5期12卷 1070-1079页

作者： Wen-Jing Sun yu-jun cui State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Department of Civil Engineering School of Mechanics and Engineering ScienceShanghai UniversityShanghai200444China Ecole des Ponts ParisTech Laboratoire Navier/CERMES6e8 avenue Blaise PascalCitéDescartesChamps-sur-MarneMarne-la-Vallée cedex 277455France Institute for the Conservation of Cultural Heritage Shanghai200444China

It is well-known that a close link exists between soil-water retention curve(SWRC)and pore size distribution(PSD).Theoretically,mercury intrusion porosimetry(MIP)test simulates a soil drying path and the test results can be used to deduce the SWRC(termed SWRCMIP).However,SWRCMIP does not include the effect of volume change,compared with the conventional SWRC that is directly determined by suction measurement or suction control *** deformable soils,there is a significant difference between conventional SWRC and *** this study,drying test was carried out on a reconstituted silty soil,and the volume change,suction,and PSD were measured on samples with different water *** change in the deduced SWRCMIP and its relationship with the conventional SWRC were *** results showed that the volume change of soil is the main reason accounting for the difference between conventional SWRC and *** on the test results,a transformation model was then proposed for conventional SWRC and SWRCMIP,for which the soil state with no volume change is taken as a *** between the experimental and predicted SWRCs showed that the proposed model can well consider the influence of soil volume change on its water retention property.

关键词： Soil-water retention curve(SWRC) Mercury intrusion porosimetry(MIP) Pore size distribution(PSD) Deformable soils

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Assessment of the methods for determining net radiation at different time-scales of meteorological variables

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 239-246页

作者： Ni An Sahar Hemmati yu-jun cui Ecole des Ponts ParisTech Laboratoire Navier/CERMES6e8 av. Blaise PascalCité DescartesChamps sur Marne77455 Marne la ValléeFrance Université Paris-Est IFSTTARGERS14e20 Boulevard NewtonCité DescartesChamps sur Marne77447 Marne la ValléeFrance

When modeling the soil/atmosphere interaction,it is of paramount importance to determine the net radiation *** are two common calculation methods for this *** 1 relies on use of air temperature,while Method 2 relies on use of both air and soil ***,there has been no consensus on the application of these two *** this study,the half-hourly data of solar radiation recorded at an experimental embankment are used to calculate the net radiation and long-wave radiation at different time-scales(half-hourly,hourly,and daily) using the two *** results show that,compared with Method 2 which has been widely adopted in agronomical,geotechnical and geo-environmental *** 1 is more feasible for its simplicity and accuracy at shorter ***,in case of longer time-scale,daily for instance,less variations of net radiation and long-wave radiation are obtained,suggesting that no detailed soil temperature variations can be *** other words,shorter time-scales are preferred in determining net radiation flux.

关键词： Energy balance Net radiation Different time-scales Meteorological data

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Missing microbes in infants and children in the COVID-19 pandemic:a study of 1,126 participants in Beijing,China

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Science China(Life Sciences) 2024年第8期67卷 1739-1750页

作者： Jiejing Wang yuejuan Li yu Mu Kefei Huang Danyi Li Canhui Lan yutao cui jun Wang CAS Key Lab for Pathogenic Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Beijing Dr.cuiyuTAO Clinic Beijing 100028China R-Institute Co.Ltd. Beijing 100011China

The COVID-19 pandemic has caused many fatalities worldwide and continues to affect the health of the recovered patients in the form of *** this study,we compared the gut microbiome of uninfected infants and children before the pandemic began(BEFORE cohort,n=906)to that of after the pandemic(AFTER cohort,n=220)to examine the potential impact of social distancing and life habit changes on infant/children gut *** on 16S rRNA sequencing,we found a significant change in microbiome composition after the pandemic,with Bacteroides enterotype increasing to 35.45%from 30.46%before the *** quantification indicated that the bacterial loads of seven keystone taxa decreased by 91.69%–19.58%.Quantitative microbiome profiling,used to enhance the resolution in detecting microbiome differences,revealed a greater explained variance of pandemic on microbiome compared to gender,as well as a significant decrease in bacterial loads in 15 of the 20 major *** random forest age-predictor indicated the gut microbiomes were less mature in the after-pandemic cohort than in the before-pandemic cohort in the children group(3–12 years old)and had features of a significantly younger age(average of 1.86 years).Lastly,body weight and height were significantly lower in the after-pandemic cohort than in the before-pandemic cohort in infants(<1 year of age),which was associated with a decrease in bacterial loads in the fecal microbiome.

关键词： gut microbiome COVID-19 pandemic quantitative microbiome profiling children health

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