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Science china(Technological Sciences) 2005年第Z1期48卷 53-64页

作者： zhang lei1,{1.,{2.,2.& wang yuannian1 1. institute of mechanics, Chinese Academy of Sciences, beijing 1.0080, china 2. Graduate School, Chinese Academy of Sciences, beijing 1.0060, china institute of {1. Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100060 China

This paper studies the effect of fissure water pressure in different fractures on the critical angle of landslide by laboratory investigation and numerical simulation in order to understand the mechanisms of fissure water pressure on landslide stability. Laboratory observations show that the effect of fissure water pressure on the critical angle of landslide is little when the distance between water-holding fracture and slope toe is three times greater than the depth of fissure water. These experimental results are also simulated by a three-dimensional face-to-face contact discrete element method. This method has included the fissure water pressure and can accurately calculate the critical angle of jointed slope when fissure water pressure in vertical sliding surface exists. Numerical results are in good agreement with experimental observations. It is revealed that the location of water-holding structural surface is important to landslide stability. The ratio of the distance between water-holding fissure and slope toe to the depth of fissure water is a key parameter to justify the effect of fissure water pressure on the critical angle of landslide.

关键词： jointed rock slope, discrete element method, fracture in vertical sliding surface, model experiment,fissure water pressure.

Stochastic structural model of rock and soil aggregates by continuum-based discrete element method

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Science china(Technological Sciences) 2005年第Z1期48卷 95-106页

作者： wang {1., ZHAO Manhong1. li {2. & J.G. wang2.. institute of mechanics, Chinese Academy of Sciences, beijing 1.0080, china 2. Tropical Marine Science institute, National University of Singapore, 1. Kent Ridge Crescent, Singapore 1.92.0 institute of {1. Chinese Academy of Sciences Beijing China Tröpical Marine Science institute National University of Singapore Singapore

This paper first presents a stochastic structural model to describe the random geometrical features of rock and soil aggregates. The stochastic structural model uses mixture ratio, rock size and rock shape to construct the microstructures of aggregates, and introduces two types of structural elements (block element and jointed element) and three types of material elements (rock element, soil element, and weaker jointed element) for this microstructure. Then, continuum-based discrete element method is used to study the deformation and failure mechanism of rock and soil aggregate through a series of loading tests. It is found that the stress-strain curve of rock and soil aggregates is nonlinear, and the failure is usually initialized from weaker jointed elements. Finally, some factors such as mixture ratio, rock size and rock shape are studied in detail. The numerical results are in good agreement with in situ test. Therefore, current model is effective for simulating the mechanical behaviors of rock and soil aggregates.

关键词： CDEM, rock and soil aggregate, mixture ratio.

Experimental and discrete element numerical analysis of side slope instability induced by fissure water underlying impervious bed

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Science china(Technological Sciences) 2005年第Z1期48卷 65-80页

作者： liU Bingshan1, li shihai1, zhang lei1,{2. {2. Jianguo31. institute of mechanics, Chinese Academy of Sciences, beijing 1.0080, china 2. Graduate School, Chinese Academy of Sciences, beijing 100060, china 3. Tropical Marine Science institute, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192.0 institute of {1. Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100060 China Tropical Marine Science institute National University of Singapore 10 Kent Ridge Crescent Singapore 119260 Singapore

When the sliding mass contains impervious bed, rainfall can infiltrate into mountain via crevices and form higher artesian aquifer at impervious bed inferior. This will decrease slip resistance and increase sliding forces of the sliding mass, thus lowering the safety factor, and inducing landslide disasters. In this paper, a landslide experimental apparatus is designed for experimental studies on the mechanism of this type of landslides. Meanwhile, the non-dimensional parameters in the model experiment are taken into account using dimensional analysis. The experimental results show that (1. the ratio of the cleft water pressure to the overlying pressure is a crucial parameter affecting the stability of the slope; (2. when the shut-in pressure reaches 80% of the normal component of the pressure on the slip surface made up of rock and soil, landslide will occur; (3) the whole slope will start to slide when the shut-in pressure is equal to the normal component of the pressure formed by the overlying rock and soil on the upper 30% area. In this article, a discrete element method simulation is used to investigate the influence of cleft water pressure and shearing strength on the landslide stability. It can be concluded that the critical value of Ccr, ?cr, which determines the slide mass stability, increases with the increase of the water pressure; if the water pressure reaches a high level, the stability of the slide mass depends mainly on C, while the influence of ? becomes smaller than C.

关键词： impervious bed, rainfall infiltration, pore water pressure, landslide experiment, displacement monitor, discrete element method.

Electronic structure and magnetic properties of metastable SmCo_(7) compound

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Science china(Physics,{1. & Astronomy) 2005年第3期48卷 325-335页

作者： zhang Changwen 1 , li Hua 1 , DONG Jianmin 1 , wang Yongjuan 1 , PAN Fengchun 1 , zhang Jian 1 , GUO Yongquan 2.& li Wei 2.1. School of Physics and Microelectronics, Shandong University, Jinan 2.0100, china 2. institute of Functional Materials, Central Iron and Steel Research institute, beijing 100081, china School of Physics and Microelectronics Shandong University Jinan China institute of Functional Materials Central Iron and Steel Research Institutes Beijing China

The electronic density of states, spin-splittings and atomic magnetic moments of SmCo 7 compound have been studied using spin-polarized MS-Xα method. The results show that a few of electrons are transferred to Sm(5d 0 ) orbital because of orbital hybridization between Sm and Co atoms in the compound. The exchange interactions between 3d and 5d electrons lead to the magnetic coupling between Sm and Co, and therefore, result in the long-range ferromagnetic order inside the SmCo 7 compound. There are negative exchange couplings occurring at some levels, which weakens the strength of average coupling around Co lattice. So, the Curie temperature and Co-moment of SmCo 7 decrease distinctly compared with pure Co. Compared with SmCo 5 compound, the disordered substitution of Co-Co “dumbbell-atom” pairs for Sm changes the local environment of Co lattice, which makes the 2. site bear negative magnetic moment. The strength of hybridization near Fermi level weakens and the free energy of the compound increases obviously. Thus, SmCo 7 is a metastable compound at room temperature. Considering the localization of 4f electrons and a few of 5d electrons arising from the orbital hybridization, the magnetic moment of Sm atom will be 1.61. B in SmCo 7 compound, which is in agreement with the experimental values of Sm 3+ ion- moment and Sm atom-moment in metals.

关键词： electronic structure, spin polarization, atomic magnetic moment, exchange coupling, Curie temperature.

The properties of halo structure for ^(1.)B

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Science china(Physics,{1. & Astronomy) 2008年第7期51卷 781-787页

作者： HU ZhengGuo1, wang Meng1, XU HuShan1, SUN ZhiYu1, wang JianSong1, XIAO GuoQing1, ZHAN WenLong1, XIAO ZhiGang1, MAO RuiShi1,2. li Chen1, {2. XueYing1,2. {2. HongBin1, ZHAO TieCheng1, XU ZhiGuo1, wang Yue1,2. CHEN RuoFu1,2. HUANG TianHeng1,2. FU Fen1,2. GAO Qi1,2. HAN JianLong1,2. {2. XueHeng1,2. ZHENG Chuan1,2. YU YuHong1,2.& GUO ZhongYan1 1 institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, china 2.Graduate University of the Chinese Academy of Sciences, beijing 100049, china institute of Modern Physics Chinese Academy of Sciences Lanzhou China Graduate University of the Chinese Academy of Sciences Beijing China

The total reaction cross section (1.2.±93 mb) of 1.B at the energy of 43.7 A MeV on C target has been measured by using the transmission method at the Radioactive Ion Beam {1.ne in Lanzhou (RIBLL). Assuming 1.B consists of a core 1.B plus two halo neutrons,the total cross section of 1.B on C target was calculated with the zero-range Glauber model,where double Gaussian density distributions and Gaussian plus HO density distributions were used. It can fit the experimental data very well. The characteristic of halo structure for 1.B was found with a large diffusion of the neutrons density distribution.

关键词： total cross section density distribution Glauber model the characteristic of halo structure

Fabricating bio-inspired high impact resistance carbon nanotube network films for multi-protection under an extreme environment

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Nano Research 2024年第9期17卷 7793-7802页

作者： Mingquan Zhu Kailu Xiao Wei zhang Xudong {1. Yunxiang Bai Shijun {2. Peng zhang Feng Gao Congying {2. Wenqiang Xu Huiyong li Xianqian Wu Chao {2. Hui zhang Luqi liu Zhong zhang CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Materials Science and Engineering Texas A&M UniversityCollege StationTexas 77840USA institute of {1. Chinese Academy of SciencesBeijing 100190China School of Astronautics Harbin Institute of TechnologyHarbin150001China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

The fabrication of light-weight,highly impact-resistant,and energy-absorbent materials is urgently demanded in many facets of the society from body armor to aerospace engineering,especially under an extreme *** nanotubes(CNTs),one of the strongest and toughest materials ever found,also have good conductivity,chemical stability,and thermal stability,etc,making them a competitive candidate as building blocks to help achieve the above *** this work,a kind of CNT network was prepared by using chlorosulfonic acid(CSA)to release the internal stress of super-aligned carbon nanotube films(SA-CNTF)and dendritic polyamide amine(PAMAM)to further introduce multiple hydrogen bonds and interlocking *** fabricated bioinspired carbon nanotube network films(PAMAM@C-CNTF)have a high toughness of 45.97 MJ/m3,showing an increase of 42.%compared to neat *** importantly,the anti-impact performance of the films(e.g.,with a maximum specific energy absorption of 1.40 MJ/kg under 80-1.0 m/s projectile impact)is superior to that of conventional protective materials from steel and Kevlar fiber,and also exceeds that of any other reported carbon-based *** hierarchical energy dissipation mechanism was further revealed through experiment and *** functions including intelligent heating/anti-icing,ultraviolet protection,as well as electromagnetic interference shielding properties make these network films have great potential in practical multi-protection applications,especially under an extreme environment.

关键词： carbon nanotubes composites mechanical properties multi-function

Global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback

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Science china(Technological Sciences) 2010年第3期53卷 595-607页

作者： zhang li1,wang Huai{2. & HU HaiYan1,2.1 MOE Key Lab of mechanics and Control of Aerospace Structures,Nanjing University of Aeronautics and Astronautics,Nanjing 2.0016,china 2.School of Aerospace Engineering,beijing institute of Technology,beijing 100081,china MOE Key Lab of mechanics and Control of Aerospace Structures Nanjing University of Aeronautics and Astronautics Nanjing China School of Aerospace Engineering Beijing Institute of Technology Beijing China

This paper presents both analytical and numerical studies on the global view of Hopf bifurcations of a van der Pol oscillator with delayed state *** on a detailed analysis of the stability switches of the trivial equilibrium of the system,the stability charts are given in a parameter space consisting of the time delay and the feedback *** center manifold reduc-tion and the normal form method are used to study Hopf bifurcations with respect to the time *** gain an insight into the persistence of a Hopf bifurcation as the time delay varies farther away from its critical value,the method of multiple scales is used to obtain the global view of Hopf bifurcations with respect to the time *** the analytical results of Hopf bifurca-tions and global view of those bifurcations are validated via a collocation scheme implemented on *** most important discovery in this paper is the well-structured global view of Hopf bifurcations for the system of concern,showing the generality of the persistence of Hopf bifurcations.

关键词： Hopf bifurcation global view center manifold reduction method of multiple scales collocation scheme

Generation of surface electrons in femtosecond laser-solid interactions

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Science china(Physics,{1. & Astronomy) 2006年第3期49卷 335-340页

作者： XU Miaohua1. li Yutong1. YUAN Xiaohui1.{1. ZHENG Zhiyuan1. lianG Wenxi1. YU Quanzhi1. zhang Yi1. {{1. Zhaohua1. WEI Zhiyi1.& zhang Jie1.1. Key Laboratory of Optical Physics, institute of Physics, Chinese Academy of Sciences, beijing 1.0080, china {1. State Key Laboratory of Transient Optics Technology, Chinese Academy of Sciences, Xi’an 71.068, china Key Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing China State Key Laboratory of Transient Optics Technology Chinese Academy of Sciences Xi’an China

The characteristics of hot electrons produced by p-polarized femtosecond laser-solid interactions are studied. The experimental results show that the outgoing electrons are mainly emitted in three directions: along the target surface, the normal direction and the laser backward direction. The electrons flowing along the target surface are due to the confinement of the electrostatic field and the surface magnetic field, while the electrons in the normal direction due to the resonant absorption.

关键词： hot electrons,surface magnetic field,femtosecond laser pulses

Compression behavior of Zr_(41.Ti_(1.)Cu_(1.0}5)Ni_(1.)Be_(2..5) bulk metallic glass up to 2. GPa

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Science china(Physics,{1. & Astronomy) 2005年第3期48卷 319-324页

作者： li Gong 1, 2., ZHAN Zaiji 2., liU Jing 3 , YUN Jinku 1 , SUN liling 2., liU Riping 1 , zhang Jun 2.& {2. Wenkui 1, 2.1. Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004,{2. 2. Center for Condensed Matter Physics, institute of Physics, Chinese Academy of Sciences, beijing 1.0080,{2. 3. BSRF, institute of High Energy Physics, Chinese Academy of Sciences, beijing 100039,{2. Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao China Center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China BSRF Institute of High Energy Physics Chinese Academy of Sciences Beijing China

The compression of a Zr41.i1.Cu1.0}5Ni1.Be2..5 bulk metallic glass (BMG) is investigated at room temperature up to 2. GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.

关键词： bulk metallic glass, high pressure, structural relaxation, synchrotron radiation.

Investigation of stress-induced progressive failure of mine pillars using a Voronoi grain-based breakable block model

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International Journal of Mining Science and Technology 2024年第5期34卷 713-729页

作者： Shili Qiu Shirui {1. Quan Jiang Shaojun li Hao {1. Qiankuan {2. State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The Voronoi grain-based breakable block model(VGBBM)based on the combined finite-discrete element method(FDEM)was proposed to explicitly characterize the failure mechanism and predict the deformation behavior of hard-rock mine *** influence of the microscopic parameters on the macroscopic mechanical behavior was investigated using laboratory-scale *** field-scale pillar models(width-to-height,W/H=1.{1.and 3)were calibrated based on the empirically predicted stress-strain curves of Creighton mine *** results indicated that as the W/H ratios increased,the VGBBM effectively predicted the transition from strain-softening to pseudo-ductile behavior in pillars,and explicitly captured the separated rock slabs and the V-shaped damage zones on both sides of pillars and conjugate shear bands in core zones of *** volumetric strain field revealed significant compressional deformation in core zones of *** the peak strains of W/H=1.and {1.pillars were relatively consistent,there were significant differences in the strain energy storage and release mechanism.W/H was the primary factor influencing the deformation and strain energy in the pillar *** friction coefficient of the structural plane was also an important factor affecting the pillar strength and the weakest discontinuity *** fracture surface was controlled by the discontinuity angle and the friction *** study demonstrated the capability of the VGBBM in predicting the strengths and deformation behavior of hard-rock pillars in deep mine design.

关键词： Pillar strength FDEM Voronoi tessellation Spalling Bulking