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Preliminary study on interaction between plant frictional root and rock-soil mass

Science china(Technological Sciences) 2010年第7期53卷 1938-1942页

作者： YAN ZhiXin1’2, SONG Yun3. JIANG Ping1’2 & WANG HouYu4 1 Key Laboratory of mechanics on Disaster and Environment in Western china (lanzhou University), Ministry of Education,{3., china 2 school of civil engineering and mechanics, lanzhou University,{3., china 3.College of civil engineering and mechanics, Central South University of Forestry and Technology, Changsha 410004, china 4 Air Force engineering Design & Research Bureau, Beijing 100077, china Key Laboratory of mechanics on Disaster and Environment in Western china (lanzhou University) Ministry of Education Lanzhou China school of civil engineering and {3. Lanzhou University Lanzhou China College of civil engineering and mechanics Central South University of Forestry and Technology Changsha China Air Force engineering Design & Research Bureau Beijing China

The interaction between lateral root system of woody plant and soil mass is similar to the one between shrub, herbage and soil mass, and has the effect of frictional reinforcement on slope soil. It plays an important role in reinforcing soil strength in shallow slope. Therefore, slope soil mass can be considered as a composite of soil and plant roots and the soil strength and stability of shallow slope soil mass are improved. However, current researches still remain on the level of qualitatively analyzing the relation between root and soil mass. In this paper, some exploratory researches on quantitative analysis of the interaction mechanism between root and soil mass are conducted. With the study of interaction between herbage root system (lateral root system of woody plants) and soil mass, the mechanical model of interaction between frictional root and soil mass is established. The accuracy of the model is verified by field experiments of Pinus Yunnanensis. The mechanical model provides a crucial theoretical guidance to quantitatively analyzing the interaction between plant root and soil mass; it also has certain values in application.

关键词： plant slope protection vegetation for slope protection mechanical model frictional root

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Guided wave propagation in multilayered piezoelectric structures

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Science china(Physics,mechanics & Astronomy) 2009年第7期52卷 1094-1104页

作者： GUO YongQiang1, CHEN WeiQiu2,3.& ZHANG YongLiang4 1 Key Laboratory of mechanics on Disaster and Environment in Western china, Ministry of Education, and school of {3. engineering and mechanics, lanzhou University, lanzhou 73.000, china 2 Key Laboratory of Soft Soils and Geoenvironmental engineering, Ministry of Education, and Department of {3. engineering, Zhejiang University, Hangzhou 3.0058, china 3.Department of engineering mechanics, Zhejiang University, Hangzhou 3.0027, china 4 school of {3. engineering, lanzhou Jiaotong University, lanzhou 73.070, china Key Laboratory of mechanics on Disaster and Environment in Western china Ministry of Education and School of Civil Engineering and Mechanics Lanzhou University Lanzhou China Key Laboratory of Soft Soils and Geoenvironmental engineering Ministry of Education and Department of Civil Engineering Zhejiang University Hangzhou China Department of engineering mechanics Zhejiang University Hangzhou China school of civil engineering Lanzhou Jiaotong University Lanzhou China

A general formulation of the method of the reverberation-ray matrix (MRRM) based on the state space formalism and plane wave expansion technique is presented for the analysis of guided waves in multilayered piezoelectric structures. Each layer of the structure is made of an arbitrarily anisotropic piezoelectric material. Since the state equation of each layer is derived from the three-dimensional theory of linear piezoelectricity, all wave modes are included in the formulation. Within the framework of the MRRM, the phase relation is properly established by excluding exponentially growing functions, while the scattering relation is also appropriately set up by avoiding matrix inversion operation. Consequently, the present MRRM is unconditionally numerically stable and free from computational limitations to the total number of layers, the thickness of individual layers, and the frequency range. Numerical examples are given to illustrate the good performance of the proposed formulation for the analysis of the dispersion characteristic of waves in layered piezoelectric structures.

关键词： multilayered piezoelectric structures the method of reverberation-ray matrix guided waves dispersion characteristic

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A computer simulation of nucleation and growth of thin films

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Science china(Physics,mechanics & Astronomy) 2004年第4期47卷 442-451页

作者： ZHENG Xiaoping1,ZHANG Peifeng2,HE Deyan2,LIU Jun2& MA Jiantai3.1. Key Laboratory of Opto-Electronic Technology and Intelligent Control, Ministry of Education, lanzhou Jiaotong University, lanzhou 73.070, china 2. {3. of Physical Science and Technology, lanzhou University, lanzhou 73.000, china 3. {3. of Chemistry and Chemistry engineering, lanzhou University, lanzhou 73.000, china Key Laboratory of Opto-Electronic Technology and Intelligent Control Ministry of Education Lanzhou Jiaotong University Lanzhou China school of Physical Science and Technology Lanzhou University Lanzhou China school of Chemistry and Chemistry engineering Lanzhou University Lanzhou China

A three-dimensional kinetic Monte Carlo technique has been developed for simulating the nucleation and growth of thin films. This model involves incident atom attachment, surface diffusion of the atoms on the growing surface and atom detachment from the growing surface. It takes some new effects into account, such as a significant improvement in calculation of activation energy for the atom diffusion, which renders the model more reasonable. In addition three optimum temperatures and the consistency of their dependence on deposition rate have been found out; the dependence of the surface roughness and relative density on the deposition rate has been discussed; and the approximation of freezing neighbour atoms and periodic boundary conditions has been applied.

关键词： Monte Carlo, thin film, nucleation, surface roughness, relative density.

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Performance-based methodology for assessing seismic vulnerability and capacity of buildings

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Earthquake engineering and engineering Vibration 2010年第2期9卷 157-165页

作者： Lin Shibin1, Xie Lili1, 2,Gong Maosheng1,2 and Li Ming1,3.1.Institute of engineering mechanics,china Earthquake Administration, Harbin 150080,{3. 2.school of civil engineering,Harbin Institute of Technology,Harbin 150090,{3. 3.school of civil engineering,Shenyang Jianzhu University,Shenyang 11016,{3. Institute of engineering mechanics China Earthquake Administration Harbin China school of civil engineering Harbin Institute of Technology Harbin China school of civil engineering Shenyang Jianzhu University Shenyang China

This paper presents a performance-based methodology for the assessment of seismic vulnerability and capacity of buildings. The vulnerability assessment methodology is based on the HAZUS methodology and the improved capacity- demand-diagram method. The spectral displacement (Sd) of performance points on a capacity curve is used to estimate the damage level of a building. The relationship between Sd and peak ground acceleration (PGA) is established, and then a new vulnerability function is expressed in terms of PGA. Furthermore, the expected value of the seismic capacity index (SCev) is provided to estimate the seismic capacity of buildings based on the probability distribution of damage levels and the corresponding seismic capacity index. The results indicate that the proposed vulnerability methodology is able to assess seismic damage of a large number of building stock directly and quickly following an earthquake. The SCev provides an effective index to measure the seismic capacity of buildings and illustrate the relationship between the seismic capacity of buildings and seismic action. The estimated result is compared with damage surveys of the cities of Dujiangyan and Jiangyou in the M8.0 Wenchuan earthquake, revealing that the methodology is acceptable for seismic risk assessment and decision making. The primary reasons for discrepancies between the estimated results and the damage surveys are discussed.

关键词： performance-based vulnerability building damage seismic capacity software HAZUS

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SINGULAR BEHAVIORS OF INTERFACIAL CRACKS IN 2D MAGNETOELECTROELASTIC BIMATERIALS

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Acta Mechanica Solida Sinica 2009年第3期22卷 232-239页

作者： Cuiying Fan1 Youhe Zhou1 Han Wang2 Minghao Zhao1,2(1Key Laboratory of mechanics on Disaster and Environment in Western china,the Ministry of Education of china,and Department of mechanics and engineering Science,College of civil engineering and mechanics,lanzhou University,lanzhou 73.000,china)(2school of Mechanical engineering,Zhengzhou University,Zhengzhou 450001,china) Key Laboratory of mechanics on Disaster and Environment in Western china the Ministry of Education of China and Department of Mechanics and Engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou China school of Mechanical engineering Zhengzhou University Zhengzhou China

The singular characteristics of stress,electric displacement and magnetic induction fields near the tip of impermeable interfacial cracks in two-dimensional magnetoelectroelastic bimaterials are studied using the generalized Stroh *** types of singularities are ob-tained:one is the oscillating singularity 1/2±iε,the other is the non-oscillating singularity 1/2±κ.It is found that the non-zero parameters ε and κ cannot coexist for one transversely isotropic MEE bimaterial,a similar result is obtained for transversely isotropic piezoelectric bimaterials.

关键词： generalized Stroh formalism magnetoelectroelastic bimaterial interfacial crack singularity index

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Analysis theory of random energy of train derailment in wind

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Science china(Physics,mechanics & Astronomy) 2010年第4期53卷 751-757页

作者： CHEN RuiLin 1,2,3., ZENG QingYuan 3., HUANG YunQing 1 , XIANG Jun 3., WEN Ying 3., GUO XiaoGang 2 , YIN ChangJun 2 , DONG Hui 2 & ZHAO Gang 4 1 Hunan Key Laboratory for Computation and Simulation in Science and engineering, Xiangtan University, Xiangtan 411105, china 2 school of {3. engineering & mechanics, Xiangtan University, Xiangtan 411105, china 3.school of {3. Architecture, Central South University, Changsha 410075, china 4 AMEC, Toronto M5A5G7, Canada Hunan Key Laboratory for Computation and Simulation in Science and engineering Xiangtan University Xiangtan China school of civil engineering & {3. Xiangtan University Xiangtan China school of civil Architecture Central South University Changsha China AMEC Toronto Canada

Based on the analysis theory of random energy of train derailment, an analysis theory of random energy of train derailment in wind is suggested. Two methods are proposed -the time domain method and the frequency domain method of analysis theory of random energy of train derailment in wind. The curves of σ pw -v under various wind speeds are obtained through the computation. The original curve of σ p -v is expanded, which turns the analysis theory of random energy of train derailment into the all-weather theory. Train derailment condition has been established under wind action. The first and second criterions of train derailment have been proposed in light of wind action. The analysis of train derailment cases at home or abroad is made, in- cluding the first analysis of Xinjiang train derailment case encountered 13.level of gale, which explained the inevitability of train derailment. The analysis theory of random energy of train derailment in wind shows its validity and accuracy. The input energy σ pw of the transverse vibration of train-track(bridge)-wind system is linked to train speed. With the establishment of the analysis theory of random energy of train derailment in wind, It is likely to initiate an all-weather speed limit map for a train or any high-speed train.

关键词： train derailment analysis theory of random energy of train derailment analysis theory of random energy of train de- railment in wind train derailment condition in wind the criterion of train derailment in wind train derailment case

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DYNAMIC BEHAVIORS OF CONDUCTIVE CIRCULAR PLATE IN TIME-VARYING MAGNETIC FIELDS

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Acta Mechanica Solida Sinica 2010年第1期23卷 66-76页

作者： Yuanwen Gao1 Bang Xu(Key Laboratory of mechanics on Western Disaster and Environment,College of civil engineering and mechanics,lanzhou University,lanzhou 73.000,china) Key Laboratory of mechanics on Western Disaster and Environment College of Civil Engineering and Mechanics Lanzhou University Lanzhou China

In this study, we proposed an analytical solution for eddy currents as well as electromagnetic forces of a conductive circular plate in a time varying magnetic field. Specifically, an analytical series solution for eddy currents in a circular plate subjected to an axisymmetrie time varying magnetic field has been proposed based on the T-method that has been widely used in the eddy current analysis of conductive and superconductive structures. Accordingly, the dynamic response, the dynamic instability and the magnetic damping of a circular plate in a transverse transient magnetic field as well as a stationary in-plane magnetic field have also been obtained. The analytical series solution proposed in this work as well as the subsequent numerical analysis not only confirmed the emergence of dynamic instability of a circular plate in a strong transverse magnetic field, but also demonstrated the existence of magneto-damping of a circular conductive plate in an in-plane magnetic field. The method developed in this paper provides a potential new possible way by which the analysis of the electromagnetic coupling problems of conductive structures can be simplified.

关键词： dynamic response circular conductive plate series solution for eddy current Bessel function

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Analysis on cohesive crack opening displacement considering the strain softening effect

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Science china(Physics,mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1, XU Shilang2 & ZHAO Xiqiang3.1. mechanics Department, Shandong University of Technology, Zibo 255049, china 2. civil {3. Department, Dalian University of Technology, Dalian 116024, china 3. Mathematics Department, Ocean University of china, Qingdao 266071, china mechanics Department Shandong University of Technology Zibo China civil engineering Department Dalian University of Technology Dalian China Mathematics Department Ocean University of China Qingdao China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

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Allocation of power generating and shipping of Hanjiang upstream cascade

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Progress in Natural Science:Materials International 2005年第8期15卷 733-741页

作者： LIU Junping1* and CHANG Mingqi 2,3.1. school of civil engineering and Architecture, Zhejiang University of Technology, Hangzhou 3.0014,{3. 2. Institute of Water Resources & Hydroelectric engineering, Xi'an University of Technology, Xi'an 710048,{3. 3. Shanxi Institute of Water Resources, Taiyuan 03.001,{3.) school of civil engineering and Architecture Zhejiang University of Technology Hangzhou 310014 China Institute of Water Resources and Hydroelectric engineering Xi'an University of Technology Xi'an 710048 China Shanxi Institute of Water Resources Taiyuan 030001 China

The optimal model and simulating model of the Hanjiang cascade reservoirs operation with one day as its calculating period are established to coordinate the contradictions between power generating and shipping. The optimal model is solved by progressive optimality algorithm method adopting the theory of large system decomposing and coordinating. By analyzing the water allocation results obtained from six schemes, which are two cascades, four cascades and seven cascades joint operation considering shipping or not, the contradiction degree between power generating and shipping is investigated and some joint operation schemes are proposed.

关键词： cascade power generating contradiction shipping optimal operation.

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A theoretical model of collision between soft-spheres with Hertz elastic loading and nonlinear plastic unloading

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Theoretical & Applied mechanics Letters 2011年第4期1卷 34-39页

作者： Youhe Zhou 1,2,a) 1) Key Laboratory of mechanics on Disaster and Environment in Western china,the Ministry of Education of china 2)Department of mechanics and engineering Science,College of civil engineering and mechanics,lanzhou University,lanzhou 73.000,china Key Laboratory of mechanics on Disaster and Environment in Western china the Ministry of Education of China China Department of mechanics and engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou 730000 China

This paper presents a theoretical model on the normal(head-on) collision between soft-spheres on the basis of elastic loading of the Hertz contact for compression process and a nonlinear plastic unloading for restitution one,in which the parameters all are determined in terms of the material and geometric ones of the spheres,and the behaviors of perfect elastic,inelastic,and perfect plastic collisions appeared in the classical mechanics are fully described once a value of coefficient of restitution is specified in the region of 0 ≤ ε ≤ *** an empirical formula of the coefficient of restitution dependent on the impact velocity is suggested to fit the existing experimental measurements by means of the least square method,the predictions of the dependency and the collision duration are in well quantitative agreement with their experimental *** is found that the measurable quantities are dependent on both the impact velocity and the parameters of *** this model,finally,an approach to determine the spring coefficient in the linear viscoelastic model of the collision is also *** results obtained here will be significantly beneficial for the applications where a collision model is requested in the simulations of relevant grain flows and impact dynamics etc..

关键词： normal collision of soft-spheres theoretical model residual displacement restitution coefficient collision duration

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