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Macro-micromechanical approaches for non-coaxiality of coarse grained soils

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中国科学：技术科学英文版 2011年第S1期54卷 147-153页

作者： QIAN JianGu 1,2,HUANG MaoSong 1,2 & SUN HaiZhong 1,2 1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,shanghai 200092,china 2 department of Geotechnical Engineering,tongji university,shanghai 200092,china 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai 200092 China2. Department of Geotechnical Engineering Tongji University Shanghai 200092 China

For coarse grained soils,their principal stress directions may change when the water level of embankment dam varies *** this loading case,the principal directions of stress and strain rate will become *** an effort to model non-coaxial behavior,a modified three-dimensional non-coaxial model is developed in the context of vertex yield(tangent plasticity) *** Element Method(PFC) incorporating user-defined interparticle contact models is also employed to gain an insight into microscopic mechanism of *** analysis focuses on non-coaxial behaviors under simple shear *** has been shown that the proposed non-coaxial model gives good predictions for non-coaxiality with reference to microscopic observations while the classical coaxial model fails to simulate the non-coaxial *** general,non-coaxiality as a result of the rotation of principal stress,is large at a small shear strain,and inclined to become negligible with increasing shear *** coarse grained soils,their non-coaxiality tends to largely depend on the initial normal pressure,where a larger degree of non-coaxiality can be observed at a higher pressure.

关键词： coarse grained soils non-coaxiality particle flow code simple shear

Nonlinear constitutive law for ferroelectric/ferroelastic material and its finite element realization

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Science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 70-86页

作者： LI YaoChen department of Aerospace Engineering and Applied Mechanics,tongji university,shanghai 200092,china department of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092 China

The hysteresis phenomena of ferroelectric/ferroelastic material in polarization procedure are investigated. Some assumptions are presented based on the published experimental data. The electrical yielding criterion, mechanical yielding criterion and isotropic hardening model are established. The flow theory in incremental forms in polarization procedure is presented. The nonlinear constitutive law for electrical-mechanical coupling is proposed phenomenologically. Finally, the nonlinear constitutive law expressed in a form of matrices and vectors, which is immediately associated with finite element analysis, is formulated. In the example problem of a rectangular specimen subjected to a uniaxial electric field, the procedure from virgin state to fully polarized state is simulated. Afterward, a uniaxial compressive loading is applied to depolarizing the specimen. Results are in agreement with the experimental data.

关键词： ferroelectric/ferroelastic material constitutive law nonlinear finite element method.

Analytical solution for wave-induced response of isotropic poro-elastic seabed

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Science china(Technological Sciences) 2010年第10期53卷 2619-2629页

作者： ZHANG YongLi & LI Jie department of Building Engineering, tongji university, shanghai 200092, china 1. department of Building Engineering Tongji University Shanghai 200092 China

By use of separation of variables,the governing equations describing the Biot consolidation model is firstly transformed into a complex coefficient linear homogeneous ordinary differential equation,and the general solution of the horizontal displacement of seabed is constructed by employing a complex wave number,thus,all the explicit analytical solutions of the Biot consolidation model are determined. By comparing with the experimental results and analytical solution of Yamamoto etc. and the analytical solution of Hsu and Jeng,the validity and superiority of the suggested solution are verified. After investigating the influence of seabed depth on the wave-induced response of isotropic poro-elastic seabed based on the present theory,it can be concluded that the influence depth of wave-induced hydrodynamic pressure in the seabed is equal to the wave length.

关键词： linear wave dynamic water pressure seabed analytical solution Biot consolidation model

Model test of the tunnel subjected to high water pressure in Jinping Second Cascade Hydropower Station,china

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Science china(Technological Sciences) 2011年第S1期54卷 192-198页

作者： WANG JianXiu 1,2,FENG Bo 2,HU LiSheng 2,TIAN PuZhuo 2,SUI DongChang 2,TANG YiQun 1,2 &YANG Ping 1,2 1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,shanghai 200092,china 2 department of Geotechnical Engineering,tongji university,shanghai 200092,china 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai 200092 China2. Department of Geotechnical Engineering Tongji University Shanghai 200092 China

In the area with high groundwater pressure,grout curtain is often adopted to reduce the water pressure on tunnel lining.A series of model tests for the diversion tunnel of the Jinping Second Cascade Hydropower Station,china,is designed to study the effect of grout *** impact of the thickness of grout curtain,permeability of grout curtain,internal water pressure and drainage inflow on the distribution of water pressure are *** results indicates that under un-drained condition,water pressure is equal to hydrostatic one no matter grout curtain is selected or not,water pressure under drained condition is far less than that of un-drained condition,drainage in tunnel can reduce tunnel water pressure *** same inflow,both increasing of thickness and decrease of hydraulic conductivity of grout curtain can reduce water pressure *** the same water pressure,the smaller inflow of grout curtain,the less volume of water to be *** impact of hydraulic conductivity of grout curtain is more obvious than that of *** increasing of internal water pressure,the water pressure of grout curtain increases too,and the water pressure increases nearly *** proposed thickness of grout curtain for the diversion tunnels is 16 m.

关键词： tunnel grout curtain water pressure model test

Error matching detection and robust estimation adjustment approach for map conflation

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Science china(Technological Sciences) 2008年第S1期51卷 48-61页

作者： TONG XiaoHua & DENG SuSu department of Surveying and Geo-informatics,tongji university,shanghai 200092,china tongji Univ Dept Surveying & Geoinfromat Shanghai 200092 Peoples R China

The conflation of geographic datasets is one of the key technologies in the realm of spatial data capture and integration in geographic information system (GIS). Map conflation is a complex process of matching and merging spatial data. Due to various reasons such as errors in original data related to map data discrepancies,a great amount of uncertainties exists during the process and this will result in errors in featuring matching,especially point feature. Thus,it is vital to develop the method to detect the errors in feature matching and further the conflation results will not be affected. In this paper,error matching detection and robust estimation adjustment methods are proposed for map conflation. The characteristics of errors in feature matching are first analyzed,then a new approach for map conflation based on the least-squares adjustment is presented,and a robust estimation adjustment method is further proposed to detect and process matching errors. The results of the map conflation test show that the proposed method not only determines the errors in feature matching,but also obtains the optimal merging results in map conflation.

关键词： map conflation robust estimation error feature matching uncertainty

GLOBALLY CONVERGENT INEXACT GENERALIZED NEWTON METHODS WITH DECREASING NORM OF THE GRADIENT

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Journal of Computational mathematics 2002年第3期20卷 289-300页

作者： Ding-guo Pu (department of mathematics, tongji university, shanghai 200331, china) department of mathematics Tongji University 上海 200331

Presents information on a study which proposed a type of globally convergent inexact generalized Newton methods to solve unconstrained optimization problems. Theorems on inexact generalized Newton algorithm with decre... 详细信息

关键词： nonsmooth optimization inexact Newton method generalized Newton method global convergence superlinear rate

A MULTI-GRID ALGORITHM FOR STOKES PROBLEM

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Journal of Computational mathematics 1995年第4期13卷 291-305页

作者： Z. Huang(department of Applied mathematics, tongji university, shanghai, china) tongji UNIV DEPT MATH APPLSHANGHAI 200092PEOPLES R CHINA

In this paper we describe a multi-grid algorithm for the penalty procedure of Stokes problem. It is proved that the convergence rate df the algorithm is bounded away from 1 independently of the meshsize. For convenien... 详细信息

关键词： Math Grid ED EH Bank

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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Science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2 1. department of Civil Engineering,shanghai university,shanghai 200072,china 2. School of Transportation Engineering,tongji university,shanghai 200092,china 1. department of Civil Engineering Shanghai University Shanghai 200072 China 2. School of Transportation Engineering Tongji University Shanghai 200092 China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

ON THE LAPLACIAN SPECTRAL RADII OF TREES WITH NEARLY PERFECT MATCHINGS

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Journal of Systems Science & Complexity 2009年第3期22卷 533-540页

作者： Li ZHANG Jiayu SHAO department of Applied mathematics Shanghai Finance University Shanghai 201209 China. department of mathematics Tongji University Shanghai 200092 China.

Let ：T2k＋1 be the set of trees on 2k＋ 1 vertices with nearly perfect matchings, and let S2k＋2 be the set of trees on 2k ＋ 2 vertices with perfect matchings. The largest Laplacian spectral radii of trees in ：T2k＋l and S2k＋2 and the corresponding trees were given by Guo （2003）. In this paper, the authors determine the second to the sixth largest Laplacian spectral radii among all trees in T2k＋1 and give the corresponding trees.

关键词： Tree Laplacian eigenvalue nearly perfect matching perfect matching.