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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 445-454页

作者： Li Yuchun Shen Chao Liu Wei Li Dong department of hydraulic Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on columns.The parametric vibration equation is established for the test model using the finite-element method.The auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent method.The effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test model.Compared with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental ones.For a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric resonance.Combined with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

关键词： auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd Bridge

Dynamic Properties of Concrete under Severe Environmental Condition

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Journal of Wuhan University of Technology(Materials Science) 2010年第5期25卷 877-882页

作者：闫东明 department of hydraulic and Environmental Engineering Zhengzhou University department of Civil and hydraulic Engineering Dalian University of Technology

Exposure to environmental conditions can significantly influence the mechanical behavior of concrete structures in civil engineering. In this study, the effect of environmental factors, such as moisture and temperature, on the strain-rate sensitivity of concrete mixtures was systematically investigated. The strain rate varied from 10^-5s^-1 to 10^-2s^-1. From the investigation it was concluded that moisture content had a significant influence on the strain-rate sensitivity of concrete. With regard to concrete with low moisture content, temperature had little influence on the rate-dependent behavior; while for fully saturated specimens, a significant influence was observed. These phenomena were attributed to the meso-scale bonding properties of the concrete matrix. Equations were derived to characterize the ultimate strength increment of concrete with strain rate under different environmental conditions. An explanation to the dynamic failure mechanisms of concrete based on the experimental findings was proposed.

关键词： concrete strain rate moisture content temperature failure mechanism

Fractal Characteristics of Round Jets in Steady Crossflow

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Communications in Nonlinear Science and Numerical Simulation 1998年第3期3卷 183-186页

作者： Yuhang LI Chaoquan CHEN and Chunbo JIANG(hydraulic department, Tsinghua University, Beijing 100084, China) hydraulic department Tsinghua University Beijing 100084 China

The fractal dimensions of turbulent round jets in steady crossflow has beenanalyzed by using planar laser-induced fluorescence (PLIF) method. The relation betweenthe fractal dimension and the momentum ratio, the variation of the fractal dimension withthe elevation of jet and the dilution have been investigated. The comparison of the fractalcharacteristics between the multiple jets and the signal jet has been carried out.

关键词： steady crossflow turbulent jet measurement of fractal dimension

Numerical Simulation of Nonlinear Radiation Water Surface Wave Caused by Large-Amplitude Oscillation of A Cylinder

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Communications in Nonlinear Science and Numerical Simulation 1999年第1期4卷 24-28页

作者： Wuzhou HE (department of hydraulic Engineering, Tsinghua University, Beijing 100084, China) department of hydraulic Engineering Tsinghua University Beijing 100084 China

The BEM combined with the time-stepping scheme is employed in the nonlinear numerical simulation of the development process of radiation wave profile and hydrodynamic force caused by large amplitude oscillating cylinder. To ensure stability and accuracy of the simulation, special consideration is paid on a series of difficulties in numerical modeling, such as the compatibility of free surface and body surface conditions at the intersection point and the open boundary condition problem. Numerical calculation is carried out for some study cases of different shaped cylinders undergoing large amplitude oscillating motions with distinct modes, the results show. some nonlinear phenomena and indicate the feasibility of the numerical approach.

关键词： 2-D water surface wave boundary element method time-stepping scheme

Interaction Mechanisms between Natural Debris Flow and Rigid Barrier Deflectors:A New Perspective for Rational Design and Optimal Arrangement

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1679-1699页

作者： Yu Huang Beilei Liu Dianlei Feng Hao Shi department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai200092China department of hydraulic Engineering College of Civil EngineeringTongji UniversityShanghai200092China

Rigid barrier deflectors can effectively prevent overspilling landslides,and can satisfy disaster prevention requirements.However,the mechanisms of interaction between natural granular flow and rigid barrier deflectors require further investigation.To date,few studies have investigated the impact of deflectors on controlling viscous debris flows for geological disaster prevention.To investigate the effect of rigid barrier deflectors on impact mechanisms,a numerical model using the smoothed particle hydrodynamics(SPH)method with the Herschel–Bulkley model is proposed to simulate the interaction between natural viscous flow and single/dual barriers with and without deflectors.This model was validated using laboratory flume test data from the literature.Then,the model was used to investigate the influence of the deflector angle and multi-barrier arrangements.The optimal configuration of multi-barriers was analyzed with consideration to the barrier height and distance between the barriers,because these metrics have a significant impact on the viscous flow pile-up,run-up,and overflow mechanisms.The investigation considered the energy dissipation process,retention efficiency,and dead-zone formation.Compared with bare barriers with similar geometric characteristics and spatial distribution,rigid barriers with deflectors exhibit superior effectiveness in preventing the overflow and overspilling of viscous debris flow.Recommendations for the rational design of deflectors and the optimal arrangement of multi-barriers are provided to mitigate geological disasters.

关键词： Rigid barrier deflectors deflector angle single-barrier dual-barrier arrangements viscous debris flow over-spilling delta-plus-SPH

3D mathematical model for suspended load transport by turbulent flows and its applications

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Science China(Technological Sciences) 2004年第2期47卷 237-256页

作者： LU Yongjun1,DOU Guoren1,HAN Longxi2,SHAO Xuejun3 & YANG Xianghua1,3 1.Nanjing hydraulic Research Institute,Nanjing 210029,China 2.College of Environmental Engineering of Hohai University,Nanjing 210098,China 3.department of hydraulic Engineering,Tsinghua University,Beijing 100084,China Nanjing hydraulic Research Institute Nanjing China College of Environmental Engineering of Hohai University Nanjing China department of hydraulic Engineering Tsinghua University Beijing China

This paper presents a 3D mathematical model for suspended load transport in turbulent flows. Based on Dous stochastic theory of turbulent flow, numerical schemes of Reynolds stresses for anisotropic turbulent flows were obtained. A refined wall function was employed to treat solid wall boundaries. The equations for 2D suspended load motion and sorting of bed material have been expanded into 3D cases. Numerical results are validated by the measured data of the Gezhouba Project, and proved to be in good agreement with the experimental. The present method has been employed to simulate sediment erosion and deposition in the dam area of Three Gorges Project, and for the operation of the project, siltation process and deposition pattern in the near-dam area of the reservoir, size distribution of the deposits and bed material, and flow fields and sediment concentration fields at different time and elevations are predicted. The predicted results are close to the experimental observations in physical model studies. Thus, a new method is established for 3D simulation of sediment motion in dam areas of multi-purpose water projects.

关键词： turbulent flows, Dou's stochastic theory, nonuniform suspended load, riverbed erosion and deposition, 3D mathematical model, Three Gorges Project.

Research on analysis method for temperature control information of high arch dam construction

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Science China(Technological Sciences) 2011年第S1期54卷 40-46页

作者： ZHONG DengHua,ZHAO ChenSheng & REN BingYu department of hydraulic and Hydroelectric Engineering,School of Civil Engineering,Tianjin University,Tianjin 300072,China department of hydraulic and Hydroelectric Engineering School of Civil Engineering Tianjin University Tianjin China

Temperature control,which is directly responsible for the project quality and progress,plays an important role in high arch dam construction.How to discover the rules from a large amount of temperature control information collected in order to guide the adjustment of temperature control measures to prevent cracks on site is the key scientific problem.In this paper,a mathematic logical model was built firstly by means of a coupling analysis of temperature control system decomposition and coordination for high arch dam.Then,an analysis method for temperature control information was presented based on data mining technology.Furthermore,the data warehouse of temperature control was designed,and the artificial neural network forecasting model for the highest temperature of concrete was also developed.Finally,these methods were applied to a practical project. The result showed that the efficiency and precision of temperature control was improved,and rationality and scientificity of management and decision-making were strengthened.All of these researches provided an advanced analysis method for temperature control in the high arch dam construction process.

关键词： high arch dam construction temperature control information data mining data warehouse neural network model

AN ENHANCED ELEMENT-FREE GALERKIN METHOD FOR DYNAMIC RESPONSE OF POROELASTIC SEABED

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Journal of Hydrodynamics 2009年第3期21卷 429-435页

作者： HUA Lei-na YU Xi-ping State Key Laboratory of Hydroscience and Engineering Department of Hydraulic Engineering Tsinghua University Beijing 100084 China

This study presents an effective numerical model for the dynamic response of poroelastic seabed under wave action with enhanced performance. The spatial discretization is based on the Element-Free Galerkin （EFG） method and the time integration based on the GN11 scheme. A stability strategy that adopts a smaller number of nodes for the pore water pressure compared with those for the displacements of the soil skeleton is suggested to resolve the similar difficulty as encountered in the finite element method for a problem with mixed formulation when the pore water is incompressible and the soil skeleton impervious. The accuracy of the numerical model is verified through applying it to a typical case with critical permeability. Good agreement between computational and analytical solutions is obtained.

关键词： poroelastic seabed dynamic response Element-Free Galerkin （EFG） method mixed formulation

A COUPLED 1-D AND 2-D CHANNEL NETWORK MATHEMATICAL MODEL USED FOR FLOW CALCULATIONS IN THE MIDDLE REACHES OF THE YANGTZE RIVER

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Journal of Hydrodynamics 2011年第4期23卷 521-526页

作者： HAN Dong FANG Hong-wei BAIJing HE Guo-jian department of hydraulic Engineering and State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

A coupled one-dimensional （1-D） and two-dimensional （2-D） channel network mathematical model is proposed for flow calculations at nodes in a channel network system in this article. For the 1-D model, the finite difference method is used to discretize the Saint-Venant equations in all channels of a looped network. The Alternating Direction Implicit （ADI） method is adopted for the 2-D model at the nodes. In the coupled model, the 1-D model provides a good approximation with small computational effort, while the 2-D model is applied for complex topography to achieve a high accuracy. An Artificial Neural Network （ANN.） method is used for the data exchange and the connectivity between the 1-D and 2-D models. The coupled model is applied to the Jingjiang-Dongting Lake region, to simulate the tremendous looped channel network system, and the results are compared with field data. The good agreement shows that the coupled hydraulic model is more effective than the conventional 1-D model.

关键词： Coupled 1-D and 2-D model looped channel network system Alternating Driection Implicit （ADI） Jingjiang-Dongting Lake region

Dynamic Analysis for Structures Isolated with Dampers

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China Ocean Engineering 1996年第3期11卷 269-280页

作者： Gu Peiying and Gao Ming M. Sc, Engineer, Material and Structure department, Nanjing hydraulic Research Institute, Nanjing 210024 Professor, Material and Structure department, Nanjing hydraulic Research Institute, Nanjing 210024 Material and Structure department Nanjing Hydraulic Research Institute Nanjing 210024

In this paper, mathematical models and dynamic analyses for both SDOF and MDOF structures isolated with dampers are established and performed, and a comprehensive computation method is provided. The shock absorbing effect is illustrated through an example of a two DOF damper-isolated system excited by sinusoidal waves and actual ground acceleration input recorded in earthquakes. It is shown that most of the responses of the structure with dampers reduce greatly near the resonant zone, but acceleration is enlarged in the lower or higher frequency zone; among various parameters, the influence of frictional coefficient n is the most significant, that of damping ratio of the dampers , is the second, and that of stiffness coefficient of the dampers k, is the slightest.

关键词： shock absorbing structure isolated with dampers shock absorbing effect dynamic analysis parametric analysis