交通运输工程学报

Wheelset climb derailment criteria for evaluation of railway vehicle running safety

CENG Jing, GUAN Qing-hua

Abstract: In order to understand the mechanism and the main factors that cause vehicle climb derailment, the forces exerted on wheelset in 3D space were analyzed, the general ratio formulae of wheel/rail lateral force to vertical force were derived.It was assumed that wheelset reached the critical state of derailment when flange contact occurred, full friction sliding between wheel and rail appeared, 2D evaluation derailment criterion of wheelset without considering wheelset yaw angle was derived, and 3D criterion with taking into account wheelset yaw angle and the effect of wheel/rail creepages was given.The concept of wheelset derailment coefficient was defined, and the combination of wheelset derailment coefficient and wheel load reduction rate was utilized to evaluate derailment.Simulation result shows that 2D criterion is more conservative for derailment evaluation compared with 3D criterion; smaller and negative yaw angles can mitigate derailment possibility, the critical derailment curve of 3D criterion tends to the situation of 2D criterion at larger wheelset yaw angles; the reduction of friction coefficient and the increase of flange angle are advantageous for preventing derailment.More>

2007, 7(6): 1-5.

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Comparison of dynamic high-speed curving properties for wheel profiles

ZHANG Jian, SUN Li-ping

Abstract: In order to effectively choose wheel profiles, the high-speed curving characteristics of wheelset were obtained by vehicle-track coupling dynamics simulation, wheel/rail contact geometry property and creeping ratio were calculated with wheelset curving dynamic parameters, wheel/rail non-Hertzian rolling contact was analyzed by using Contact program, and the high-speed curving matching characteristics of LMa, S1002 and XP55 wheel profiles were studied.Analysis result shows that the curves of wheelset dynamic parameters for LMa and XP55 profiles are smooth, S1002 profile exhibits large amplitude oscillation, and hunting occurs; wheel/rail contact point of S1002 profile jumps 11 mm while wheelset laterally displaces from 3.0 to 3.5 mm, just in the transitional arc of rail profile from R300 to R80 mm; the contact patch of S1002 profile generally slides, the contact stress of LMa profile is lowest, and the contact stress of XP55 profile is highest.So S1002 profile incompatibly matches Chinese 60 kg·m^-1 rail, the matching effect of XP55 profile is better, and the matching effect of LMa profile is best.More>

2007, 7(6): 6-11.

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Brake performances of 20000 ton connected train

WEI Wei

Abstract: In order to decrease the longitudinal impact of loaded train, and improve the synchronization property of its brake system, a pneumatic brake simulation system was put forward based on airflow theory, the momentary airflow state of train brake system was calculated to get its dynamic characteristics, the performances of service brake and emergency brake for 20000 ton loaded train were predicted, and the propagation performances of brake waves were analyzed.Simulation result shows that the maximum brake time delay of train with 2 sub-trains decreases by 50%, if locomotives are added to the ends of sub-trains, the delay decreases by 75%, and the delay of train with 4 sub-trains reduces by 75% too; emergency brake wave propagates forward and backward from locomotive at the same speed, service brake wave propagates forward at a slower speed than backward.Obviously, connected train has better brake synchronization property.More>

2007, 7(6): 12-16.

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Dynamic stress calculation method of locomotive and vehicle carbody structures

MOU Bing-rong, ZHANG Wei-hua, XIAO Shou-ne, JIN Ding-chang

Abstract: In order to improve the fatigue lives of locomotive and vehicle and optimize their carbody structures, a synthetical computation method of dynamic stress was proposed based on multi-body system (MBS) simulation model and finite element method, and the dynamic stresses of locomotive and vehicle carbody structures were calculated.Taking carbody as core, MBS simulation model of locomotive was established, and its simulation analysis was performed to obtain the load time histories of crucial positions.Finite element method (FEM) and quasi-static stress analysis method were used to calculate stress influence coefficients (SIC).Carbody dynamic stress history was produced by multiplying each stochastic load-time history by the SIC resulted from corresponding unit load, and the dynamic stress test result of carbody structure was compared with the simulation result of rigid and flexible carbodies.Comparison result shows that their errors are 2.462% and 7.258% respectively, which indicates that the computational precision of the method is high.More>

2007, 7(6): 17-20.

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Elastic finite element analysis model of coupling friction heat for wheel/rail

WU Lei, WEN Ze-feng, JIN Xue-song

Abstract: Based on Galerkin variation principle, an elastic finite element analysis model of coupling friction heat for wheel/rail was put forward, and the relations between wheel/rail friction heat and rail expanded displacement in touched area, wheel/rail frictional temperature, contact strain and stress.In the model, inertia term and material damping were ignored, temperature field and displacement field were synchronously solved by using coupling equations.Analysis result shows that coupling simulation values are identical with uncoupling computation values for temperature field and displacement field, the sliding displacement direction of rail surface contact node is identical with wheel sliding direction, and the vertical displacement is negative earlier then positive later; the temperature of rail surface contact node rises quickly in contact area, but the durative time of high temperature is very short, rail surface node experiences press strain early and pull strain later in sliding direction, experiences pull strain in vertical direction, the press stress in sliding direction is higher than in vertical direction, and the strain signs in the front and back of contact note are opposite; the vertical high strains are mostly distributed in the tail of half axle of contact area, and the maximum shear strain and stress appear under contact surface.More>

2007, 7(6): 21-27.

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Effect of hard spot on dynamic response of railway sleeper

XIAO Xin-biao, JIN Xue-song, WEN Ze-feng

Abstract: a vehicle-track coupling dynamics model was established based on Timoshenko beam model, vehicle was modeled as a 35 DOF multi-body system, track was modeled as a 3-layer discrete elastic support model, and the motion properties of vehicle/track coupling system were solved by using new-explicit-integration method.The effect of rail vertical, torsional and lateral motions on wheel/rail rolling contact geometry relationship was taken into account, wheel/rail normal forces were calculated by using Hertzian contact theory, and wheel/rail creep forces in rolling contact were computed by using Shen nonlinear creep theory.The support hard spots of sleepers with non-uniform support heights along track were simulated, and the effect of their number and heights on the model was analyzed by using moving rail-supported model.Numerical simulation result indicates that the number of hard spots greatly affects the dynamic responses of track system rather than vehicle system, especially railway sleeper.As the height is 1.0 mm, the maximum rail/sleeper force and tension are almost 2 and 10 times larger than normal values respectively.However, the dynamic responses of vehicle-track coupling system aren't sensitive to the number of hard spots.More>

2007, 7(6): 28-35.

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Pulse control measure methods of internal resistance for battery in electric vehicle

ZHANG Wei-gang, ZHANG Wei-feng, REN Wei-jun, BIAN Yao-zhang

Abstract: In order to estimate the health state of battery and calculate the running distance of electric vehicle (EV), two pulse control measure methods were put forward to for the online test of internal resistance for battery.Measure circuit and battery were insulated by using optical coupling set and transformer, a series of pluses were put out by microcomputer unit (MCU), constant current signal was generated by battery controlled by optical coupling set, voltage signal caused by current signal in the internal resistance was sent to MCU through transformer, and MCU could calculate the internal resistance according to the phase difference between voltage and current (method 1) or voltage difference (method 2).Computation result shows that the errors of internal resistance for a 12V lead-acid battery are about 13% and 11% respectively calculated by using method 1 and method 2, the errors are less, so two pulse control methods are feasible.More>

2007, 7(6): 36-40.

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Hybrid prediction control model of ship's track

ZHANG Gui-chen, REN Guang

Abstract: In order to improve the control quality of ship's track, a hybrid prediction control model was established.The uncertain variables of ship's dynamics were estimated by using grey predicting technique, while back propagation adaptive neural network with multilayer perceptrons was used to analyze the trend of control error development for ship's track based on studying ship's response errors, the optimal combination and optimal weight coefficients of the model were ascertained according to the difference of the above two results, so that the optimum control strategy was found.Simulation result shows that the oscillation of ship PID control system will occurs when one index value of demurrage, turning ability and following ability is more than 1, while the model enables ship's track errors to converge quickly with less rudder movement, so that ship's planning track accords with ship's real track, hereby, the robustness, rapidness and stability of the model are higher.More>

2007, 7(6): 41-45.

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Structure design of long-life pavement

WANG Xuan-cang, HOU Rong-guo

Abstract: In order to increase the actual service life of pavement, the definition and design requirement of long-life pavement were studied, a long-life pavement structure based on PCC(cement concrete pavement)+AC(asphalt concrete pavement) pavement was suggested.With finite element analysis software and elastic layer system theory of pavement, the superiority of 3.0 m×4.0 m slab division for PCC was analyzed, and the load stress and temperature stress of long-life pavement structure were calculated.Analysis result shows that the temperature curling stress and comprehensive stress at concrete slab bottom are reduced by about 20% and 10% respectively, the theoretical life of suggested pavement structure reaches 46 a, and it satisfies design requirement.More>

2007, 7(6): 46-49.

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Prediction methods of remaining life for composite pavement of airport

ZHOU Zheng-feng, LING Jian-ming, YUAN Jie

Abstract: Based on elastic layer system theory design method of Federal Aviation Administration(LEDFAA), airport pavement design method of China(APDMC) and pavement condition index(PCI) regression model, three prediction methods of remaining life for composite pavement of airport were established, the prediction results and applicabilities of three methods were compared.Analysis result indicates that the remaining lives calculated by three methods are approximate, the maximum deviation is 3.2 a, the minimum deviation is 0.1 a, and the deviation is mainly induced by different control indices of three models.Remaining life is most sensitive to subgrade modulus and concrete flexural-tensile strength for the methods based on LEDFAA and APDMC respectively, PCI regression model is recommended on the condition of having sufficient historical data of pavement performance.More>

2007, 7(6): 50-54.

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Vehicle dynamic load property resulted from road random roughness

LU: Peng-min, YOU Jin-min, HE Li-mei

Abstract: Road random roughness was simulated by using inverse fast Fourier transform(IFFT) in time domain, a half-vehicle dynamics model was established, the effects of road grade, vehicle velocity, loading capacity and vehicle parameters on vehicle dynamic load were studied by Runge-Kutta method, and the rules of vehicle dynamic load caused by road roughness were studied.Simulation result indicates that vehicle dynamic load increases obviously with the intensification of road roughness; vehicle dynamic load and the dynamic load coefficient increase with the increase of vehicle speed, their peak values appear nearby inherent frequency; dynamic load coefficient decreases and vehicle dynamic load increases with the increase of loading capacity, so overload phenomena is strictly limited; increasing tire stiffness and decreasing suspension damping can lead to the increase of vehicle dynamic load and dynamic load coefficient, so the use of high pressure tire should be limited and the selection of suspension damping should be reasonable.More>

2007, 7(6): 55-58.

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Fractal description method of asphalt mixture rut resistance

HUANG Bao-tao, LIANG Yi, CUI E, HUANG Xiao-ming, TIAN Wei-ping, LI Jia-chun

Abstract: In order to accurately simulate rut resistance capability of asphalt mixture, its microstructure was analyzed by using fractal theory, the influences of different fractal dimensions for coarse and fine aggregates on the capability were studied, the fractal values were calculated according to gradation fractal dimension formulas, and the rutting test of asphalt mixture and the electronic scanning of the microstructure were carried out.Analysis result shows that 4.75 mm passing rate is the dividing point of aggregate scales, aggregate fractal dimension has consistent pertinence with the capability, the bigger fractal dimension value is, the finer the capability is; gradation difference, pavement performance and the relationship between pavement microstructure and macroscopical performance can be quantitatively analyzed by using aggregate gradation design method.More>

2007, 7(6): 59-63.

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Zoning scheme of climatic influence for asphalt pavement in China

MIAO Ying-hao, WANG Bing-gang

Abstract: To understand the effect of climatic conditions on asphalt pavement in China, the weather data of 739 weather stations in 1971~2000 were analyzed, average annual accumulated temperature above 20℃, average annual accumulated rain-temperature index, average annual precipitation-freezing index and extremely low air temperature were taken as zoning indices, average daily solar radiation was taken as describing index, the spatial distributions of the indices were analyzed by using Kriging and Cokriging method, and with the methods of cluster analysis, indices division and maps overlay, a climatic zoning scheme was proposed which included 8 first level regions and 39 second level regions. Low temperature and precipitation in low temperature term are main factors impacting asphalt pavement in Northern China and Qinghai-Tibet Plateau, high temperature and precipitation are main aspects in Southern China, however, every factor should be comprehensively considered in Central China because the effect of every factor is relatively balanceable.More>

2007, 7(6): 64-69.

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Numerical simulation of mechanical behavior for pile-column supported subgrade over soft ground

JIANG Xin, LING Jian-ming

Abstract: Based on FLAC(fast Lagrangian analysis of continua) of 2D explicit finite difference method, a numerical simulation model was established to investigate the mechanical behavior of pile-column-supported subgrade(PCSS) over soft ground.Pile, column and reinforcement geogrid were modeled by using pile elements and cable elements respectively, the surface settlement, ground lateral displacement, pore water pressure, stability of the subgrade were studied, the internal force distributions of pile, column and reinforcement geogrid were analyzed, the characteristics of PCSS and traditional subgrade were compared, and the influences of design parameters for pile, column, embankment, reinforcement geogrid and foundation on subgrade settlement and foundation lateral deformation were studied.Analysis result shows that compared with traditional subgrade, the ratios of the maximum surface settlement, differential settlement of subgrade, the maximum lateral deformation of foundation are 1.48%, 1.40% and 0.88% respectively, so the mechanical behavior of the subgrade is better.More>

2007, 7(6): 70-75.

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Analysis of deformation and strength parameters for cohesive clay

JIANG Jian-ping, LUO Guo-yu, GAO Guang-yun

Abstract: In order to understand the engineering properties of cohesive clay in the foundation of Sutong highway large bridge in the lower reaches of Yangtze River, the deformation and strength parameters were studied based on a large number of geotechnical tests and regression analysis method.Study result shows that the variation coefficients of deformation and strength parameters for cohesive clay are larger than those of physical parameters; there is good exponential correlativity between compression module and three physical parameters that are natural pore-solid ratio, natural water content and dry density, the correlativity coefficients are more than 0.87;there is linear correlativity between compression coefficient and three physical parameters, the correlativity coefficients are more than 0.91;there is better exponential correlativity between cohesion and three physical parameters, their correlativity coefficients are more than 0.84;while the correlativity between internal friction angle and three physical parameters is bad, their linear correlativity coefficients are less than 0.41.More>

2007, 7(6): 76-79.

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In-plane ultimate bearing capacity analysis of deck-type steel braced arch bridge

ZHAO Can-hui

Abstract: In order to study the nonlinear behavior and influence factors of ultimate bearing capacity for long-span deck-type steel braced arch bridge subjected to in-plane loads, the element stiffness formulas of material nonlinear beam were derived by fibre model method, the equations used to locate element neutral position were determined, the plastic region evolution and stress redistribution of the bridge during entire loading course were analyzed, and the effects of geometrical nonlinear, interaction between arch rib and deck, construction method, loading condition for the bridge were discussed.Analysis result shows that the effects of geometrical nonlinear, interaction between arch rib and deck on the maximum stress of arch rib are less, their effect degrees are within 6%, while the influences of construction method and loading condition on ultimate bearing capacity are obvious.More>

2007, 7(6): 80-85.

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Analysis of longitudinal seismic vibration for simply-supported beam bridge

ZHOU Yong-jun, PENG Xiao-bin, ZHAO Yu, SONG Yi-fan, HE Shuan-hai

Abstract: In order to compute the seismic loads of multi-span simply-supported beam bridge, according to the deformation behavior of piers sited on elastic foundations, pier's deflection function was taken as the fundamental vibration mode, it was derived under unit force acting on pier's top, the effect of foundation deformation was taken into account, the longitudinal seismic vibration equation of the bridge was deduced by Lagrange function, and the approximate formulas of its fundamental frequency and participation factors were put forward.Simulated result shows that the first and second calculated vibration frequencies are 7.43 and 11.19 Hz respectively, and their corresponding test values are 7.00 and 10.55 Hz respectively, their errors aren't more than 5.8%, which demonstrates that the mode is appropriate for assessing the longitudinal seismic performance of the bridge.More>

2007, 7(6): 86-89.

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Long-term effect analysis of widening for concrete T-girder bridge

WEN Qing-jie, YE Jian-shu

Abstract: In order to analyze the long-term effect of widening for concrete T-girder bridge, the continuous change of stress resulted from the shrinkage and elastic modulus change of concrete in each period of time were studied, the basic formulas of shrinkage and creep were derived by using displacement method based on energy principle, the strain change of creep was analyzed by using incremental method, and corresponding calculation program was compiled.For testing the program, the calculation result of test pieces was compared with their measure result.Their relative error is 10% at the joint of new and old concretes, so the computation precision of the program is higher compared with algebraic method.The tensile stress at flange plate of new girder is 2.67 MPa under creep effect aroused by shrinkage stress and self-weight stress of new girder in 3 a, which may lead to concrete crack.For reducing the effect of shrinkage and creep, it is suggested that bridge should be widened after new girder is placed at least 6 months.More>

2007, 7(6): 90-95.

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Numerical method of bearing capacity for preloaded RC beam strengthened by bonding steel plates

REN Wei, ZHAO Yu, LUAN Hao-fa

Abstract: In order to study initial stress and ring force transfer between steel plates and concrete in the numerical analysis of RC beam strengthened by bonding steel plates, 8 scale-down models of RC beam were manufactured, their loaded whole processes were analyzed by using surface-surface contact analysis method and "birth and death" element method, and a numerical analysis method of strengthening RC beam with initial stress was proposed.Numerical analysis result shows that the deflection variation rule is consistent with its test rule, the deviation is within 11.5% in ultimate load case.Obviously, it effectively solves the problems that retrofitting structure and steel plates don't act together and how does the force transfer between concrete and steel plates in preloaded case.More>

2007, 7(6): 96-100.

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Construction modes and measures of urban rail transit

YUAN Yu-ling, WANG Xuan-cang

Abstract: In order to ensure the sustainable development of urban rail transit in China, the construction experiences of international urban rail transit were summarized, their financing structures and operation modes were studied.Taking Shenyang City as an example, the potential problems, financing and operation strategies in the development of urban rail transit in China were analyzed by using quantitative and qualitative analysis methods.Analysis result shows that the construction modes of urban rail transit can be divided into three stages, the modes of most cities in China are in the first stage, it is valuable to learn international existing experiences to exploit their advantages.The government should dominate in the development of local urban rail construction, it should be opened gradually to social capital to support the further development of rail construction and achieve an efficient and economical development mode.2 tabs, 11 refs.More>

2007, 7(6): 101-106.

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Data envelopment analysis model of harmonious relationship between urban traffic and land use

YANG Li-ya, SHAO Chun-fu

Abstract: In order to evaluate the relationship between urban traffic and land use in Chinese cities with high-density development characteristics, its evaluation indices were selected, and a data envelopment analysis(DEA)model was developed. The harmonious degrees between urban traffic and land use for 8 districts of Beijing in 1990~2005 were computed by using the model, and the key factors that influence the relationship were analyzed. Evaluation result shows that the harmonious relationship is better before 1994 and after 2004, harmonious indices equal or approach 1, while the relationship is inharmonious in 1995~2003; the contributing value of the ratio of employees to citizens is 2. 743 9, ranking first in the values of land use system indices, and that of the public transit split is 2. 733 1, ranking first in urban traffic system indices, which indicates the lower distribution rate of transit passenger flow and the unbalanced space distribution of residence and employment are two key factors that block the harmonious development between urban traffic and land use in Beijing.More>

2007, 7(6): 107-112.

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Situation evaluation of coordinated development among transportation modes

ZOU Hai-bo, WU Qun-qi

Abstract: In order to promote the coordinated development among highway transportation, railway transportation, water transportation and air transportation, according to the components of every transportation mode, a set of index system was put forward from quantity and quality aspects, and the comprehensive development level of every transportation mode was calculated by principal components analysis in 1995~2005, then the model of degree of membership for the level was set up to evaluate the coordinated situation among the modes.Evaluation result indicates that average static state coordinated degree is 0.297 8, which shows that the modes develope quickly, but their developments aren't coordinated at present.To change the uncoordinated situation, the developing opinion of the modes' inter-promoting and inter-coordinating, consummating transportation policy system, exploiting and using the modes fully, and building real comprehensive transportation hub are put forward.More>

2007, 7(6): 113-118.

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Bayesian minimum hazard control model of traffic accident

WU De-hua, CHEN Pei-jian

Abstract: For forecasting traffic accident and control accident hazard, a Bayesian minimum hazard control model of traffic accident was constructed by using Bayesian minimum theory.The displacement coordinates were collected and transformed when vehicle ran on different radii curves, if the variety ratio of speed rate grads modular appeared abnormal surge under normal condition, the auspice of traffic accident appeared.Simulation result shows that the variety ratio to time obeys Weibull distribution with three parameters under normal running condition, the auspice can be determined by using Kolmogorov checking method, so that the dynamic supervision of traffic accident is realized on freeway.More>

2007, 7(6): 119-122.

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Aided system of aircraft noise prediction around airport

XU Zhi-sheng, CENG Qing-hua, BAI Hong-yuan, WU Jun, WANG Hong-su

Abstract: To scientifically predict aircraft noise and rationally estimate noise environment around airport, the standard of noise environment in China was analyzed, noise prediction model from the technical guidelines of environmental impact assessment for the constructional engineering of civil airport was studied, an aided prediction system of aircraft noise around airport was developed, in which the evaluation index of weighted equivalent continuous perceived noise level recommended by International Civil Aviation Organization was introduced.The noise environment of a small scale airport was computed, and the computation value was compared with the measure value.Comparison result shows that the maximum error is 1.2 dB, which indicates that the calculation precision of the system is high.Moreover, the system may predict the future noise around airport, and give noise contours.More>

2007, 7(6): 123-126.

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