交通运输工程学报

Gyratory compaction characteristic of SBS warm mixed asphalt mixture

ZHANG Jiu-peng, PEI Jian-zhong, XU Li, XING Xiang-yang

Abstract: Superpave gyratory compacter (SGC) was used to make the specimens of SBS warm mixed asphalt mixture (WMA), and the volume characteristics of WMA were compared with hot mixed asphalt mixture (HMA) to determine the reasonable mixing temperature. Furthermore, the slopes and densification energy indexes of SGC compaction curves were introduced to reflect the inherent compaction characteristics of asphalt mixtures. Analysis result indicates that the determined compaction temperature of WMA is lower than HMA by 20 ℃, the dynamic stability of WMA improves by 30%, but its crack resistance at low temperature and its water stability change a little. In the initial stage, the slope of densification curve of HMA is 2.53, and the densification energy index is 0.246. The slope of densification curve of WMA is 3.14, and the densification energy index is 0.156. The result indicates that WMA has better construction workability. In the later stage, the slope of densification curve of HMA is 0.019 5, and the densification energy indexes are 1.95 and 1.65. The slope of densification curve of WMA is 0.015 2, and the densification energy indexes are 2.61 and 2.00. The result indicates that WMA has better capacity to resist the densification under traffic load.10 tabs, 5 figs, 12 refs.More>

2011, 11(1): 1-6. doi: 10.19818/j.cnki.1671-1637.2011.01.001

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Calculation method of equivalent modulus of elasticity for foundation of airport pavement

WANG Zhen-hui, CAI Liang-cai, HUANG Ming-hui, WU Ai-hong, LU Yang

Abstract: Based on the elastic multi-layer theory and the principles of displacement equivalence, the influence of pavement structure parameters, aircraft load radius and main canding gear types on the equivalent modulus of elasticity of foundation(EMEF) was studied.On the basis of 126 kinds of representative pavement structures, the EMEF regression formula was established, and the accuracy of regression formula was verified by using the back calculation solution of equivalent modulus according to the elastic multi-layer theory.Analysis result indicates that when the aircraft load radius and mail canding gear types are considered, aircraft load radius ranges from 10 cm to 40 cm, and the calculation errors of the EMEFs are less than 4%.So the formula is extensional, simple and practical, the calculation result is accurate.More>

2011, 11(1): 7-12. doi: 10.19818/j.cnki.1671-1637.2011.01.002

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Deformation prediction of structured soft clay under cyclic load

JIANG Yan, LEI Hua-yang, ZHENG Gang, YANG Xiong-jian

Abstract: In order to analyze the deformation characteristics of structured soft clay in Tianjin Binhai New Aera, dynamic triaxial test was conducted under traffic load, soil structure's yield pressure was considered based on the disturbed state concept, a disturbed function was put forward which considered the gradual destruction of soil structure under cyclic load, an empirical formula of plastic deformation was proposed and vertified by using the test. Analysis result shows that the relationship between accumulative plastic strain and cyclic number under cyclic load is divided into stable type and destroyed type. Accumulative plastic strain increases with the increase of cyclic number. There exists a critical cyclic stress ratio under the same confining pressure. The maximum of critical cyclic stress ratio decreases with the increase of confining pressure. Obviously, the empirical formula reflects the deformation characteristics of soil under traffic loadi.More>

2011, 11(1): 13-18. doi: 10.19818/j.cnki.1671-1637.2011.01.003

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Analysis method of stability and critical speed for train-track (bridge) time-variable system under lateral vibration condition

XIANG Jun, CENG Qing-yuan

Abstract: On the basis of the mechanism of train derailment caused by unknown reasons and the energy increment criterion for checking the stability of equilibrium state of a system in motion, the analysis method of lateral vibration stability of train-track(bridge) time-variable system and the calculation methods of critical speed and admissible limit speed for the system under lateral vibration condition were put forward. Under lateral vibration condition, for the system, the maximum input energy and its increment were determined, the limit resistant force working and its increment were calculated, the judging rules of vibration stability were set up, and the critical speed was computed. Through an example, the lateral vibration stability of high-speed train and ballastless track system and the running safety control indexes of high-speed train were calculated. Computation result shows that the critical speed of the system is 647.3 km·h^-1, the admissible limit speed is 517.84 km·h^-1, and the anti-derailment safety degree is 1.85. So, high-speed train safely runs on ballastless track at the design speed of 350 km·h^-1.More>

2011, 11(1): 19-24. doi: 10.19818/j.cnki.1671-1637.2011.01.004

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Finite element analysis of wheel/rail thermo-contact coupling effect

SUN Chuan-xi, ZHANG Jun, WANG Chun-yan

Abstract: Aiming at the thermal stress caused by brake, a thermo-contact coupling calculation method was used to simulate the process of wheel/rail thermal contact based on finite element method. The temperature field and displacement field were synchronously solved by using coupling equations. The distributing and varying rules of the stresses for wheel and rail were studied under pure mechanical load condition and thermo-contact coupling condition. The relation among the displacements, temperatures and stresses of wheel's and rail's surfaces and second surfaces were analyzed. Analysis result shows that affected by the thermal stress, the maximum equivalent stress of wheel's surface rises by 18%, and the area with high stress varies from 1-4 mm to 0-3 mm below the surface.More>

2011, 11(1): 25-30. doi: 10.19818/j.cnki.1671-1637.2011.01.005

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Lightening design of carbody structure for heavy haul gondola

YAO Shu-guang, TIAN Hong-qi, XU Ping

Abstract: The bearing structure mass of carbody was taken as objective function, the component thicknesses were taken as design variables, the structure stresses and deformations from key load cases were taken as constraint conditions, and an optimization mathematic model of carbody bearing structure for ore gondola with axle load 40 t was established. A new unconstrained objective function was set up via penalty function against constrain, the searching direction was decided according to conjugate gradient method, and the objective function was approximated by using least squares technique. Using parametric design language APDL, the iteration computation of mass minimization for carbody was performed based on the second development platform of FEA software ANSYS. Analysis result indicates that the 1/4 mass of carbody structure reduces from 1.939 5 t to 1.760 7 t, the relative mass loss rate is about 9.22%, the ratio of lighting mass to loading capacity is 0.16, and its strength and stiffness still meet the corresponding standard and design specification requirement.More>

2011, 11(1): 31-35. doi: 10.19818/j.cnki.1671-1637.2011.01.006

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Geometric design method of wheel profile for improving wheel and rail contact status

ZHANG Jian, WANG Yu-yan, JIN Xue-song, CUI Da-bin

Abstract: The geometric design method of wheel profile was improved, its analytic mathematic expressions were presented, which connected wheelset equivalent conicity and wheel and rail contact status. The wheel and rail contact geometry, non-Hertzian rolling contact and vehicle dynamics performance of design example were calculated. Analysis result indicates that wheel and rail geometric contact points become homodisperse. Due to contact patch area increases by about 23%, the maximum contact pressure decreases by about 21%, wheel and rail rolling contact stress decreases by 20% approximately. Vehicle equipped with the example profile has nearly the same critical speed with LMA wheel profile, and because wheelset equivalent conicity has a little bit increase, the example profile exhibites better curving performance than the latter. So the method can improve wheel and rail contact status, which is beneficial to wheel and rail wear spreading, and is helpful to mitigate wheel and rail rolling contact fatigue.More>

2011, 11(1): 36-42. doi: 10.19818/j.cnki.1671-1637.2011.01.007

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Guiding mechanism of longitudinal coupling bogie with independently rotating wheels

XU Ming-chun, CENG Jing

Abstract: From the angle of creep forces between wheels and rails, the guiding mechanism of longitudinal coupling bogie with independently rotating wheels (IRW) was studied. Full vehicle dynamics models of different IRW bogies were built, and the guiding performances of longitudinal coupling IRW bogie, lateral coupling IRW bogie and full IRW bogie were investigated and compared through numerical simulation. Calculation result shows that the longitudinal coupling IRW bogie has good centering ability on straight line and good guiding on curve. During curve negotiation, longitudinal coupling IRW bogie has enough wheel/rail longitudinal creep force compared with lateral coupling IRW bogie. The attack angle of leading wheelset is smaller and only half of the value of full IRW bogie. Wheel/rail wear significantly reduces, and is about one-third of the value of full IRW bogie. Other curving performance indexes are also superior to full IRW bogie. It can be seen that longitudinal coupling IRW bogie has good guiding capability.More>

2011, 11(1): 43-50. doi: 10.19818/j.cnki.1671-1637.2011.01.008

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Real-time distance measurement system based on Doppler ranging radar

JIA Li-shan, WANG Li-wen

Abstract: The working principle of dynamic detection technology for the luminous intensity of airport aid lights was researched, and the character of distance measurement in the dynamic detection of luminous intensity was analyzed. Based on the principle of Doppler ranging radar, a non-touch real-time distance measurement system was built. Combining with hardware card, measurement software was designed by using object oriented method. According to the multithread technology, the distance measurement and the light illumination measurement were made in different threads. The whole process of dynamic measurement of luminous intensity was autocontrolled. Test result shows that the synchronization of distance measurement and light illumination measurement is realized by using the system, the error of distance measurement is 5 mm, the process of dynamic measurement of luminous intensity can be controlled by using the distance measurement precisely, and the control precision of distance between illumination measurement points is up to 0.000 5%. So the system has good real-time performance, high measurement precision, and satisfies the request of real-time precise distance measurement.More>

2011, 11(1): 51-57. doi: 10.19818/j.cnki.1671-1637.2011.01.009

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Influence of road condition on running safety in atrocious weather

HE Jie, LIU Xia, CHEN Yi-kai, ZHAO Chi-hang

Abstract: In order to research the influence of road condition on running safety in atrocious weather, vehicle dynamics model, road model and vehicle-road coupling model were set up by using multi-body dynamics software ADAMS/Car. By changing road friction coefficient, road conditions in sunny day, rain, snow and freezing weather were simulated. Two virtual tests of single lane change and step steering were carried out, and the response outputs of lateral displacement, course angle and lateral force of tires were obtained. Computation result indicates that when road friction coefficient in snowy weather is 0.28, vehicle speed is 50 km·h^-1 in the single shift line simulation, the lateral displacement of vehicle will reach 4.50 m, the vehicle will overrun runways and have a risk of collision. When vehicle speed is 40 km·h^-1 in the step steering simulation, vehicle will go haywire.More>

2011, 11(1): 58-63. doi: 10.19818/j.cnki.1671-1637.2011.01.010

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Mixed clustering algorithm of airport capacity in stochastic GHP model

WANG Fei, XU Xiao-hao

Abstract: In order to make full use of airport capacity resources and eliminate existing human prediction error in stochastic ground holding policy(GHP) model, a mixed clustering algorithm was researched. Daily capacity was divided into several intervals in accordance with 30 min, each interval corresponded to a certain capacity value, and the capacity of one day was a capacity scenario. The capacity scenarios of an airport in half a year were collected, typical capacity scenarios were produced by using self-organizing-maps(SOM) neural network and k-means clustering algorithm, and the probability of each capacity scenario was calculated. Typical capacity scenario tree was constructed and applied in stochastic static and dynamic GHP models. Simulation result shows that compared with no-GHP case, the total delay costs of static and dynamic GHP models reduce by 32.7% and 52.7% respectively. So the mixed algorithm is feasible, and the typical capacity scenario tree is practical.More>

2011, 11(1): 64-68. doi: 10.19818/j.cnki.1671-1637.2011.01.011

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Obstacle assessment of parallel double-runway airfield clearance

LUO Cheng-li, CAI Liang-cai, ZHANG Luo-li, MENG De-shan

Abstract: Military airfield clearance specification was analyzed, the mathematical models of obstacle limit surfaces for single runway and parallel double-runway airfield clearances were built. Based on the models, the triangle mesh elevation model of parallel double-runway airfield clearance was built by using ArcGIS, and the 3D display result was got. Parallel double-runway airfield clearance obstacles were evaluated by superimposing digital elevation model (DEM) with corresponding topographic maps. Analysis result indicates that the actual elevations of obstacles O₁, O₂, O₃ are respectively 76, 248, 413 m, the heights of clearance limit surfaces are respectively 60, 245, 380 m, and the exceeding heights are respectively 16, 3, 33 m. So the obstacles of parallel double-runway airfield clearance are evaluated by using the method quickly and exactly, and evaluation efficiency improves greatly.More>

2011, 11(1): 69-73. doi: 10.19818/j.cnki.1671-1637.2011.01.012

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Reserve depot location of railway emergency material

LONG Jing, HUANG Gang, WANG Meng-jun, ZHANG Yan-chun

Abstract: In order to solve the reserve depot location problem of railway emergency material with the restrictions of response time and minimum number of reserve depots, complex railway network was simplified to sections by analyzing the uniqueness of the problem. A mathematic model was established relying on supply and demand matrix, and its solving program with improved branch and cut search method was introduced. The reserve depot location problem of a railway bureau was taken as an empirical analysis. Analysis result indicates that choosing Yanliang as reserve depot is correspond to reality, the model simplifies complex railway network to sections with the premise of ensuring the consistency of effective solution, and eliminates the constraint of point covering line, so the model is more applicable to the reserve depot location problem of railway emergency material.More>

2011, 11(1): 74-78. doi: 10.19818/j.cnki.1671-1637.2011.01.013

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Analysis of speed control behavior for driver on mountain highway

SHAO Yi-ming, MAO Jia-chuan, LIU Sheng-chuan, XU Jin

Abstract: The relationship between road geometric characteristic and driving speed was analyzed based on driving experiments and observation data on highways. The mathematic models of acceleration, deceleration and driver's speed control behavior on curve, entering or leaving curve, driving on tangent were obtained, and desired speed profiles along road were generated by the models. A car dynamics model was created by using mechanical dynamics analysis software ADAMS, roadway module was developed by using VB6.0, driver module was developed by using VC++7.0. At the simulation beginning, desired speed and desired path were generated, the car followed them in preview strategy, and the autonomous driving of car was achieved. Simulation result shows that desire speed and desired path change in a same trend with actual driving speed and path. Desired speed can be as the objective for car to follow, it adapts car dynamics characteristics, and can guide the driving of car on complex mountain highways safely.More>

2011, 11(1): 79-88. doi: 10.19818/j.cnki.1671-1637.2011.01.014

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Single-vehicle accident modelling method on freeway

YANG Hong-zhi, YE Ya-li, XU Jin-liang, ZHONG Chun-yao

Abstract: The collected single-vehicle accidents were analyzed by using random trial and mathematic equalization principle. The area function of single-vehicle accident rate was computed by definite integral element method. The affecting factors and geometric variables of traffic accident were selected one by one according to the change rule of area function, the affecting model of every variable was set up, and the final variables were determined. The single-vehicle accident forecast models were established in the sections with different radiuses and linear lengths by using regression analysis. The suitable curve radius and linear length were proposed through analyzing the 3D surface charts of the models. Research result indicates that in freeway design, the reasonable radius of a curve is in the interval [2 500, 3 500], and a linear length is in the interval [1 000, 2 000] for the alignment combination of straight line-curve-straight line. When the radius of curve is more than the minimum radius without superelevation, it is 1 000 for the linear length of that is connected with the curve.More>

2011, 11(1): 89-94. doi: 10.19818/j.cnki.1671-1637.2011.01.015

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Solution of vehicle routing problem with backhauls considering cost of arranging freight in carriage

XING Zhan-wen, GUO Xiao-fen, WEI Juan

Abstract: Considering the cost of arranging freight in carriage, a mathematic model of vehicle routing problem with backhauls was set up, and was solved by using tabu search algorithm. The vehicle routes of a large logistics enterprise with its intraday tasks including delivery and collection business in Beijing were optimized by using the model and the algorithm, and the optimization was completed in 5 s. Calculation result shows that under the condition that the total distance increases by 7.8%, the distribution cost of vehicle reduces by 24.5% compared with saving algorithm, and the equilibrium value increases by 9.3%. The model and the algorithm reduce the workloads of dispatchers and save the transport costs of logistics enterprises.More>

2011, 11(1): 95-99. doi: 10.19818/j.cnki.1671-1637.2011.01.016

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Signal coordination control optimization model of intersection and cross walk

CHEN Xiao-hong, QIAN Da-lin, HUANG Jun-hong

Abstract: The effect of pedestrian crossing on road traffic flow was analysed, and the formulae of average delaies of vehicles at the imports of intersection were determined. A signal coordination control optimization model between intersection and cross walk was built based on arterial road coordinate control systems. The mininum total delay and maximum capacity of intersection were taken as objective functions, the shortest crossing times were taken as constrain conditions, and the green times of phases and offsets were taken as control parameters. As the parameters were co-optimized, genetic algorithm was resorted to solve the model. Computation result shows that compared with actual datat, total delay reduces by 35.4%, and traffic capacity increases by 0.1%. Total delay reduces by 81.3% compared with traditional Webster method. So the model is feasible and can improve the traffic efficiency of intersection.More>

2011, 11(1): 100-106. doi: 10.19818/j.cnki.1671-1637.2011.01.017

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Ontology model of information sharing for heterogeneous GIS-T in freeway network

GUO Jun-jie, YAN Mao-de, CHEN Yin-san

Abstract: In regard to the heterogeneous problem of GIS-T information representation in Chinese freeway network, an ontology-based solution for information sharing in GIS-T was proposed by studying the reasons of heterogeneity. A freeway network ontology (FNO) model was set up with traffic information units as abstract topology, geometrical components, linear reference system, attached facilities and dynamic data. The consistent representation of transport information with FNO was explained in the case study of suburban freeway network surrounding Xi'an. Analysis result shows that all GIS-Ts have the common understanding of transport information according to the consistent semantics implied from FNO, and better perform transport information sharing. So FNO model is capable of increasing the interoperability of heterogeneous GIS-T, and promotes the upper applications such as transport information management, integrating and sharing.More>

2011, 11(1): 107-113. doi: 10.19818/j.cnki.1671-1637.2011.01.018

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Calculation model of speed-limit value for traffic accident scene section on freeway

ZHANG Wen-hui, XU Hong-guo

Abstract: Based on the ability of processing information within the dynamic sights and visual fields of drivers, a calculation model of speed-limit value for traffic accident scene section was set up. According to the information characteristics of road and environment, traffic flow, traffic management, drivers, irrelevant personnel and weather, the occurrence probabilities of different informations were quantitated by using ergonomics theory. The speed-limit values were calculated in typical freeway accident scenes referring to the information characteristics. Calculation result shows that the speed-limit value is 70 km·h^-1 in one-lane enclosed accident scene of bidirectional four-lane freeway. In one-lane and two-lane enclosed accident scenes of bidirectional six-lane freeway, the values are 80, 60 km·h^-1 respectively. In one-lane, two-lane and three-lane enclosed accident scenes of bidirectional eight-lane freeway, the values are 80, 70 and 60 km·h^-1 respectively.More>

2011, 11(1): 114-118. doi: 10.19818/j.cnki.1671-1637.2011.01.019

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Effects of vehicle speed and traffic sign text height on drivers' visual search patterns

YUAN Wei, FU Rui, MA Yong, GUO Ying-shi

Abstract: The simple traffic environment in experimental field on linear section was simulated. Vehicle speed and traffic sign text height were taken as controlled variables. Eye movement data, such as horizontal and vertical visual angles and gazing times (fixation duration) were collected from 7 participant drivers by using eye movement tracking device. The effects of vehicle speed and traffic sign text height on the experimental data, such as the variances of visual search, fixation duration and visual angular dispersion were explored by analysis of variance (ANOVA). Analysis result indicates that vehicle speed and traffic sign text height have little significant effect on drivers' visual search extents. The F value of vehicle speed is 2.99, which is less than the critical test value 3.55, and the F value of traffic sign text height is also less than 3.55. Drivers' mean fixation durations are effected slightly by vehicle speed and traffic sign text height, and the F values of the two factors (0.09 and 1.20) are less than the critical test value 3.17. Drivers fixate mostly on road centre area, and all drivers' percent fixating on road centre under different experiment conditions exceeds 60%, and especially the areas on the left side and closer to vehicle. Drivers spread their fixations to the far side gradually with the increase of vehicle speed.More>

2011, 11(1): 119-126. doi: 10.19818/j.cnki.1671-1637.2011.01.020

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