交通运输工程学报

Effect of asphalt content on fatigue limit for asphalt mixture

XU Ou-ming, HAN Sen, GAO Shi-jun, LIU Ya-min

Abstract: The optimum asphalt contents of asphalt mixtures were determined by using Marshell test.The fatigue performance change rules of asphalt concretes with different asphalt contents with strain levels were studied by controlled-strain beam fatigue test.The relationship model between strain level and load cycles was built.The fatigue characters of optimal asphalt content mixture and rich asphalt content mixture under different strain levels and load cycles were analyzed.The result shows that for different strain levels, the asphalt mixture flexural stiffness moduli of the two mixtures have the same rule, which reduce quickly with a sharp increase of load cycles during high strain level and tend to reduce slowly with lower strain level.The relationships of fatigue life and strain for the two mixtures are nonlinear, and low-strain curves show a typical feature of asymptote.So the two different asphalt mixtures all have the similar characteristics of fatigue limit.Rich asphalt content has little effect on the fatigue limit at high strain, and it can markedly improve the fatigue life only when strain level is lower than 100 με.Thus simply increasing asphalt content can not mean to thin the thickness of asphalt course during designing perpetual asphalt pavement.More>

2009, 9(6): 1-6. doi: 10.19818/j.cnki.1671-1637.2009.06.001

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Prediction model of bulk modulus reduction for porous asphalt pavement

PEI Jian-zhong, CHANG Ming-feng, CHEN Shuan-fa

Abstract: According to the reduction process of bulk modulus for porous asphalt pavement, the three parameters of Gompertz prediction model were calculated, a prediction model of the reduction of bulk modulus was proposed, and the change rules of air void content with time were analyzed.The result indicates that the theoretical curve and predicted curve of bulk modulus reduction are basically consistent for porous asphalt pavement with 12 years' service life.The minimum error rate between the predicted value and the theoretical value is 0.126%, and the maximum error rate is 1.997%.The air void content decreases logarithmically and the decreasing trend is smooth as the air void content is less than 16%.Therefore, the prediction model is feasible to study the bulk modulus reduction of porous asphalt pavement.More>

2009, 9(6): 7-10. doi: 10.19818/j.cnki.1671-1637.2009.06.002

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Stress pulse durations in asphalt pavement under moving load

ZHAO Yan-qing, WANG Zhi-chao, WANG Guo-zhong, TAN Yi-qiu

Abstract: The stress pulse durations of various depths in asphalt pavement at different temperatures and vehicle speeds were evaluated by using viscoelastic 3D finite element method(FEM)and simulating the traffic with moving loads which vary with time and space.The results were compared with those obtained by using Odemark method.The durations obtained from both FEM and Odemark method were used to predict the dynamic moduli of asphalt mixtures.The result shows that there clearly exists a nonlinear relationship between the stress pulse duration and the depth.The effect of temperature and speed on the duration is small on pavement surface, while it becomes significant at deeper locations.The maximal relative error of the predicted dynamic moduli is 16.1%.The study indicates that viscoelastic FEM can avoid the errors resulted from the empirical relationships and assumptions adopted in Odemark method, and thus can better represents the real behavior of asphalt pavement.More>

2009, 9(6): 11-15. doi: 10.19818/j.cnki.1671-1637.2009.06.003

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Section nonlinear analysis of salt-freezing reinforced concrete pure bending component based on damage theory

YE Ying-hua, MA Bin, SUN Yang

Abstract: Based on the experiments, the Loland model used in damage mechanics was introduced into concrete uniaxial compression analysis and the descending portion of the model was modified into nonlinear expression.The parameters of the stress-strain relationship for concrete suggested by code for design of concrete structures(GB 50010—2002)were processed by data regression fitting.Combined with the modified Loland model, the concrete salt-freezing damage constitutive model related to freezing-thawing cycle time and water-cement ratio was derived.With the compiling programs by Fortran language, the section nonlinear analysis of RC beam under salt attack, sustaining load and 400 times freezing-thawing cycles was done.The result indicates that under the action of multi-factors, with the increase of the cycle times and the ratio, the initial damage of concrete is growing, the peak stress reduces and its corresponding strain increases, but the ductility is not significant change.With the increase of continuous load, the ultimate bearing capacity of the beam decreases.More>

2009, 9(6): 16-20. doi: 10.19818/j.cnki.1671-1637.2009.06.004

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Microscopic study on dynamic behavior of lunar regolith under driving wheel in microgravity circumstance

ZOU Meng, LIU Guo-min, LI Jian-qiao, ZHANG Jin-huan, LI Yin-wu

Abstract: That rigid wheel passed lunar regolith was simulated by discrete element method(DEM), 5 typical particles and a area with a radius of 5 cm were elected, and the particle tracks, speed distributions and the dynamic process of the porosity ratio of lunar regolith under driving wheel in microgravity circumstance were analyzed.The result shows that the tracks can be separated into push, press and rebound parts when lunar regolith particles are under smooth wheel.They can be separated into two kinds when lunar regolith particles are under lug-wheel.When the particles are outside the circularity, the tracks are similar to that under smooth wheel.When the particles are inside the circularity, the tracks can be separated into press, toss and drop parts.Lunar regolith under driving wheel has ahead and retral floating areas when the slip ratio is between 0 to 100%.The porosity ratio of lunar regolith descends when the wheel passing, and then it has some rebound after the wheel passing, but as a whole it is less than that before the passage.More>

2009, 9(6): 21-25. doi: 10.19818/j.cnki.1671-1637.2009.06.005

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Dynamic response properties of two-way subgrade in bridge-subgrade transition section under moving load

LIU Sheng-chuan, WU Li-jian, SONG Er-xiang

Abstract: A 3D finite-element model was established by using finite element method to systematically study the dynamic response characteristics of subgrade in bridge-subgrade transition section of heavy haul railway under dynamic load.The response rules were summarized after analysis.It is pointed that the displacement curves of the points in horizontal direction of subgrade are assumed W shape under moving towards load.The displacement of the point at the center of loading area is largest, and the maximum displacement on the left of subgrade is larger than that on the right.More close to the loading center, the displacement change of the point is more dramatic.The result indicates that the load not only has impact on the displacements of the points on its action side, but also exacerbates the ones on the other side.Along the depth direction, the impact of load on subgrade displacement wears off.More>

2009, 9(6): 26-31. doi: 10.19818/j.cnki.1671-1637.2009.06.006

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Settlement properties of pile-plank composite foundation in passenger dedicated line

SHEN Yu-peng, LI Xiao-he, FENG Rui-ling, LI Guang-hui

Abstract: The adjusting principle of settlement on the cushion and the design theory of pile-plank composite foundation were studied.Tow kinds of designs on pile-plank composite foundation were conducted on the Wuqing section of operated Beijing-Tianjin intercity railway.The change characters of settlement-time-load and stress-time-load were contrastively analyzed in the different depthes of reinforcement layer and subjacent bed.The result shows that when the cushion is placed bellow the plank of the foundation, the pore pressure and displacement of reinforcement layer at the level of pile are larger, while the total displacement and post-construction settlement of subjacent bed are relatively smaller.Which indicates that the bearing capacity and consolidation degree of soil among piles increase significantly by inserting the cushion, and the post-construction settlement is more restricted.More>

2009, 9(6): 32-35. doi: 10.19818/j.cnki.1671-1637.2009.06.007

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Interval extension evaluation model of bridge condition

YANG Ya-xun, LI Zi-chun, LI Zi-qing, HAO Xian-wu

Abstract: In order to better reflect the service condition of bridge and reduce the influence of many subjective factors and the uncertainty of indexes weights on the condition evaluation of existed bridge, based on interval extension theory, an interval extension evaluation model of bridge condition was proposed.Experts' subjective weights and objective weights were combined as the aim weights of evaluation indexes.The correlation degrees between bridge condition and evaluation grades were calculated by interval relation function.Bridge condition was evaluated according to the maximum subordination principle.The condition evaluation result of a continuous beam bridge shows that the maximum subordination value is 0.20, which indicates the state grade of the bridge is Ⅲ, so the model can evaluate the bridge condition effectively and the evaluation result is objective.More>

2009, 9(6): 36-41. doi: 10.19818/j.cnki.1671-1637.2009.06.008

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Topology optimization simulation of framework for high-speed locomotive

ZHANG Kai-lin, ZHOU Chun-ping

Abstract: In order to obtain the most superior lightweight locomotive frame structure, based on ESO (evolutionary structural optimization), the ANSYS's birth and death of element function redevelopment were applied, the element with relatively low stress or low strain energy density was "killed" by setting a stress threshold, and the topology optimization procedure was established by APDL.The interior ribbed plate position of bogie frame for high-speed power vehicle was simulated by ESO, the optimal topological location of the interior ribbed plate was determined, and the thickness of the plate was optimized.The result shows that the stress of the end beam in bogie frame increases by about 30%, the stress of the lateral beam in bogie frame increases by about 10% after the structure is optimized, and the overall stress distribution of the frame tends even.Through framework topology and size optimization, the mass of bogie frame reduces by 143.92 kg, and the reducing rate is about 10%, so the lightweight purpose of bogie frame achieves based on the uniform strength design of bogie frame.More>

2009, 9(6): 42-46. doi: 10.19818/j.cnki.1671-1637.2009.06.009

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Influence of wheel/rail parameters on wheel profile wear of high-speed train

LUO Ren, CENG Jing, WU Ping-bo, DAI Huan-yun

Abstract: The multibody dynamics model of high-speed vehicle and the wear calculation model of wheel profile were set up.The wheel/rail contact relationship and the contact normal force were calculated by dynamics simulation.FASTSIM was used to calculate the sliding velocity, the tangential froce and the wear power dissipation in the contact patch.The wear model based on wear energy dissipation was adopted.The mass loss in a contact patch was calculated when wheelset rolled a circle.The wear depth was cumulated after vehicle ran a distance.Numerical simulation was used to study the influence of profile shape, vehicle speed, wheel back distance and rail cant on the wear depth and wear distribution of wheel profile.The result indicates that the wear regions of S1002 and LMA profiles are more even.The wear depth of LM profile is biggest.The wear regions of LM and XP55 profiles near wheel flage.When it is LMA profile with standard wheel/rail parameters, the wear depth increases with the increase of wheel back distance, and increases with the decrease of rail cant.The profile wear is closely related to the equivalent conicity.Although the profile wear is less when the equivalent conicity is smaller, the other dynamics performances should be considered when selecting the equivalent conicity.More>

2009, 9(6): 47-53. doi: 10.19818/j.cnki.1671-1637.2009.06.010

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Data-processed method of bogie parameters test rig

HUANG Biao, WU Ping-bo, YANG Shi-jie, LIU Bin-bin

Abstract: In order to obtain the correct and reasonable result from bogie parameters test, the principle of bogie parameters test rig and the reason of experimental error were analyzed.An effective and simple data-processed software for the test rig was developed by using VB and Matlab based on ActiveX technology.The error was rejected by the data-processed software.The data-processed method for positioning stiffness and bogie rotational resistance was introduced in detail.The evaluation criteria of bogie rotational resistance was summarized.The feasibility of the software was verified by processing a set of measurement data got from CRH5 bogie parameters test.The result indicates that each bogie rotational resistance is less than 0.08.Bogie rotational resistance in deflated air spring state is bigger than that in the inflated state under the same actuator loading frequency.Under the same air spring condition, bogie rotational resistance increases as actuator loading frequency increases.Therefore, it is shown that vehicle's speed and the conditions of air spring have certain impact on vehicle's curving performance.More>

2009, 9(6): 54-58. doi: 10.19818/j.cnki.1671-1637.2009.06.011

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Computational method of critical speed for rotor-bearing system

WANG Mei-ling, CHEN Guo

Abstract: A computational method of the critical speed of rotor-bearing system based on the continuous beam model was proposed.Rotor shaft was considered as equisection Euler free beam model.The supporting forces from bearings and the forces between shaft and rotor disks acted on shaft in the form of concentrated force.With modal truncation method, the partial differential equation of the system was transformed into ordinary differential equation set.The system's responses and critical speed were obtained by numerical integral method.ZT-3 type multi-function rotor test rig was used to verify the new method.The calculating critical speed is the same as the actual one, which is about 5 500 r·min^-1, so the new method is correct and effective.More>

2009, 9(6): 59-63. doi: 10.19818/j.cnki.1671-1637.2009.06.012

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Rerouting path planning based on artificial potential field algorithm

XU Xiao-hao, LI Cheng-gong, ZHAO Yi-fei, LI Xiong

Abstract: Under severe weather or flow constrained areas, a new rerouting path planning model based on artificial potential field algorithm(APFA)was proposed.Considering air traffic control(ATC)program and flight performance, linear sub-fitting method was used to fit the initial rerouting path, so that the vibration and discrete points were eliminated.A curve cut-off method was used to eliminate the extra turning points, and the final flight path was generated.Simulation result shows that the length of the rerouting path flying around expanded area boundary is 532.299 km, but the length of the new generated rerouting path is 455.924 km, the path length reduces by 14.35% under the condition that the turn points aren't added.So the flow constrained area can be avoided safely and effectively by using the proposed method.More>

2009, 9(6): 64-68. doi: 10.19818/j.cnki.1671-1637.2009.06.013

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Hub-and-spoke airline network design with uncertainty demand

DENG Ya-juan, CHEN Xiao-hong, YANG Chao

Abstract: In order to adapt to uncertainty demand for hub-and-spoke airline network, the influence factors and distribution characteristics of long-distance and short-distance traffic demands were analyzed.A stochastic and capacitated hub-and-spoke airline network design model was proposed.The model was transformed into chance-constrained programming model and solved by stochastic simulation-based genetic algorithm.Taking 15 cities of Chinese airline network planning as an example, hub-and-spoke network design with uncertainty demand was analyzed.Analysis result indicates that hub locations with certainty and uncertainty demands are almost same in the reasonable range of hub numbers, but compared with long-distance traffic demand, the route choice of short-distance demand changes greatly.The hub-and-spoke airline network with uncertainty demand has lower minimum transportation cost, and can better reflect true network performance.More>

2009, 9(6): 69-74. doi: 10.19818/j.cnki.1671-1637.2009.06.014

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Improved model of area capacity based on flight flow coupling

CHEN Wei-yu, HU Ming-hua, LIU Fang-qin

Abstract: The capacity evaluating problem of area with several sectors was studied, and the limitation of flight flow coupling existing between airspace units was analyzed.The coupling capacities of airspace units were defined, and their influecing factors were analyzed.A multi-objective integral optimization model of area coupling capacity under the constraints of controller workload was presented, and was used to calculate the coupling capacities of airspace units in Lanzhou area.Analysis result shows that the coupling capacities of sectors 1, 2, 3 are 22, 19, 33 flights·h^-1, which are less than their max capacities, and the area coupling capacity is less than the simulation evaluation result.Therefore, the model is more advantageous to distribute airspace resources.More>

2009, 9(6): 75-79. doi: 10.19818/j.cnki.1671-1637.2009.06.015

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Customer satisfaction evaluation of expressway service

ZOU Qun, ZOU Guo-ping, YU Li-jun

Abstract: The conceptions of expressway service and customer satisfaction were analyzed, a customer satisfaction model was designed, which included seven latent variables, such as customer expectation, condition perceived quality, environment perceived quality, activity perceived quality, customer satisfaction, customer complaint and customer faithfulness.Following the principles of integrality, importance, independency and maneuverability, the customer satisfaction evaluation index system of expressway service was constructed by using Delphi method from four aspects of service condition, service environment, service activity and customer complaint.Through combining fuzzy mathematics theory with analytic hierarchy process(AHP), a fuzzy hierarchy comprehensive evaluation model of customer satisfaction for expressway service was constructed, and the customer satisfaction of Nanchang-Jiujiang expressway was evaluated.Evaluation result shows that the customer satisfaction of the expressway is general satisfaction, but its service activity and customer complaint are lower satisfaction, which is consistent with the statistical data of customer satisfaction, so the model is rational and effective.More>

2009, 9(6): 80-86. doi: 10.19818/j.cnki.1671-1637.2009.06.016

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Safety analysis of highway passenger transport and modeling of vehicle brake performances

XU An, QIAO Xiang-ming

Abstract: To accurately evaluate the safety situation of highway passenger transport in China, the present condition of traffic accidents caused by long-distance passenger vehicles was reviewed, and the brake performances of long-distance passenger vehicles were detected by reaction type roller brake tester.Based on the technical methods, such as large sample data collecting, multivariable data analyzing and mathematical modeling, the brake performance distributions of these vehicles were analyzed, the optimum fitting distributions and optimum distributive parameter estimations of several brake performances were obtained, and the relevant statistical models of the brake performances were established.Analysis result shows that highway passenger transport mortality per 10 thousand vehicles is 26.828, and the mortality per 100 million vehicle-kilometers is 6.555, so the accident rate in China is still high.The brake performances of long-distance passenger vehicles obey Weibull distribution, the relative errors between statistical model volues and detecting results are all less than 2.378%, so the models are accurate and reliable.More>

2009, 9(6): 87-91. doi: 10.19818/j.cnki.1671-1637.2009.06.017

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Time points decision of single target logistics delivery based on p-median model

BAI Yang, ZHU Jin-fu

Abstract: In order to decide the best delivery time points, three cases of single delivery target were studied by using p-median model, the mathematical models of least delivery times, minimum delivery time and minimum transportation cost under the condition of freight discount were build, and taking air cargo transportation as a case, their delivery time points were calculated by using ILOG optimization software.Analysis result shows that the average delivery time of least delivery times is 1.6 times higher than the average minimum delivery time, and the delivery time of realizing minimum transportation cost under the condition of freight discount is longer than that without freight discount.So consignors or logistics service providers can choose the models to decide the best delivery time points according to customer requirements.More>

2009, 9(6): 92-96. doi: 10.19818/j.cnki.1671-1637.2009.06.018

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Correlation between inland waterway transport and local economy

LI Yue-qi, WANG Ying, ZHANG Xin, SHI Xin

Abstract: In order to discover the interaction mechanism between inland waterway transport and local economy, taking Shanghai inland waterway transport as an example, their correlation analysis models were built based on logistic curve and cointegration theory.The contribution rate of inland waterway transport to GDP was calculated respectively by using production function theory, principal component analysis, variance analysis and data envelopment analysis.Calculation result shows that inland waterway transport and local economy have similar development regulars and strong associated relationship.The growth rate of early stage increases rapidly, and then gradually slows down until the steady state.The contribution rate of inland waterway transport to local economy is about 2%~4%.More>

2009, 9(6): 97-101. doi: 10.19818/j.cnki.1671-1637.2009.06.019

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Combination evaluation method of air transport industry competence

CHU Yan-chang, YU Jian, LI Yan-wei

Abstract: Air transport industry competence was evaluated by using combination evaluation method, and its denotation and influencing factors were analyzed.A competence evaluation index system of air transport industry was built, the weights of evaluation indices were determined by synthetical weight method, and air transport industry competences of China, USA, Germany, Singapore, Japan and Korea from 2004 to 2006 were studied.Analysis result indicates that the competence order is USA, Germany, Singapore, Japan, Korea and China from strong to weak in 2006.The evaluation result can reflect the general level of every county objectively, so the evaluation method is reasonable.More>

2009, 9(6): 102-109. doi: 10.19818/j.cnki.1671-1637.2009.06.020

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Lateral collision risk model based on CNS position error

ZHANG Zhao-ning, SHEN Jin-wei, LIU Ji-min

Abstract: In order to confirm the safe separation of routes and evaluate the collision risk effectively, the lateral collision risk based on CNS (communication, navigation and surveillance) position error was studied.The multi-dimensional random variable covariance matrix was applied to gain the distribution function of the lateral position error under CNS environment, then the lateral collision risk model under CNS position error was established, and an example was calculated.Analysis result shows that the lateral collision risk of studied route is 4.8×10^-13, which is in the safety target level of 5.0×10^-9, so the route under existing CNS environment is safe.More>

2009, 9(6): 110-113. doi: 10.19818/j.cnki.1671-1637.2009.06.021

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Impact of traffic guidance information on vehicle behavior in network

WEI Yun, FAN Bing-quan, HAN Yin, GAN Hong-cheng

Abstract: To study the effect of traffic guidance model, cellular automata(CA)model was applied to simulate vehicles' behaviors in traffic network, and the impacts of different guidance informations on traffic flow were studied in different traffic volumes and different accepting guidance ratios.A traffic guidance model based on agent technology was built.In which Q-learning algorithm was used to optimize traffic guidance information, propositional information could be provided according to real time network traffic, traffic flow distribution was adjusted.Simulation result shows that the factors that impact guidance effect in network are accepting guidance ratio and guidance information, traffic guidance model based on agent can effectively balance network traffic flow, which is better to heavy traffic flow.In light traffic flow, the model has a little advantage compared with normal model, but in heavy traffic flow, propositional guidance information can decrease 12% average travel time compared with descriptive guidance information.More>

2009, 9(6): 114-120. doi: 10.19818/j.cnki.1671-1637.2009.06.022

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Verification method of resident trip OD matrix based on screen area

FAN Da-ke, LUO Xiao-qiang, CHEN Kuan-min

Abstract: In order to improve the verification precision of resident trip survey, the characteristic of screen line was studied that could form a lot of closed areas in cluster city, and the verification method of resident trip OD matrix based on screen area was proposed according to maximum entropy principle.The relationship between the inner or outer traffic volume of screen area and OD matrix distribution, and the relationship between the OD matrix distribution of screan area and the traffic volume of road segments were analyzed.The difference minimum between the real values and estimation values in screen line segment and screen area was seen as target, and the corresponding model and algorithm were set up.The method was verified by the data of Xi'an urban resident trip survey in 2008.Analysis result indicates that the mean relative error between the assignment volume of verified vehicle OD matrix and observed data is 4.75%, and the maximum error is 12.28% in 519 traffic zones, so the method is valid.More>

2009, 9(6): 121-126. doi: 10.19818/j.cnki.1671-1637.2009.06.023

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