2011 Vol. 11, No. 6

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Road and railway engineering
Mesomechanics simulation of micro-crack extension process for asphalt mixture
LI Rui, CHANG Ming-feng, LI Yan-wei, SHI Xin, DU Qun-le
Abstract: Marshall numerical specimens of asphalt mixture were made by using discrete element method, indirect tensile test was conducted, the influences of parallel-bond strength ratios, particle friction coefficients and loading velocities on micro-crack extension processes were studied, and the mesomechanics responses of particles in the specimens were analyzed.Simulated result indicates that the bonding characteristics of asphalt are more obvious when the parallel-bond strength ratio is larger, which makes the types of micro-cracks change from normal micro-cracks to tangential micro-cracks.When the ratio changes from 0.500 to 4.000, the contact force reduces by 78.05%, and the displacement reduces by 78.57%.The roughness of aggregate increases with the increase of friction coefficient.When the coefficient changes from 0.3 to 0.7, the contact force increases by 31.21%, and the displacement reduces by 21.45%, but there is little effect on the distribution of micro-cracks that are mainly normal micro-cracks.When the loading velocity changes from 0.03 mm·s-1 to 0.07 mm·s-1, the contact force increases by 3.50%, and the types and numbers of micro-cracks and the amounts of displacements do not change basically.Loading conditions have less effect on micro-crack extension compared with asphalt and aggregate.More>
2011, 11(6): 1-9. doi: 10.19818/j.cnki.1671-1637.2011.06.001
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Recycling behavior of recycling agent on aged asphalt
ZHOU Zhi-gang, YANG Yin-pei, ZHANG Qing-ping, GAO Ji-yang
Abstract: The action mechanism of recycling agent on aged asphalt and the influence on the performance indicators of recycling asphalt were studied, Fourier transform infrared spectroscopy test and the component test of recycling asphalt were used to analyze the role of recycling agent on aged asphalt.The nonlinear relationship model of recycling asphalt component content and recycling agent mixing ratio was proposed.Depending on the experimental results of Brookfield viscosity, penetration and dynamic shear rheometer(DSR) for recycling asphalts with different recycling agent mixing ratios, the improvement of recycling agent on aged asphalt properties was analyzed, relationships among recycling agent mixing ratio and every index were summarized.Test result shows that there is no chemical reaction between recycling agent and aged asphalt, the interrelated coefficient of nonlinear relationship model for recycling asphalt component content and recycling agent mixing ratio is above 0.98.Viscosity sensitivity decreases, and penetration sensitivity increases with the increase of recycling agent mixing ratio.The logarithms of complex modulus and anti-rutting factor have good linear decreasing relationships with recycling agent mixing ratio, and the mixing ratio should be determined by recycling asphalt mixture performance test.More>
2011, 11(6): 10-16. doi: 10.19818/j.cnki.1671-1637.2011.06.002
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Feasibility of predicting settlement of medium compression soil foundation with centrifuge model tests
JIANG Guan-lu, HU Run-zhong, LI An-hong
Abstract: Centrifuge-stopped loading method and acceleration-variable centrifuge-run loading method were carried out by using TLJ-2 geotechnical centrifuge, the settlement characteristics of medium compression soil foundations of Haidong High-speed Railway and Jiaoji High-speed Railway were researched and compared with that of field-filling tests, and the main factors influencing the precisions of predicting prototype foundation settlement with centrifuge tests were studied.Research result indicates that the settlements from centrifuge tests are larger than that from filling tests, and their correction factors decrease and the settlement differences increase with the increase of foundation depth.The settlements within 6.0 m from filling tests are more than 45% of total settlement, but the settlements from centrifuge tests are less than 20% of total settlement.The properties of the settlements from two centrifuge tests are similar, the settlements in subgrade filling are 88% of total settlements, but the settlement from the first method is about twice of that from the second method.Obviously, it is very hard to predict the foundation settlement of medium compression soil by using centrifuge tests, but the tests can be used for qualitative analysis.More>
2011, 11(6): 17-23. doi: 10.19818/j.cnki.1671-1637.2011.06.003
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Strength properties of lime-fly ash loess under freezing-thawing cycles
ZHANG Zhi-quan, HU Zhi-ping, ZHAO Jie
Abstract: For lime-fly ash loess, the water-saturated strength test, the strength test at different ages under 6 freezing-thawing cycles and the strength increasing test after 1 freezing-thawing cycle were carried out, and the strength properties were analyzed.Analysis result shows that the strength of lime-fly ash loess grows slowly with age, and the water-saturated strength of long age lime-fly ash loess only reduces by 2.4%.The strength of early age lime-fly ash loess after 1 to 6 freezing-thawing cycles decreases by 19.0% evenly.The strength of long age lime-fly ash loess after 6 freezing-thawing cycles is essentially same, and only decreases by 2.4%.The water-saturated strength of early age lime-fly ash loess decreases by 47.9% evenly after 6 freezing-thawing cycles, and the strength average decreases by 41.9% after 4 freezing-thawing cycles.The water-saturated strength of long age lime-fly ash loess decreases by 14.6% evenly after 6 freezing-thawing cycles, and the strength average decreases by 7.5% after 4 freezing-thawing cycles.When the lime-fly ash loesses with 3, 7, 14, 28 d ages under 1 freezing-thawing cycle are conserved to 90 d, the long age strength average decreases by 4.0%.Therefore, the long age lime-fly ash loess has completed 60% of strength increase, and has better water stability and freezing-thawing stability.More>
2011, 11(6): 24-30. doi: 10.19818/j.cnki.1671-1637.2011.06.004
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Settlement prediction model of super large bridge for passenger dedicated railway
ZHANG Wen-sheng, CUI Zhi-wei
Abstract: Aiming at the settlement of super large bridge for passenger dedicated railway, the calibration method of chaotic behavior was put out.The nonlinear theory and chaotic time sequence method were used, and the settlement prediction model of super large bridge for passenger dedicated railway was set up.Based on embedding theory, the settlement time sequence of super large bridge was reconstructed.Through calculating the values of correlation dimension, Kolmogorov entropy and maximum Lyapunov exponent, the chaotic behavior characteristic of time sequence was verified.The piers A and B of a super large bridge for Shijiazhuang-Wuhan Passenger Dedicated Railway were taken as examples, and the settlements were calculated.Calculation result shows that by using the settlement prediction model, the maximum settlement of pier A is 0.072 5 mm, and the minimum settlement of pier A is 0.020 1 mm.The maximum settlement of pier B is 0.069 7 mm, the minimum settlement of pier B is 0.030 4 mm, and the errors between prediction values and actual values are less than ±0.005 0 mm.So the prediction model is effective, and the prediction results meet the technical requirement of bridge settlement deformation monitoring.More>
2011, 11(6): 31-36. doi: 10.19818/j.cnki.1671-1637.2011.06.005
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Transportation vehicleeng ineering
Running adaptability of high-speed EMU
LUO Ren, CENG Jing, DAI Huan-yun, TENG Wan-xiu
Abstract: A nonlinear dynamics simulation model of vehicle system was set up for high-speed EMU(electric multiple units).The actual running conditions were considered, the numerical simulation method was adopted to research the running adaptability and stability of EMU, and the matching relationships of wheel profile wear and wheel/rail contact geometry, primary guiding stiffness and equivalent conicity were analyzed.Analysis result indicates that wheel/rail matching relationship and vehicle suspension parameters are the most important factors affecting the running adaptability.The hollow wear of wheel tread has greater influence on the running stability than the uniform wear with the same wear depth.The bogie with large guiding stiffness is unstable when the low conicity tread is used, while the bogie with small guiding stiffness is also unstable when the equivalent conicity increases because of wear.In the design process of EMU, the proper wheel/rail profile matching relationship and suspension parameter optimization are determined according to the dynamics requirement of running line.For the bogie with small primary guiding stiffness, LMA type wheel tread with small initial conicity is used.While for the bogie with large guiding stiffness, wheel/rail matching relationship with equivalent conicity larger than 0.10 is required.During EMU operation, the hollow wear of wheel tread should be prevented, and the reasonable rail profile is maintained through grinding rail.More>
2011, 11(6): 37-43. doi: 10.19818/j.cnki.1671-1637.2011.06.006
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High-frequency vibration characteristics of wheels in wheel-rail system
LIU Lin-ya, LIU Hai-long, LEI Xiao-yan
Abstract: A coupling vibration model of vehicle-track-subgrade system was established, track irregularities and the contact filters in wheel-rail contact areas were considered, and wheel-rail vertical random forces were simulated.A 3D entity finite element model of wheel system was established, three contact positions were considered, including the nominal contact point, rim and lateral of wheel, and the vibration characters of wheel system in high-frequency domains due to vertical random forces were analyzed.Analysis result shows that the vibration acceleration responses of wheel rim, radial plate and wheel hub are 870, 493 and 457 m·s-2 respectively when train runs on ballast track at 200 km·h-1, the response of rim is highest, and the response of wheel hub is lowest.When the nominal contact point, rim point and outer of wheel were excited respectively, the vibration acceleration responses of radial plate are 563, 492 and 301 m·s-2 respectively, the vibration response of radial plate due to the excitation on the nominal contact point of wheel is highest.The high-amplitude vibration spectrum of each part of wheel distributes in 1 000-3 000 Hz, and the frequencies of the maximum vibration acceleration on wheel are about 1 400 Hz, the vibration responses in higher-frequency domains are not prominent due to the strong role of wave number filter.More>
2011, 11(6): 44-49. doi: 10.19818/j.cnki.1671-1637.2011.06.007
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Numerical simulation of airliner cabin door under explosion impact loading and reinforcement experiment
LIU Ying, ZUO Dun-wen, WANG Yao-hua, ZHAO Jun, YAN Hai-chun, JI Chong, HE Ji-xian
Abstract: A combination method of theoretical analysis, numerical simulation and model explosion test was used, the structure and stress state of airliner cabin door edge were analyzed, and the mechanical model was set up to describe the forced location of cabin door edge. Aimed at the forced location of door edge subjected to explosion impact loading, numerical simulation was put up by using the Explicit module of finite element software ABAQUS. The necessity and difficulties of door edge reinforcement were analyzed, reinforcement measures were proposed, and the results of explosion test and numerical simulation were compared. Analysis result shows that airliner cabin door edge cann't bear explosion impact loading, and must be reinforced. The mean thickness of pressure-reducing plates is 5 mm, the mean thickness of reinforcement plates is 6 mm, the total weight of reinforced members is 3.98 kg, and reinforcement measure is effective.More>
2011, 11(6): 50-55. doi: 10.19818/j.cnki.1671-1637.2011.06.008
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Numerical calculation of fire flue gas filling in ship engine room with multilayer structure
WANG Liang, SU Shi-chuan
Abstract: Based on large eddy simulation, the filtered balance equations and the Smagorinsky subgrid-scale model of fire in ship engine room with multilayer structure were established.Second-order finite difference method was used to disperse spatial variables, explicit second-order predictor-corrector scheme method was used to disperse flow variables, and explicit second-order Runge-Kutta method was used to disperse time variables.Velocity field, temperature field, flue gas concentration and the height of flue gas layer were solved respectively, and the change laws of fire flue gas filling in ship engine rooms with multilayer structure and monolayer structure were analyzed.Analysis result shows that the spread speed and area of flue gas in multilayer structure are greater than those in monolayer structure.When ship engine room with monolayer structure is full of flue gas, filling time is 200 s, while the filling time of ship engine room with multilayer structure is 1 500 s.Under two structures, the temperatures of cold air layer and hot flue gas layer almost increase at first then decrease, the maximum temperatures at the tops of ship engine rooms are 170 ℃, 250 ℃ respectively, however, the maximum temperatures at the bottoms of ship engine rooms are 175 ℃, 100 ℃ respectively.More>
2011, 11(6): 56-61. doi: 10.19818/j.cnki.1671-1637.2011.06.009
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Influence of eddy current retarder on vehicle braking force utilization
ZHANG Yan, LIU Cheng-ye, HE Ren, BEI Shao-yi, YUAN Chuan-yi, ZHAO Jing-bo
Abstract: When vehicle was on the roads with different road adhesion coefficients, the influence of eddy current retarder at different gears on vehicle braking performance was investigated.The ideal braking force distribution curves of front and rear wheels and front and rear arresters were studied, and their matching relations were analyzed.The concept of braking force utilization was introduced to reflect braking performance, and the braking force utilization algorithms were deduced based on different matching relations.When the retarder of a light passenger car was at different gears, the relation between braking force utilization and road adhesion coefficient was analyzed based on numerical analysis method.Study result indicates that when retarder works, braking force utilization first increases and then decreases with the increase of road adhesion coefficient.Braking force utilization is above 90% when retarder is at low gears, and road adhesion coefficient is between 0.06 and 0.81, the braking force utilization has a downward trend with the increase of retarder gear, so retarder should not be working at the highest gear for long time.More>
2011, 11(6): 62-67. doi: 10.19818/j.cnki.1671-1637.2011.06.010
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Transportation planning and management
Transportation status of Chinese expressway network in 2010
CHEN Yin-san, LI Bin, XIAO Run-mou
Abstract: Based on the database of expressway network toll system and the typical sampling investigation data at toll stations, the transportation status of Chinese expressway network was analyzed.Analysis result shows that compared with the transportation status in 2009, in 2010, passenger transportation density in expressway network rose by 2.25%.49.05% of passenger turnover volume was produced by mini-type buses(the seat amount of every bus is less than 8), and the volume rose by 1.79%.The average speed of Ⅰ-type bus rose by 0.68%, while the speeds of Ⅱ-type, Ⅲ-type and Ⅳ-type buses decreased by 0.26%, 1.70% and 1.73% respectively.Freight transportation density rose by 13.32%, and 80.95% of freight turnover volume was produced by tractor-trailer vehicles.The percentage of empty to loaded truck kilometers of trucks was 20.05% and rose by 0.21%.According to the standard of GB 1589—2004, the percentage of trucks with the overweights more than 30% is 4.85%.The transportation of Chinese expressway network kept continuous high-speed growth in 2010.More>
2011, 11(6): 68-73. doi: 10.19818/j.cnki.1671-1637.2011.06.011
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Optimization model of short-distance liner ship route based on tripartite game
CHEN Kang, YANG Zhong-zhen
Abstract: Government subsidy, carbon emission control, shippers' choices of transport modes were considered, the optimization model of short-distance liner ship route was developed based on tripartite game relations among carriers, shippers and government. The model could not only optimize the fleet deployment and structure design of ship route simultaneously, but also work out the reasonable amount of government subsidy by using user equilibrium principle. A genetic algorithm based on time-space network expansion and Frank-Wolf algorithm was developed to solve the model, and short-distance liner ship routes in the western area of Bohai Bay were optimized. Analysis result shows that when pendulum-pattern route among major ports in the western area of Bohai Bay is deployed with 9 ro-ro ships of 40 000 t, and government subsidy is 1 121.28 yuan · d-1, the total benefit of per ship is 704 567.12 yuan· d-1, carbon emission reduces by about 17.78%. When carbon emission is expected to decrease by more than 20%, circle-pattern route is deployed with 8 ro-ro ships of 40 000 t, the route can bring total benefit of 956 264.83 yuan · d-1 for carriers, reduce carbon emission by about 27.23%, but government subsidy reaches up to 56 075.26 yuan· d-1. The calculating result accords with the expectation result, so the optimization model is effective.More>
2011, 11(6): 74-81, 88. doi: 10.19818/j.cnki.1671-1637.2011.06.012
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Determining method of service scope for logistics park
SUN Bao-feng, LUO Qing-yu, XU Peng, ZHENG Yang
Abstract: Competition relationships among several logistics parks and the selection demand of customer on a certain logistics park were considered.The lack of present method solving the service scope problem of logistics park was analyzed.The step-divided determining method fused with breaking point model and Huff probability model was presented for service scope of logistics park.On the basis of DEMATEL method, the improved breaking point model was utilized to analyze and choose the key factors with high influence on the service scope of logistics park, and initial space service scope was obtained.By using the improved Huff probability model, rational threshold values were identified, and initial space service scope was modified.Analysis result shows that the key factors with high influence on the service scope of logistics park are government supporting to logistics industry, logistics demand of customer, development level of region economy, scale of logistics park and service level of customer respectively.By using the method, the per unit area turnover and logistics strength of logistics park are 10.25×104 yuan·km-2 and 8.39×104 t·km·km-2 respectively, while the values are 10.18×104 yuan·km-2 and 8.28×104 t·km·km-2 by using traditional method.So the determining method is effective.More>
2011, 11(6): 82-88. doi: 10.19818/j.cnki.1671-1637.2011.06.013
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Distribution project optimization of united transportation of railway and highway
XIE Hai-hong, LIU Ying
Abstract: To improve the customer satisfaction of logistic service and reduce the transportation cost in the united transportation of railway and highway, the paths among the distribution centers of railway logistics, freight transportation stations and customers were taken as optimal object, the distribution patterns of distribution centers of railway logistics were analyzed, a route choice model of logistic distribution with an objective function of the minimal distribution cost to customers was set up, and the unit transportation costs, storing costs and packaging costs of freights at all notes and the freight requirements of customers were considered.Computation result shows that the total cost of logistic transportation is minimal when customers receive freights from the stations rather than the centers, which indicates that the logistic distribution problem can be accurately depicted by using the model.More>
2011, 11(6): 89-93. doi: 10.19818/j.cnki.1671-1637.2011.06.014
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Analysis method for traffic safety of mountainous freeway tunnel groups
ZHANG Sheng-rui, LI Yun, ZHAO You-gong
Abstract: Vehicle speeds at different locations of a typical mountainous freeway tunnel group were analyzed by using police traffic radar and Metro Count 5600, the relationship function between the speeds and the locations was established, the change laws of the speeds were studied, and the risk levels at different locations was analyzed by computing the change rates of accelerations.Analysis result shows that at the entrances and the connection sections, the risk coefficient averages of cars and trucks in upward direction are 11.72 and 5.77 respectively.In downward direction, the averages are 19.71 and 8.53 respectively, so the risk levels are relatively higher.At other locations, the risk coefficients approximately equal to zero, so the risk levels are lower.In addition, the risk coefficients of cars are much higher than those of trucks.More>
2011, 11(6): 94-99. doi: 10.19818/j.cnki.1671-1637.2011.06.015
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CGE simulation of fuel oil tax impact on national economy and transportation
YUAN Zhang-wei, WANG Jian-wei, JIAO Ping
Abstract: In order transportation indu to simulate the influences of fuel oil stry, the fuel-transportation-economy tax reform on national economy and TSA-CGE model was built based on fuel, income and expense, trade, public welfare, social investment, and general equilibrium. A fuel oil tax program was set, which fuel consumption tax rate rised from 5% to 20%, and the influences of the program on macro-economy and transportation were simulated. Simulation result shows that fuel oil tax program can promote the developments of investment, residents' incomes, government savings, but have negative impact on economic aggregate growth, import and export. The program can cause the increases of rail transport, total urban traffic output, lead to the declines of other transport outputs, and the overall output prices of transport modes show a rising trend. The program can promote the decrease of domestic oil product demand, and improve the use efficiency of oil.More>
2011, 11(6): 100-105. doi: 10.19818/j.cnki.1671-1637.2011.06.016
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Traffic information engineering and control
Calculation method of central guidance path optimization
GONG Bo-wen, LIN Ci-yun, YANG Zhao-sheng, LI Jing
Abstract: Based on parallel calculation technology and network data storage method, traveler preferences were considered, the multi-level network decomposing method and the shortest path calculation method of deque were analyzed, and a new central guidance path optimization calculation method was put out. On the basis of the practical data of road networks in Changsha City and Changchun City, and tests on three different parallel calculation platforms including ordinary PC cluster, Lenovo server cluster and HP workstation cluster were carried out. Test result indicates that by using network data storage method, the storage locations of adjacency nodes and corresponding arcs can be determined directly, and the query time of node information obviously decreases. According to multi-level network decomposing method, the probability of main road as cutted arc reduces, and the commutation amounts of processors during the shortest path calculation process reduce. By using the shortest path calculation method of deque, the calculation speed of shortest path obviously increases. Through the new calculation method, the calculation time of 4 million shortest paths in Changsha City is 46 s, the calculation time of 11.7 million shortest paths in Changchun City is 72 s, and both of them satisfy the demand that central guidance path optimization time should be less than 5 rain.More>
2011, 11(6): 106-113, 126. doi: 10.19818/j.cnki.1671-1637.2011.06.017
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Optimal velocity difference model of non-neighboring vehicles
SUN Di-hua, ZHANG Jian-chang, LIAO Xiao-yong, TIAN Chuan, LI Yong-fu, LIU Wei-ning
Abstract: The optimal velocity model, generalized force model and full velocity difference model were described, and the deficiencies of these models solving traffic flow problem were analyzed.On the basis of full velocity difference model, the concern degree of driver on the optimial velocity difference information of two non-neighboring preceding vehicles was considered, and the optimal velocity difference model was put out.Through linear stability analysis, the stability condition of traffic flow was obtained.By using numerical simulation, optimal velocity difference model and full velocity difference model were compared.Simulation result shows that by using optimal velocity difference model, the sensitive coefficient of critical stability curve becomes smaller, free flow region increases obviously.While sensitive coefficient is 0.310 0 s-1, traffic flow stability strengthens, and the phenomenon of negative velocity does not appear.While sensitive coefficient is 0.777 8 s-1, and reaction coefficient is 0.2, vehicle velocities can basically maintain 0.963 5 m·s-1.With the increase of reaction coefficient, the produce hysteresis loops of velocities gradually tend to a point.So the optimal velocity difference model is effective.More>
2011, 11(6): 114-118. doi: 10.19818/j.cnki.1671-1637.2011.06.018
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System design of operation monitoring and health management for large passenger aircraft
MA Xiao-jun, ZUO Hong-fu, LIU Xin
Abstract: The research statuses of real-time operation monitoring and health management for large passenger aircraft were reviewed, the general frame of health management system for C919 aircraft was presented, and it was divided into three modules such as real-time monitoring, trend analysis and prediction of health condition, fault diagnosis and maintenance strategies.Six key technologies and methods of achieving the system were analyzed including real-time monitoring technology on ground, trend analysis and prediction method, remaining life prediction method, fault diagnosis algorithm, maintenance decision method, system validation and simulation technologies, and related researches and applications in this field were prospected.Analysis result shows that real-time operation monitoring for aircraft can reduce troubleshooting time, improve on-time performance and availability, and schedule flight easily.Health management for aircraft can help engineers effectively make maintenance tasks and control maintenance interval, implement preventive maintenance and condition-based maintenance, lower maintenance cost greatly, enhance reliability and economy, and provide improvement references for aircraft design.More>
2011, 11(6): 119-126. doi: 10.19818/j.cnki.1671-1637.2011.06.019
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