交通运输工程学报

Engineering characteristics of plate-like saline soil in Xinjiang

FENG Zhong-ju, LI Wei-zhou, WANG Ting-wu, LIU Xiao-fei, CHENG Chao

Abstract: The engineering characteristics of plate-like saline soil were analysed on the basis of laboratory particle size analysis test, water content (mass percentage) limit test, compaction test, strength test, deformation test and swelling test.Analysis result shows that plate-like saline soil is mainly made up of gravelly soil and has different gradations resulted from sampling locations.The ranges of plasticity index, maximum dry density and optimum moisture content are 0.57~3.20, 2.22~2.25 g·cm-3 and 5.7%~6.2% respectively.Under natural condition, its maximum unconfined compressive strength is 28.6 MPa, and it has the characteristics of rocks and belongs to rock salt.Plate-like saline soil has low compressibility and meets the deformation index requirement of highway subgrade.Under the change of water and heat environment, with the increase of salinity, the coefficient of collapsibility and salt-expansion stress increase, and the salt-expansion temperature reaches ahead of time as the sodium sulfate content increases.Salt expansion can be controlled by vehicle load, which reduces the engineering disease resulted from salt expansion.More>

2010, 10(6): 1-8. doi: 10.19818/j.cnki.1671-1637.2010.06.001

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Design method of asphalt mixture aggregate gradation based on high-temperature performance

LI Ping, WANG Bing-gang, ZHANG Zheng-qi

Abstract: In order to gain the aggregate gradation with extrusion, density and stabilization, the density test of coarse aggregate was used to research the influences of vessel volume and spreading mode on aggregate density, penetration test was established based on MTS, and Hamburg wheel rutting test was taken for different mixtures. The gradation of coarse aggregate was confirmed by penetration test, and the aggregate gradations of asphalt mixtures were combined by Bailey method. Test result shows that because of the difference of vessel volumes and falling modes of aggregate, the home and abroad test difference of loose densities of aggregate is 6%. The good high-temperature performance of the mixture designed with Bailey method can not be assured. Penetration test can distinguish the stability of coarse aggregate effectively, and the correlation coefficient with the rutting depth of mixture is 0.71. So the high-temperature performance of mixture can be kept well by using the method.More>

2010, 10(6): 9-14. doi: 10.19818/j.cnki.1671-1637.2010.06.002

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Effect of magnesium sulfate solution on frost resistance of concrete under stress condition

ZHANG Yun-qing, YU Hong-fa, SUN Wei, LIU Jun-long, ZHANG Jian-ye

Abstract: The frost resistances of three kinds of concretes under flexural stress subjected to water and 5% MgSO₄ (mass fraction) solution were studied by using accelerated freezing-thawing method. The considered concretes include high strength concrete (HSC) added with 20% fly ash (20% of binder mass), high-volume mineral admixture concrete (HVMAC) added with 40% fly ash, 10% slag and 5% silica fume, and high durable concrete (HDC) added with high-volume mineral admixture, air-entraining agent, superplasticizer, fibres and expansion agent. Third point loading method was applied on the specimens in the process of freezing-thawing cycle, and the enacted flexural stress was 35% of failure stress. Analysis result shows that the frost resistances of HSC and HDC respectively increase 46 times and more than 70% under flexural stress subjected to MgSO₄ solution as compared with water, and their anti-freezing-thawing cycles are respectively more than 425 times and 900 times. But the frost resistance of HVMAC decreases by 67% under flexural stress, and its anti-freezing-thawing cycles are only 75 times.More>

2010, 10(6): 15-19. doi: 10.19818/j.cnki.1671-1637.2010.06.003

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Finite element analysis of asphalt pavement on long-steep longitudinal slope

YANG Jun, LI Wei-nong, CHEN Zhi-wei, YU Bin

Abstract: Because the rutting damages of asphalt pavement easily appeared at uphill sections of long-steep longitudinal slope, five different slopes were chosen based on the visco-elastic constitutive model of asphalt mixture, and the distribution regularities of the maximum shear stress and vertical strain for mixture surface course under the action of standard axle load were analyzed by finite element software ABAQUS. The impacts of traffic load and vehicle speed on road sections with and without slopes were also presented. Calculation result indicates that maximum shear stress and vertical strain are directly proportional to slope and traffic load and inversely proportional to speed. Road sections with slopes are more sensitive to traffic load and speed. The average values of the maximum shear stress and vertical strain in the middle layer, which ranges from 4~10 cm below road surface, are greater than that of other layers. So the rutting damages are most likely to appear in the middle layer, and it is more important to improve the rutting resistance of middle layer for long-steep longitudinal slope.More>

2010, 10(6): 20-24. doi: 10.19818/j.cnki.1671-1637.2010.06.004

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Differentia settlement of widening subgrade for expressway

FU Zhen, WANG Xuan-cang, LI Hong-zhi, SHI Jian-ping, LIAO Zhi-gao

Abstract: Anxin widening expressway was taken as engineering background, centrifugal model test was applied, several geosynthetics material reinforcement proposals dominated by using geocell were forecasted and contrasted, and the settlements of old subgrade and widening subgrade were analyzed. Test result shows that the settlements during construction account for quite great proportion in half a year for old and new subgrades, above 70%. The settlement of reinforced subgrade is smaller than that of unreinforced subgrade, and the biggest and smallest settlements of various plans occur at the edge of new shoulder and the center of old subgrade. Because of good geology condition, the overall settlement is not certainly big, and there are no obvious differences of settlements among reinforced plans, maintaining at very small level. The smallest and biggest subsidence values are 1.67 cm and 3.33 cm respectively, and the biggest unequal settlement is 1.66 cm. Obviously, reinforce can balance the differentia settlement of subgrade, and reduce total ground settlement to a certain degree.More>

2010, 10(6): 25-31. doi: 10.19818/j.cnki.1671-1637.2010.06.005

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Flexural behavior experiment of reinforced concrete T-beams with steel plate-concrete composite strengthening

WANG Chun-sheng, YUAN Zhuo-ya, GUO Xiao-yu, GAO Shan, REN Teng-xian

Abstract: The flexural behaviors and failure modes of four reinforced concrete T-beams with steel plate-concrete composite strengthening were investigated. The major design parameters included damage level and bar-planted space. The loads, deflections, strains, cracks of test T-beams, the slippages between new and existing concretes, and the slippages between steel plates and new concretes were respectively measured by using load, deformation sensors and strain gauges. The ultimate bending capacities of test T-beams were simulated by using finite element software ANSYS, and were analyzed by using plastic method. The simulation values, theoretical calculation values and test values were compared. Comparison result shows that the ultimate bending capacities of the T-beams increase by two times. The influence degrees of damage levels and bar-planted spaces on the ultimate bending capacities are about 4%. The longitudinal slippages between the original and new concretes increase with the increments of bar-planted spaces. The maximal absolute differences among the simulation values, theoretical calculation values and test values are 9%, so steel plate-concrete composite strengthening method is feasible.More>

2010, 10(6): 32-40. doi: 10.19818/j.cnki.1671-1637.2010.06.006

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Influence of gravity center height on running safety of loaded double-stack container car

LANG Mao-xiang, PENG Yong-zhao, LIU Chun-qi

Abstract: According to the system dynamics of rigid bodys, the dynamics simulation models of single-vehicle and four-vehicle double-stack container cars under certain loading and running conditions were established by SIMPACK. Based on the evaluating criterias and indexes of railway train running safety, the simulation result was compared with experiment data. The relationship between the height of loaded car's gravity center and the running safety of double-stack container car was analyzed, and the reasonable height of gravity center was presented. Simulation result indicates that lateral wheelset force, wheel unloading rate and derailment coefficient increase with the increase of the height, and derailment coefficient firstly reaches its limit value. The limit value of the height is 2 480 mm under the most unfavorable loading condition.More>

2010, 10(6): 41-47. doi: 10.19818/j.cnki.1671-1637.2010.06.007

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Estimating method of pollution emissions for scheduled flight in different phases

WEI Zhi-qiang, WANG Chao

Abstract: ICAO standard emission model was analyzed. The equations of parameters, such as flight time, thrust, fuel flow and so on, were induced. Flight time and fuel flow could be replaced by the equations in the model. The influence of atmosphere and flight parameters was considered, the calibrated emission index models of various pollutes were introduced, and the emission parameters in different flight phases were calculated. As the flight example of B737-800 from Xi'an to Yantai, the pollution emissions were calculated by Delphi on VEATE, and the variation rules of pollution emissions were analyzed. The result shows that the emissions of CO₂ and NO_x mainly appear in cruise phase, and the emissions of CO and HC occur in taxiing phase. The emissions of the four pollutes above are CO₂, NO_x, CO and HC in the decreasing sequence. The absolute errors between the calculation values and the reference values of ICAO are less than 1%.More>

2010, 10(6): 48-52. doi: 10.19818/j.cnki.1671-1637.2010.06.008

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Tentacle algorithm of obstacle avoidence and autonomous driving for intelligent vehicle

NIU Run-xin, XIA Jing-ting, WANG Xiao-hua, MEI Tao

Abstract: Obstacle map was established by using velodyne radar. Tentacle regeneration, autonomous driving and avoiding obstacle strategy were analyzed. The influence of sideslip angle on tentacle regeneration was considered. INS (inertial navigation system) sensors with GPS were integrated by Kalman filter, and the longitudinal velocity and lateral velocity of vehicle were obtained. Therefore, tentacle regeneration method corresponding to specific "speed sets" based on sideslip angle identification was promoted. At low-medium speed, trajectory error reduces from 0.40 m to 0.20 m. At high speed, because of using good-performance controller and appropriate fusion parameters, trajectory error reduces from 1.00 m to 0.75 m. Analysis result indicates that the promoted method effectively ensures obstacle avoidence and autonomous driving.More>

2010, 10(6): 53-58. doi: 10.19818/j.cnki.1671-1637.2010.06.009

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Analysis method of braking performance for multi-axle automobile

HE Ren, TONG Cheng-qian, HE Jian-qing, SHI Bing-liang

Abstract: According to ECE brabing regulation, the requirements of braking force distribution of multi-axle automobile were analyzed, the defects of analysis methods on the braking performance of multi-axle automobile were pointed out, and a method named adhesion utilization coefficient diagram was proposed. The adhesion utilization curves of all axles and the boundary curves requested by ECE braking regulation were painted in the same coordinate system, the relationships among the adhesion utilization coefficients and the boundary curves, and the braking performance of automobile were studied. Because the transfer of multi-axle automobile' vertical axle loads was larger when braking, when calculating the normal reaction forces from ground to wheels, a model was adopted, in which the loads on and below suspension were calculated separately. An example was cited to illustrate the application of the analysis method. The result indicates that when adhesion utilization coefficient is from 0.20 to 0.80, automobile has a high adhesion utilization efficiency. When braking strength is from 0.15 to 0.30, wheel lock sequence is front, middle and rear, which accords with wheel lock requirements, and the directional stability of automobile is guaranteed when braking. Obviously, the method is simple, practical and beneficial.More>

2010, 10(6): 59-63. doi: 10.19818/j.cnki.1671-1637.2010.06.010

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Situation and strategy planning of public transit priority development

XU Ya-hua, FENG Li-guang

Abstract: The service capacity, service quality, basic facilities construction of urban public transit and the development situation of city-countryside passenger transportation were analyzed. The five demand factors of urban public transit priority development were studied, including the rapid development of social economics, fast urbanization, fast motorization, constructing resources economization and environment friendship society, constructing modern comprehensive transportation system and meeting resident trip demands. Public transit priority development strategies were put forward, including perfecting law and regulation system, strengthening finance support, establishing standard subsidy system, establishing scientific ticket price system, conforming enterprise's operation management and promoting integration development of city-countryside passenger transportation.More>

2010, 10(6): 64-68. doi: 10.19818/j.cnki.1671-1637.2010.06.011

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Calculating method of carrying capacity for railway station bottleneck

TANG Bo, LEI Ding-you, ZHANG Ying-gui, WANG Xin-yu

Abstract: In order to calculate the carrying capacity of railway station bottleneck efficiently, a new kind of calculating method with 5 steps was put forward. The method took station bottlenecks' routes as object and the projection of routes' holding time under saturation condition as core. A polynomial equation of higher degree with an unknown variable was deduced by applying probability theory, and the equation could calibrate the key parameters in the calculating method. Algorithms for searching complete sub-graphs based on parallel-route relation graph were devised in order to determine the equation coefficients. Guangzhou orientation bottleneck in Dongguan Station was as a calculation example. Calculation result shows that the carrying capacity of the station bottleneck is 503 trains, 43^#, 45^# and 53^# turnouts are taken up by 102 trains, and the carrying capacity utilization ratio is 75%. So the calculating method has good maneuverability.More>

2010, 10(6): 69-74. doi: 10.19818/j.cnki.1671-1637.2010.06.012

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Prediction model of passenger transport volume in metropolitan region based on support vector machine

CHEN Li, MA Rong-guo

Abstract: The sample data set of metropolitan region's passenger transport volume was divided into training set, testing set and examining set, the loss function's parameters and penalty factor were determined according to the final prediction error criterion, the ε-insensitive loss function and the Gaussian kernel function were chosen to decrease prediction complexity, and a prediction model of metropolitan region's passenger transport volume was proposed based on support vector machine. The passenger transport volume of Beijing-Tianjin-Hebei Metropolitan Region was predicted by gradual changing the parameter values of loss function, penalty factor and Gaussian kernel function. Prediction result shows that the average relative error is 0.15%, and the total changing trends of prediction value and testing value are same, so the model is credible.More>

2010, 10(6): 75-81. doi: 10.19818/j.cnki.1671-1637.2010.06.013

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Analysis of pavement traffic volume using pass-to-coverage ratio

WU Ai-hong, CAI Liang-cai, GU Qiang-kang, WANG Hai-fu, YANG Fei, CHEN Yang

Abstract: The reason was analyzed that the repetition times of axle load were larger resulted from the coefficient of wheel tracking transverse distribution, the concept of pass-to-coverage ratio was introduced, and the calculation method of pass-to-coverage ratio was given in accordance with wheel tracking following normal distribution. The calculating method of effective tire width on flexible or rigid pavement was put forward, and the effect of stress or strain peak value on pass-to-coverage ratio was analyzed under the action of axle load. Taking heavy truck J6 and Delong 3000 acting on rigid pavement for example, single and mixture traffic volumes were calculated by using the method of pass-to-coverage ratio. Analysis result shows that the calculating result of axle load repetition times is right at peak value position under present specifications, but it reduces quickly away from peak value position. For single-axle double-wheel load of J6, the repetition times of axle load reduce by 50% under single traffic volume while loading position is 0.8 m away from peak value position. So the calculation method is more precise than present method.More>

2010, 10(6): 82-87. doi: 10.19818/j.cnki.1671-1637.2010.06.014

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Optimization model of fuzzy location-routing problem for searching trapped personnels in flood disaster

LI Shou-ying, MA Zu-jun, ZHENG Bin

Abstract: For ensuring the search-and-rescue effect of trapped personnel in flood disaster, the characteristics of rescue process were analyzed, an optimization model of location-routing problem (LRP) with time windows and fuzzy rescue time was established, and a genetic algorithm was introduced. The algorithm used three-segment real-code and designed matching crossover and mutation operations, and a replacement operation was added in the iterative process to accelerate convergence. A numerical example was given to validate the model and the algorithm. Analysis result shows that the average running time of ten times is 42.95 s when a MATLAB program is designed to realize the algorithm, and the deviations of the worst and the best to the average value are 1.56% and 3.48% respectively. So the algorithm is efficient, convergent and stable, and the model is feasible.More>

2010, 10(6): 88-93. doi: 10.19818/j.cnki.1671-1637.2010.06.015

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Optimum congestion pricing model of stochastic system with multiple user classes

ZHONG Shao-peng, DENG Wei

Abstract: Traffic network equilibrium model and marginal cost pricing (MCP) theory were combined, an optimum congestion pricing model of stochastic system with multiple user classes under the endogenous market share of advanced traveller information systems (ATIS) and demand elasticity was established, and the influences of the joint implementation of ATIS and MCP on different users' travel behaviours were analyzed. Analysis result indicates that MCP models with symmetric impedance function neglect external costs that travellers impose on users on nearby roads, and the obtained MCP is smaller than the real value. When the parameters of travel cost perception variations for equipped and unequipped ATIS users are 0.50 and 0.01 respectively, compared to none of traffic management measures being taken, the joint implementation of ATIS and MCP can save 14.3% of total network travel cost, and the separate implementation of ATIS or MCP can save 13.6% or 6.3% of total network travel cost respectively. So network operation performance can be optimized efficiently by the joint implementation of the two technologies.More>

2010, 10(6): 94-101. doi: 10.19818/j.cnki.1671-1637.2010.06.016

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Negotiation mechanism model of relationship between residential location and traffic system

ZHANG Lin, DU Wen, GUO Qian-qian

Abstract: In order to test the relationship between traffic and activity place, a negotiation model between homeowner and mobile home was proposed, and Nash equilibrium price of each housing price for city district was got and proven. The candidate cell set was received by fuzzy effectiveness estimation, and a mixed strategy of non-cooperative game was adopted in the candidate cell set. The existence of balanced solution was proposed to choose residential location about mixed strategy negotiation mechanism. A function was constructed, and the existence of balanced solution was proven by Brouwer fixed point theorem. An algorithm was proposed to solve the negotiation model. Numerical example result indicates that the mobile home number of choosing district 8 changes from 0 to 446 for 5 and B commute destinations, and the mobile home number of choosing district 9 changes from 460 to 601 for A and B commute destinations after the improvement of road 5-8. So traffic improvement affects residential choice, and the negotiation model is effective.More>

2010, 10(6): 102-110. doi: 10.19818/j.cnki.1671-1637.2010.06.017

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Automatic identification algorithm of train track occupancy

CAI Bo-gen, YAN Xi-hui, WANG Jian, SHANGGUAN Wei

Abstract: In order to resolve the automatic identification problems of train track occupancy at turnouts and on parallel sections, a new automatic identification algorithm was proposed based on LTS-Hausdorff distance and D-S evidence theory. The reference template of track LTS-Hausdorff distance was established, the calculation process of LTS-Hausdorff distance and the decision method of automatic identification were analyzed, and the effects of train speed and search threshold on the algorithm were studied. Test result shows that when there are 10 track points, the results of the new algorithm and the maximum likelihood track identification decision are same. The higher train speed is, the less track points are, and the algorithm is still effective. The smaller search threshold is, the shorter the algorithm realizing time is. So the algorithm is valid.More>

2010, 10(6): 111-115. doi: 10.19818/j.cnki.1671-1637.2010.06.018

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Signal timing optimization at isolated intersections under random condition

LU Bin, NIU Hui-min

Abstract: The stochastic characteristic of traffic flow was analyzed at isolated intersection, the deviation of queue length of phase vehicles correlating to the expected queue length was studied, the weights of all phases were considered, and an optimization model of signal timing was proposed. The quantitative relationships among phase clearance reliability (PCR), signal cycle and green time were determined, a deterministic transformation was achieved for the model, and a simulation example of two-phase signalized intersection was analyzed by using the model. The result indicates that when the variance of arrival rate increases from 0 to 350 pcu·s^-1, the cycle length increases from 50 s to 232 s, and the phase with the larger variance of arrival rate needs much green time. When the queue length increases from 4 pcu to 30 pcu, the phase clearance reliability only increases from 0.712 to 0.884. The random variation of arrival rate has an obvious effect on traffic signal setting, and the model is correct.More>

2010, 10(6): 116-120. doi: 10.19818/j.cnki.1671-1637.2010.06.019

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Delay models of right-turning vehicle crossing through pedestrian flow

HAN Yin, ZHANG Nan, MA Wan-da, CHI Yu-pin

Abstract: Based on the different characteristics of stochastic and congestion dispersing processes for pedestrian flows, two kinds of right-turning vehicle's delay models were defined by using stochastic distribution theory, and the delay characteristics during vehicle crossing pedestrian flow were analyzed. The crossing process of right-turning vehicle was simulated by using Vissim software, and the simulation delay value was compared with that of the delay models. Analysis result shows that when the length of pedestrian congestion dispersing time is 10 s, the length of pedestrian stochastic dispersing time is 15 s, each interval between pedestrians is 5 s, and pedestrian flow reaches 1 100 persons per hour, the deviation of the delay models is only 0.2 s, so the models are feasible.More>

2010, 10(6): 121-126. doi: 10.19818/j.cnki.1671-1637.2010.06.020

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2010 Vol. 10, No. 6

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