交通运输工程学报

Design method of no-fines porous concrete composition based on vibration compaction

HU Li-qun, SHA Ai-min, ZHANG Sha-sha

Abstract: The viscosity change rules of cement pastes, cement fly-ash pastes and cement silica fume pastes with different water to powder ratios were studied by using paste penetration test.Paste adhesive capacity to aggregate and paste leakage condition were analyzed based on mixture mixing test and vibration compaction test, and the design method of no-fines porous concrete composition at vibration compaction condition was provided.Analysis result indicates that in the mixing process of mixture, the amount of paste adhered to aggregate increases firstly and then decreases with the increase of paste penetration value, and paste adhesive ability is great when penetration value is 20-40 mm.Penetration value is further narrowed to 20-25 mm to avoid paste leakage and specimen damage at vibration compaction condition.No-fines porous concrete with 21.8% void ratio is designed by using the method, pore distribution in specimens is uniform, and 28 d compressive strength and flexural strength can reach 22.8 MPa and 3.4 MPa respectively.More>

2012, 12(2): 1-9. doi: 10.19818/j.cnki.1671-1637.2012.02.001

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Calculation method of horizontal surrounding rock pressure for tunnel

LUO Yan-bin, CHEN Jian-xun

Abstract: The deformation feature of middle wall for tunnel during construction was analyzed, the inner relationship between the deformation and the horizontal load was studied, and a new calculation method of horizontal surrounding rock pressure for tunnel was proposed.In the method, the analysis theory of structural mechanics was adopted to establish the relationship, in which the pressure was obtained by utilizing the monitoring deformations of middle wall.The pressure of V grade surrounding rock of shallow-buried soil tunnel in Tianhengshan is 110 kPa gained by the new method, and its range is 88-145 kPa gained by the Xie Jia-xiao method.When the friction angle of surrounding rock is 45° taken by the Xie Jia-xiao method, the pressure is 115 kPa and is close to the value computed by the new method, and their difference is 5 kPa, which proves that the new method is feasible.More>

2012, 12(2): 10-17. doi: 10.19818/j.cnki.1671-1637.2012.02.002

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Finite element model of flexible airport pavement structure for large aircraft

YOU Qing-long, LING Jian-ming, YUAN Jie, SHAO Dao-jie

Abstract: The finite element model of three-layer pavement structure was set up by using general finite element software ABAQUS.The influences of model geometry size, boundary conditions, contact conditions among layers, element types, and grid divisions on the mechanical responses of pavement structure were analyzed under large aircraft load.The parameters of flexible airport pavement structure's finite element model were put forward to adapt the characteristic of large aircraft load, and the effectiveness of the model was verified by using the measured mechanical response data.Study result indicates that considering the whole landing gear load of large aircraft, the geometry size of finite element model is appropriately 30 m×30 m×10 m, and the tie is chosen for completely continuous interaction among layers.C3D8R is used as an optimal element type, and the element size of load region could be controlled not to exceed 0.05 m×0.05 m.All the displacements are constrained at the bottom of the model, horizontal displacement is corresponded with the model constraint around, and the finite element model is effective verified by measured data.More>

2012, 12(2): 18-23. doi: 10.19818/j.cnki.1671-1637.2012.02.003

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Accelerated loading dynamic response of full-scale asphalt concrete pavement

GUAN Zhi-guang, ZHUANG Chuan-yi, LIN Ming-xing

Abstract: The dynamic response of pavement structure under moving vehicle loads was measured by using the accelerated loading test facility of full-scale asphalt concrete pavement.The dynamic strain at the bottom of surface layer for the pavement and the vertical compressive stress at the top of subgrade were taken as analysis objects, and the influences of axle load, speed and tire pressure on the dynamic response were studied.The regression models among dynamic response, axle load and speed were established respectively.Four kinds of pavement structures were tested in different axle loads, speeds and tire pressures.Analysis result shows that under moving vehicle loads, the strain response at the bottom of surface layer is in the alternative condition of tensile strain and compressive strain.Under intermediate test temperature, the strain response at the bottom of surface layer increases linearly with the increase of axle load, the vertical compressive stress at the top of subgrade shows uniaxial stressed state, and it increases with the increase of axle load.Speed affects the strain response at the bottom of surface layer significantly, but it has little influence on the vertical compressive stress, and affects the stress pulse duration only, and the stress pulse duration and strain response at the bottom of surface layer reduce with the increase of speed.The destroy degree of pavement is more serious in low speed and heavy load, but tire pressure has little influences on the strain at the bottom of surface layer and the vertical compressive stress at the top of subgrade.More>

2012, 12(2): 24-31. doi: 10.19818/j.cnki.1671-1637.2012.02.004

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Coupling vibration analysis of single-magnet suspension vehicle-bridge for maglev train

LIANG Xin, LUO Shi-hui, MA Wei-hua, WU Qing, XU Zi-qiang

Abstract: In order to study the coupling vibration of single-magnet suspension vehicle-bridge, suspension control system, vehicle structure, elastic track beam and bridge installation system were taken as a whole system, and maglev train suspension control-elastic bridge-mechanical structure vertical coupling vibration model of whole system was established.The effects of maglev train at different speeds on birdge were simulated by using external loads with different frequencies.The changes of mid-span deflection and vibration acceleration for different beam types were analyzed under the coupling condition of whole system.Study result shows that the mid-span deflection of simple-supported beam is about 2.5 times as the suspension position deflection of two-span-continuous beam when single-magnet suspension process achieves stable state.When train passes bridge at the speed of 200 km·h^-1, the deflection is slightly smaller than that at the case of 400 km·h^-1, the time that requires to achieve stable state for former case is about 1/3 of latter case.The mid-span deflection at suspension position for continuous beams is about 40% of the deflexion for simple-supported beam when train passes bridge at an identical speed, and the vibration acceleration of former case is smaller than that of latter case.The range of bridge critical mounting stiffness in simulation process is from 5.5×10⁷ N·m^-1 to 6.5×10⁷ N·m^-1, and the dynamics performance of two-span-continuous beam is better than that of simple-supported beam.More>

2012, 12(2): 32-37. doi: 10.19818/j.cnki.1671-1637.2012.02.005

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Numerical limit analysis of stability for bedding rock cutting slope

CHEN Peng, XU Bo-hou

Abstract: According to the key influencing factors of bedding rock cutting slope stability, the influences of slope height, load on the top of slope and engineering protection on the stability of bedding rock slope model with a group of the runned-through planes of weakness were studied by nonlinear FEM srength reduction method, and traditional limit equilibrium method was used for comparison and verification.Analysis result shows that when the slope grade is larger than rock obliquity, it is disadvantageous to slope stability, and safety coefficient decreases with the increase of slope height.When load is applied on the top of slope, the reduction of safety coefficient depends on the relative position between load and runned-through plastic zone.Retaining wall or anchor rod can increase slope safety coefficient by blocking and intercepting runned-through plastic zone, and plastic zone moves to other more weak structural plane, its moving direction depends on initial sustaining strength.The finite element calculation result of safety coefficient based on Drucker-Prager yield criterion is about 22% higher than the result of traditional limit equilibrium method based on Mohr-Coulomb criterion, it is very close to the research result of about 25% by Zheng Ying-ren, et al, so finite element srength reduction method is feasible.More>

2012, 12(2): 38-45. doi: 10.19818/j.cnki.1671-1637.2012.02.006

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Energy availability of active suspension without external energy supply

CHEN Shi-an, WANG Yong-gang, WANG Dong, HE Ren, LIU Hong-guang

Abstract: The absolute ratio of mean power reclaimed in the semi-active control mode divided by the value consumed in the active control mode was proposed as the evaluating index of energy availability for active suspension without external energy supply(ASWEES).The performance and energy availability of ASWEES were analyzed based on optimized PID and LQG controllers, which were designed for a quarter-heavy-vehicle ASWEES.When the damping ratio was 0.1, PID control parameters were optimized by using the genetic algorithm with suspension quadratic performance index taken as the objective function.It is pointed that the suspension quadratic performance index of ASWEES based on optimized PID control is 3.32% bigger than the index based on LQG control, and their energy availability indexes are 17.15 and 226.33 respectively.The result indicates that the performance of ASWEES based on LQG control is weakly better, two ASWEESs meet the demand of energy availability, and the energy availability of ASWEES based on LQG control is strongly better.More>

2012, 12(2): 46-52. doi: 10.19818/j.cnki.1671-1637.2012.02.007

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Estimation method of aeroengine pollution emissions

SUN Jian-zhong, ZUO Hong-fu, LIU Peng-peng, FU Yu

Abstract: On the basis of engine performance model, the effects of performance deterioration on engine pollution emissions, such as NO_x, CO, UHC and Soot, were studied, and an estimation method of total emissions in flight based on flight parameters and engine performance model was proposed.By fitting ICAO emission data, the reference emission indices of engine under ground condition were obtained, the emission indices in flight were calculated by using the reference emission model, and the total emissions in flight were calculated based on flight parameters and engine performance model.Study result shows that engine performance deterioration has great effects on the emission indices.When considering the impact of fuel flow, the performance deterioration has less impact on NO_x emission, but makes the total emissions of CO, UHC and Soot increase.For a modern turbo fan engine in a middle range flight, the total emission of NO_x is about 100 kg, CO about 20 kg, and both UHC and Soot less than 1 kg.Engine performance deterioration results in an increase of about 10% for the total emissions of CO, UHC and Soot, but about 2% for NO_x.More>

2012, 12(2): 53-61. doi: 10.19818/j.cnki.1671-1637.2012.02.008

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Augmented semi-virtual reality cockpit technology

TANG Yong, GU Hong-bin, LI Peng

Abstract: In order to enhance the visual sense of users and the interaction performance of human-cockpit system in the semi-virtual reality cockpit system, an augmented semi-virtual reality cockpit technolgy was presented, which incorporated a realistic view of hand into the virtual environments and made user see his own real hand in real time.The captured images by using camera were real-time segmented by skin color detecting algorithm.The segmented foreground images were rectified by using adaptive weighted stereo matching algorithm and view morphing algorithm.Hand images were seamlessly integrated into virtual environment by using virtual-real matching and virtual-real fusion methods, which can provide user with the visual images in augmented virtual environment.Experimental result shows that augmented semi-virtual reality cockpit technology make users feel true for the feedback of touch and vision.The smallest side length of the square clicked by users is 8 mm in head-mounted virtual environment.In augmented semi-virtual reality cockpit system, the average interaction time decreases by about 50% and 18% compared with traditional data glove method and semi-virtual reality method.The technolgy effectively improves the human-cockpit interaction performance of the system, enhances its practicability, and its developed cost decreases.1 tab, 11 figs, 22 refs.More>

2012, 12(2): 62-69. doi: 10.19818/j.cnki.1671-1637.2012.02.009

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Macroscopic econometrics model of traffic accident

WANG Jun-lei, SUN Xiao-duan, HE Yu-long, HOU Shu-zhan

Abstract: From the points of macroscopic factors such as economic development level, population number, vehicle ownership and road condition, the regularities of traffic accidents at home and abroad were analyzed.The relations among per capita GDP and vehicle ownership per 1 000 population, mortality per 10 000 vehicles, mortality per 100 000 population were studied.Based on macroscopic econometrics and Cobb-Douglas function, the panel data model of traffic accident was set up by using the historical data in seven countries.Fixed effect model and random effect model were used to estimate parameters respectively, Hausman test was carried out, and the macroscopic econometrics models of traffic accidents for the seven countries were set up.Calculation result shows that among the parameters of traffic accidents, mortality per 100 000 population is negative correlation with per capita GDP and per capita road length, mortality per 100 000 population is positive correlation with vehicle ownership per 1 000 population.Through Hausman test, chi-square distribution value is 3.91 when freedom is 3, the probability is 0.02 and less than the confidence level which is 0.05.Compared with the random effect model, all the confidence levels of variables for fixed effect model are less than 0.05, and the goodness of fit is better.So the fixed effect model is effective.More>

2012, 12(2): 70-75. doi: 10.19818/j.cnki.1671-1637.2012.02.010

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Nested logit model of combined selection for travel mode and departure time

YANG Li-ya, SHAO Chun-fu, HAGHANI A

Abstract: Based on the maximum random utility theory, traveler characteristic, travel characteristic and the service level of travel mode were taken as utility variables, travel mode and departure time were taken as alternative parts, and two nested logit(NL) models were built, one structure with departure time located in lower layer and another structure with travel mode located in lower layer.The sample data of resident travel in Beijing City were analyzed, and the travel behavior changes of car travelers were simulated when different car travel costs were charged in morning peak period.Calculation result shows that compared with traditional MNL model, there is better statistic characteristic in NL model.After adjustment, the goodness of fit increases from 0.338 to 0.404.In the two NL models, the structure with departure time located in lower layer has stronger adaptability on sample data than the structure with travel mode located in lower layer.While car travel cost in morning peak period is 5 yuan, 72.6% of car travelers will still insist on original travel mode and departure time, 22.4% of car travelers will still insist on original travel mode, but will change departure times, 4.8% of car travelers will turn to public transit, but will still insist on original departure time, and only 0.2% of car travelers will change travel mode and departure time simultaneously.While car travel cost in morning peak period is 10 yuan, 51.7% of car travelers will still insist on original travel mode and departure time, 40.4% of car traveler will still insist on original travel mode, but will change departure times, and only 7.9% of car travelers will turn to public transit, but will still insist on original departure time.While car travel cost in morning peak period is 20 yuan, 27.5% of car travelers will still insist on original travel mode and departure time, 60.6% of car travelers will still insist on original travel mode, but will change departure times, and only 11.9% of car travelers will turn to public transit, but will still insist on original departure time.More>

2012, 12(2): 76-83. doi: 10.19818/j.cnki.1671-1637.2012.02.011

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Forecasting and early-warning model of port traffic resource carrying capacity

JIAO Yu, KANG Yu-tao, YIN Xiao-bei, WANG Jin-hui, XU Le-ping

Abstract: Based on the calculation method of channel traffic capacity, the static carrying capacity model of channel resource was set up.According to the computing method of anchorage scale and basic judgment parameter, the classification model of anchorage resource carrying capacity was put forward.On the basis of queuing theory, the service strength of port berth and the carrying capacity models of channel resource and anchorage resource were fused, the comprehensive forecasting and early-warning model of port traffic resource carrying capacity was built, and example verification was carried out through case port in Southern China.Calculation result shows that by using the proposed model, channel resource carrying capacity indexes in 2008 and 2010 are 0.405 and 0.608 respectively, comprehensive anchorage resource carrying capacity indexes in 2008 and 2010 are 1.489 and 0.600 respectively, the service strength of port berth in 2008 is 0.565, and the calculation results are consistent with the fact.With the increase speed of cargo throughput, the minimum and maximum of channel resource carrying capacity indexes will be 0.593 and 0.796 respectively in 2015, and will be 0.685 and 0.944 respectively in 2020.Based on the existing anchorage resource, while water depth is below 5 m, the maximum anchorage resource carrying capacity indexes will be 0.177 and 0.210 respectively in 2015 and 2020.While water depth is from 5 m to 10 m, the maximum anchorage resource carrying capacity indexes will be 1.037 and 1.231 respectively in 2015 and 2020.While water depth is more than 10 m, the maximum anchorage resource carrying capacity indexes will be 1.294 and 1.535 respectively in 2015 and 2020.The minimum service strengths of port berths will be 0.858 and 0.994 respectively in 2015 and 2020.More>

2012, 12(2): 84-92. doi: 10.19818/j.cnki.1671-1637.2012.02.012

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Temporal-spatial analysis model of traffic accident frequency on expressway

MA Zhuang-lin, SHAO Chun-fu, HU Da-wei, MA She-qiang

Abstract: In order to analyze the relationships among traffic accident frequency and potential influencing factors such as time, road space structure and traffic running environment, nine independent variables were selected from the aspects of time and space, two kinds of section divided methods were adopted, which were fixed-length consistent segment and longitudinal grade consistent segment, and the hourly, weekly and monthly distribution models of traffic accident frequency were constructed.A typical accident-prone section was selected, and Poisson regression model, negative binomial regression model, zero-inflated Poisson regression model and zero-inflated negative binomial regression model were used to fit hourly, weekly and monthly distribution models respectively.The best forms of three models were determined, and the temporal-spatial analysis model of traffic accident frequency was established based on the goodness of fit test.Analysis result shows that the fitting effect of negative binomial regression model is better for traffic accident hourly and monthly distribution models based on fixed-length consistent segment from the views of AIC and BIC, and the fitting effect of Poisson regression model is better for other models.The prediction errors of traffic accident hourly, weekly and monthly distribution model based on fixed-length consistent segment are less than those of longitudinal grade consistent segment.4 tabs, 15 refs.More>

2012, 12(2): 93-99. doi: 10.19818/j.cnki.1671-1637.2012.02.013

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Route choice model with preferences in traffic network

CHEN Jing-rong, XU Rui-hua

Abstract: In urban traffic network, when the attributes of times and costs for paths were confirmed, the path selection problems with the preferences of travelers or not were analyzed.When there were no preferences, the integrated attribute value of each path was obtained by using the information entropy theory and the multi-attribute synthetic decision method.When the preferences for different paths were given by using the reciprocal judgment matrixes, for obtaining the weight of each attribute, an optimal model of weight vectors was set up to minimize the deviations between the reciprocal judgment matrixes.The model was solved by the analytic method, the attribute weights were used to calculate the integrated values of the paths, and the path with the maximum was the optimal.Analysis result shows that for the no preference problem, path 2 is the optimal with the integrated value 0.918.Otherwise, for the preference problem, path 4 is the optimal with the integrated value 0.965.Under the two conditions, the orders of six chosen paths are different.So, the preferences of travelers have obvious effect on route choice.More>

2012, 12(2): 100-104. doi: 10.19818/j.cnki.1671-1637.2012.02.014

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K-nearest neighbor model of short-term traffic flow forecast

YU Bin, WU Shan-hua, WANG Ming-hua, ZHAO Zhi-hong

Abstract: In order to accurately forecast the short-term traffic flow, a K-nearest neighbor(K-NN) model was set up.The time and space parameters of the K-NN model were analyzed.Based on four different combinations of state vectors, the time dimension model, upstream section-time dimension model, downstream section-time dimension model and space-time dimension model were proposed.The four different models were validated by using the GPS data from taxis of Guiyang.Analysis result indicates that the K-NN model with both space and time parameters has highest forecasting precision than the other three models, and its average prediction error is about 7.26%.The distance measuring mode with exponent weight has higher accuracy in choosing the nearest neighbors, and its average prediction error is about 5.57%.The predicting performance of improved K-NN model with exponent weight and space-time parameters is best compared with the artificial neural network model and the historical average model, and its average prediction error is only 9.43%.So the improved K-NN model is an effective way for forecasting short-term traffic flow.More>

2012, 12(2): 105-111. doi: 10.19818/j.cnki.1671-1637.2012.02.015

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Petri net model of maglev train running across different control systems

ZHENG Wei

Abstract: The general framework of running control system on maglev train was studied according to the running requirements of maglev train running across different control systems.Functional subsystems need to be added was defined.The hierarchical models of system key attributes, maglev operation procedures and the subsystem function were built based on the system theory by using Petri net.The key attributes of whole system were described by the highest model, and the operation procedures of maglev train and the reliabilities of subsystems were presented in the lower level model.The relationship between the failure rates of maglev train running across different control systems and the reliabilities of subsystem components was quantitatively analyzed with the model.It is pointed that the loss ratio of network connecting neibouring control systems should be lower than 10^-6 times per hour when the required failure number of maglev train running across different systems is no more than 1 time per year.The failure rates of maglev train running across different control systems are 1.95×10^-5 and 1.65×10^-5 times per hour when the triggering times equal 0.2 and 2.0 min respectively, and the stepping times equal 4 and 16 min respectively.Simulation result shows that the failure rates of train running across the boundary decrease when the reliabilities of a and b networks are improved, or the triggering time and stepping time of train are prolonged.The reliability requirements of subsystem components based on the required key attributes of system level are quantantatively identified by using the proposed approach.More>

2012, 12(2): 112-118. doi: 10.19818/j.cnki.1671-1637.2012.02.016

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Running conflict mechanism of high-speed railway tarin

WEN Chao, PENG Qi-yuan, CHEN Yu-hong

Abstract: During the running process of high-speed railway train, the distribution regularity and cumulative process of random interference were analyzed.The status deviation map of running plan was used, and the change mechanism of running delay for high-speed railway train was described.During the running process of high-speed railway train, the distribution regularity and utilization process of redundancy time were analyzed.The status recovery map of running plan was used, and the process that redundancy time assimilated delay time was described.Based on the interacting process of running interference and utilization process of redundancy time, the generation mechanism of running conflict for high-speed railway train was studied, and the recurrent process of running status for high-speed railway train under the interaction of random interference and redundancy time was set up.The simulation system of running interference, redundancy time and conflict was developed by Yi language.While interference probabilities were 50% and 30% respectively and redundancy time proportions were 15% and 10% respectively, the generation mechanisms of running conflict for high-speed railway train under 4 conditions were simulated.Simulation result indicates that random interference can lead to the generation of running conflict, and redundancy time can absorb delay and reduce conflict numbers.The smaller random interference is, the fewer running conflict is.When interference probability reduces by 20%, the running conflict number reduces by 17.3%.The bigger delay is, the larger available redundancy time is.When the proportion of redundancy time increases by 5%, the coefficient of conflict absorption increases by 6.5%.The redundancy time plays more obvious role on absorbing running conflict when there are little interference probability and small total interference.More>

2012, 12(2): 119-126. doi: 10.19818/j.cnki.1671-1637.2012.02.017

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