交通运输工程学报

Influence of direct coal liquefaction residue on viscoelastic properties of asphalt mortar

JI Jie, SHI Yue-feng, SUO Zhi, YAO Hui, XU Shi-fa

Abstract: SK-90 was taken as base asphalt, filler-asphalt ratio was 1.0, the direct coal liquefaction residue(DCLR)modified asphalt mortars with the DCLR contents as 5%, 10%, 15%, 20% and SK-90 asphalt mortar were produced respectively.The influences of DCLR on asphalt mortar rut factor, fatigue factor, creep stiffness modulus and creep rate were compared by dynamic shear rheometer(DSR)and bending beam rheometer(BBR)tests.The influence rule of DCLR on the viscoelastic properties of asphalt mortar was analyzed.Test result indicates that DCLR can significantly improve the high-temperature properties of asphalt mortar, reduce its lowtemperature and fatigue properties.DCLR also increases the elastic properties of asphalt mortar at high temperature and the viscous properties at low temperature.The high-temperature, lowtemperature and fatigue properties of asphalt mortar with high DCLR content are very sensitive to temperature.With the increase of DCLR content, the application scopes of asphalt and asphaltmortar become more and more narrow.Therefore, in the view of application, the content of DCLR is recommended to be less than 10%, and the asphalt and asphalt mortar can be applied for middle surface layer of asphalt pavement.More>

2015, 15(4): 1-8. doi: 10.19818/j.cnki.1671-1637.2015.04.001

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Mechanical characteristics and design method of interlocking concrete block pavement

DAN Jing-song, LI Hui, JIANG Han-guan

Abstract: In order to improve the sizes and vertical interlocking ability of interlocking concrete block for traditional pavement, the larger-size interlocking concrete block with rabbet joint was developed, and its mechanical characteristics were studied. The finite element model of interlocking concrete block pavement was set up, the load transfer efficiency between interlocking concrete blocks was simulated by using spring element, and the influences of block sizes, load transfer ability, thickness of granular base and subgrade strength on permanent settlement and vertical strain at the top of subgrade were analyzed.The permanent deformation of subgrade was adopted as control index, and the relationship between normative accumulated axle-load acting number and vertical strain at the top of subgrade was established.Computation result shows that based on the same conditions of base and subgrade, when block sizes increase from 30cm×20cm to 50cm×30cm, pavement deflection decreases by 25%-30%, and subgrade strain decreases by 25%-45%.When the elastic coefficient of rabbet joint increases from 102 N·m^-1 to 108 N·m^-1, pavement defection decreases by 50%-55%, and subgrade strain decreases by 65%-75%.So the larger-size block with stronger load transfer ability can greatly improve the mechanical characteristics of pavement.In pavement design, the stain level at the top of subgrade can be determined according to the traffic condition of road, based on which the thickness of base layer and the sizes of interlocking concrete block are reasonably designed so that the stain level meets the requirement.More>

2015, 15(4): 9-17. doi: 10.19818/j.cnki.1671-1637.2015.04.002

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Damage characteristics of cement concrete pavement for airfield resulted from different de-icing techniques

ZHAO Fang-ran, DU Shi-mei, LIU Xin-chen, AN Wen-bo, XU Xiao-lei

Abstract: Hot air de-icing and chemical de-icing with ethylene glycol and carbamide were simulated for cement concrete pavement of airfield, the mass loss and strength decrease ratio of each concrete specimen were tested, and the the damage rules of de-icing methods and de-icing numbers on cement concrete pavement were analyzed.Analysis result shows that hot air de-icing slowly damages cement concrete specimen, the distinct mass loss only appears after 45 times hot de-icing, but hot air de-icing severely damages the inside structure, and the strength decrease ratio is more than 35% after 50 times hot air de-icing.Though the strength decrease ratio of cement concrete specimen is less than 20% after 50 times chemical de-icing, but the corrosive mass loss of specimen surface is remarkable, and is 8.5%after 50 times carbamide de-icing and is5 times greater than the value after hot air de-icing.Therefore, chemical de-icing is more reasonable than hot air de-icing for protecting the structural strength of cement concrete pavement.On the other hand, hot air de-icing is preferred because of considering aeroengine damage induced by concrete spall on airfield runway, but its influence on pavement structural strength should be paid attention to.More>

2015, 15(4): 18-25. doi: 10.19818/j.cnki.1671-1637.2015.04.003

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Noise reduction effect evaluation of LOS sound barriers

GUAN Bo-wen, LI Shuo, JIANG Yi, ZHAO Guang-yuan, CHEN Shuan-fa

Abstract: In order to evaluate the application effect of line of sight(LOS)sound barrier in the areas with less excessive noise level and fewer households, the noise monitoring and traffic noise model(TNM)analysis at the highway I-465 with LOS sound barrier in Indiana, USA have been done.The influences of pavement type, vehicle speed, traffic volume, noise reduction coefficient, height and extended length of sound barrier on noise reduction level of LOS sound barrier were analyzed, the application effect of LOS sound barrier was evaluated, and the key design parameters were proposed.Analysis result shows that LOS sound barrier can be applied in the areas with less excessive noise level and fewer households.The influence of pavement type on noise reduction is significant.If cement concrete pavement(CCP)is replaced by dense-graded asphalt concrete pavement(DGACP)or open-graded asphalt concrete pavement(OGACP), the range and effective rate of noise reduction can be improved significantly.It is not effective toreduce traffic noise by lowering speed limits, therefore, it is not recommended.For designing LOS sound barrier, the design noise reduction range should be above 6.7dBA, the minimum barrier height should be tall enough to block the view of large vehicle and the maximum barrier height is 6.6m, the optimum height of LOS sound barrier in design year should be determined by traffic noise model analysis.More>

2015, 15(4): 26-33. doi: 10.19818/j.cnki.1671-1637.2015.04.004

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Seismic response of segmented metro tunnel with flexible joints passing through ground fissures

LIU Ni-na, LIU Jun-tao, HUANG Qiang-bing, HAN Dong-dong, Rifat BULUT

Abstract: Earthquake load and site settlement near ground fissures were simulated by shaking table model test.The dynamic responses were studied in sectional metro tunnel with flexible joints passing through active ground fissures.The characterises of uneven settlements, crack development, tunnel accelerations, earth pressures and sectional tunnel strains were studied.Analysis result shows that the site cracks and uneven settlement resulted from the coupling load of site settlement and earthquake load mainly distribute around flexible joints.Each part movement of tunnel with flexible joints is independent.The tunnel located in hanging wall has3.2times peak acceleration of the value in foot wall.The soil pressures near the ground fissure are larger.The soil pressure in hanging wall is 6.7times of the value in foot wall under the coupling load.The strains at the middle of tunnel arch are bigger, the strains at the bottom of thefloor are secondary, and the strains on the top of the arch are less.The strain rate of each section decreases because flexible joints are designed in metro tunnel, and the strains increase little near the ground fissures.The result indicates that the flexible joints can decrease the site deformation and stress concentration of metro tunnel in ground fissure area under the coupling load of site settlement and earthquake load.More>

2015, 15(4): 34-42. doi: 10.19818/j.cnki.1671-1637.2015.04.005

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Vehicle dynamic performance under steel spring failure conditions

LIU Guo-yun, CENG Jing

Abstract: Four failure cases of axlebox steel spring for one side of leading wheelset were considered, namely: the inner and outer rings of steel spring both fractured; just the outer ring fractured; just the inner ring fractured; the whole spring frozen.Then vehicle dynamics model considering the failure cases was set up, and the influence of spring failure on vehicle dynamics performance was analyzed.Simulation result indicates that when the spring is in failure conditions, the equilibrium positions of wheelsets deviate from track center line, the critical speeds of vehicle reduce, the deviation and decrease are largest when the inner and outer rings of steel spring both fracture, and their largest values are about 3mm and 30km·h^-1 respectively.The wheelset with failure spring has larger wheel unloading, the value is largest in the both fractured case and is about 50 kN.For the bogie, the vertical suspension forces decrease at the positions of failure spring and its diagonal axle box, while the vertical suspension forces increase at the positions of another diagonal axle boxes, which results in large torsion force acting on the bogie.Spring fracture more easily brings the safety indexes(such as derailment coefficient and wheel unloading rate)to exceed their limit values, which greatly increases the safety risk of vehicle operation.When the ranges of speed are 200-300km·h^-1 on straight track and 100-300km·h^-1 oncurved track with radius 7 000 m, wheel unloading rates in both fractured case are greater than 0.8.The spring failure has little influence on the lateral riding performance of vehicle, but spring frozen failure will worsen the vertical riding performance of vehicle, and it increases by 0.1when vehicle speed is 300km·h^-1 compared with normal vehicle.More>

2015, 15(4): 43-51. doi: 10.19818/j.cnki.1671-1637.2015.04.006

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Dynamic responses of motor vehicle in low-speed derailment

GUO Li-rong, WANG Kai-yun, WANG Hui-qiong, ZHANG Bing, LIN Jian-hui

Abstract: The low-speed derailment experiment of signal motor vehicle with post-derailment safety device under axle box was carried out.The derailer was installed on the rail to force the vehicle to derail.Acceleration sensors, displacement sensors and strain gauges were used to detect the dynamic responses of derailed vehicle.The motion attitude of derailed vehicle was recorded by using high-speed cameras and surveillance cameras.According to the test data, the ability of overturning resistance for rail and the performance of derailment safety device were verified.The dynamic responses of derailed vehicle and the effects of derailment speed, vehicle mass and track on the responses were studied.Test result indicates that in low-speed derailment, the biggest lateral force between rail and post-derailment safety device is 177.18 kN that is less than the lateral resistance of 510.00 kN, so the post-derailment safety device has the ability to limit the lateral displacement of derailed vehicle by catching the outside of rail after derailment.The derailment process is divided into four stages, including idling, running on the derailer, falling and coasting on the track, at which the dynamic responses of derailed vehicle are increasingwith the increase of derailment speed and vehicle mass.When derailment speed is 22km·h^-1, the derailment distance of CRTSⅡ bi-block sleepers ballastless track is about 15.80 m, while that of CRTSⅠ slab ballastless track is about 20.87 m.Accordingly, the bi-block sleepers of CRTSⅡ bi-block sleepers ballastless track resemble the speed bump and decrease the derailment distance.More>

2015, 15(4): 52-60. doi: 10.19818/j.cnki.1671-1637.2015.04.007

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Block backstepping stabilization control of underactuated USV in polar coordinate system

DONG Zao-peng, WAN Lei, LI Yue-ming, ZHANG Lei, ZHANG Guo-cheng, LIAO Yu-lei

Abstract: To the stabilization problem of underactuated unsymmetrical unmanned surface vessel(USV), a block backstepping approach with multiple inputs and multiple outputs(MIMO)was proposed in polar coordinate system.A drift angle polar coordinate system was designed as bodyfixed moving coordinate system, and Cartesian coordinate system was replaced by polar coordinate system as earth-fixed coordinate system.By combining the drift angle, yaw angle and polar angle, the kinematics and dynamics equations of USV horizontal plane motion in polar coordinate system were obtained, so that the underactuated problem in Cartesian coordinate systems was simplified to the full actuated problem in polar coordinate system.Based on Lyapunov stability theory and the backstepping approach, MIMO block backstepping stabilization control laws for underactuated unsymmetrical USV in polar coordinate system was designed.With the aid of semi-physical simulation platform in the laboratory, an USV model with 1.2 m and 17.5 kg was taken for stabilization control simulation experiment.The proposed block backstepping stabilization control algorithm was compared with the traditional backsteppingcontrol algorithm based on symmetry model.Comparison result shows that the convergence rates of position and yaw attitude increase by about 10 s, the stabilization errors of position and yaw angle decrease by about 0.3 mand 10° respectively, the overshoots of linear velocity and yaw angle velocity reduce by about 0.6m·s^-1 and 2 rad·s^-1 separately, so the proposed backstepping control method has higher reliability, stability and accuracy.More>

2015, 15(4): 61-68. doi: 10.19818/j.cnki.1671-1637.2015.04.008

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Energy efficiency model of marine main engine

FAN Ai-long, YAN Xin-ping, YIN Qi-zhi, SUN Xing, CHEN Qian-kun, ZHANG Yong-bo

Abstract: According to the hull-engine-propeller relationship, the energy efficiency model of marine main engine was established based on the energy transfer within marine power plant and MATLAB/Simulink simulation platform.An inland river cruise ship was chosen as a research object, and the open-water characteristic curves of propeller were obtained by using the regression polynomial method according to the parameters of hull and main engine.Several sensors(such as fuel consumption instruments) were amounted on the target ship, the instantaneous fuel oil consumption of main engine, the marine speed relative to ground, and the marine speed relative to water were collected, and the real main engine energy efficiencies were calculated.The distribution characteristic of water speed was analyzed according to actual collected data.The energy efficiencies of main engine under different water speeds and marine speeds relative to water were calculated based on the simulation model.The actual data andsimulation results were compared and analyzed, and the model was verified.Verification result indicates that water speeds are almost normal distribution with skewness of-0.032, the one-toone correspondence between real energy efficiency and marine speed relative to water is not observed, but their relationship is a scattered distribution with correlation coefficient of 0.824.The established energy efficiency model can accurately evaluate the energy efficiency level and changing rule of main engine in navigation process, and the error is less than 10.5%.More>

2015, 15(4): 69-76. doi: 10.19818/j.cnki.1671-1637.2015.04.009

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Vehicle stability control based on chassis multiple subsystem coordinated control

ZHAO Shu-en, LI Yu-ling, YU Qiang

Abstract: Based on the differences of chassis key subsystems influences on vehicle stability and effective acting regions, the nonlinear characteristic of tires and the dynamics coupling relation among vehicle chassis subsystems were comprehensively considered, and the 14-DOF full vehicle model was built.Nonlinear H∞ control and fuzzy control were separately utilized for chassis steering, braking and suspension to study the control performances.Multi-level hierarchical control theory was adopted to establish vehicle stability coordinated control system including organization, coordination and execution level.Sliding mode control theory and inverse tire model were used to translate the generalized target control forces and moments from organization level into tire sideslip angle and slip ratio.Based on the principle of function distribution, the control function of each subsystem was coordinated, the function decoupling of vehicle chassis complex system was realized, and full vehicle stability coordinated control system was simulated.Simulation result shows that the control effect on vehicle stability by combined control of ABS(anti-lock braking system)and SAS(semi-active suspension system)is relatively poor, butjoining AFS(active front steering)can significantly improve vehicle handling stability.Compared to vehicle chassis subsystem combined control, multi-level hierarchical coordinated control can improve vehicle stability preferably, reduce the braking distance and keep the slip ratio near the target value 0.2basically.More>

2015, 15(4): 77-85. doi: 10.19818/j.cnki.1671-1637.2015.04.010

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Temperature distribution of friction plate for dry clutch

WANG Yang-yang, LIU Qian

Abstract: In view of the thermal failure of dry clutch in automobile transmission process, the temperature distribution of friction plate was studied.Based on the working principle of dry clutch, the clutch engagement model including its active and driven parts, friction surface pressure and friction coefficient was established. Combined with axial elastic element characteristics and release bearing structure characteristics that the contact surface of diaphragm spring rotates and the contact surface of separated forked plectrum does not rotate, an annular pressure sensor was fixed on the contact surface of separated forked plectrum, and the real-time friction pressure of clutch was estimated.Based on the dry clutch test bench and the friction coefficient model of dry clutch, the friction transfer torque and slipping friction power on the continuous operation of 400 swere estimated.The heat load of friction surface of dry clutch was calculated based on three kinds of boundaries including heat absorption from environment, heat producing by friction, and heat dissipation in convection.The thermal distortions of friction plate in 2 conditions were analyzed, including instantaneous impact engagement and frequent engagement.Analysis result shows that in the condition that the time instantaneous impact engagement is 2s, the maximum heat distortion of friction plate can reach 0.188 mm, and thetemperature of friction plate rises obviously.In frequent engagement condition, the temperature distribution of friction plate mainly depends on the second boundary of slipping friction heat load before 200 sof clutch engagement, and it depends on the second and the third boundary of convective heat after 200 sof clutch engagement.More>

2015, 15(4): 86-92. doi: 10.19818/j.cnki.1671-1637.2015.04.011

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Effectiveness test of speed-limit sign in one-way closed work zone for expressway

JIA Xing-li, FU Zhi-peng, XU Jin-liang, CHEN Wen-hui, JING Li-zhu

Abstract: The warning effectiveness of traffic sign, especially the speed-limit sign, in one-way closed work zone of experessway, was studied by using field tests and statistical analysis.The grading speed-limit program was proposed and the test program for traffic sign effectiveness was set up.A typical expressway section was chosen to test the effectivenesses of existing traffic sign, speed-limit sign position, grading speed-limit and optimizing traffic sign.Test result shows that the effectiveness of existing traffic sign, especially the speed-limit sign, is insufficient for speed-limit.In the expressway test section, after the vehicles pass through the speed-limit sign, they still have much higher speeds than the speed-limit values, and the speed reductions of the vehicles are very small.Through the optimization of traffic sign using grading speed-limit, the vehicles after passing through the work zone have significant reductions in their speeds, the speed of passenger car reduces by 38km·h^-1, and the speed of freight car reduces by 32km·h^-1.The difference value between passenger car running speed and the speed-limit value has reduced from 60km·h^-1 to 15km·h^-1, this kind of speed difference value for freight car is from 40km·h^-1to 5km·h^-1, the speeds of vehicles are very close to the speed-limit values, and the variation tendency of traffic flow speed is consistent with the speed-limit difference value, so the effectiveness of traffic sign is greatly improved by the grading speed-limit optimization.More>

2015, 15(4): 93-100. doi: 10.19818/j.cnki.1671-1637.2015.04.012

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Computation model of standing-passenger density in urban rail transit carriage

WU Qi-bing, CHEN Feng, GAO Yong-xin, LI Xiao-hong, ZHAI Qing-sheng

Abstract: To determine a scientific and reasonable standing-passenger density in urban rail transit carriage, the impact of standing-passenger density on comfort was studied in the perspective of standing passenger's comfort. Through analyzing and quantizing the data collected from questionnaires and field measurements, two main factors namely spatial congestion and carriage microenvironment were obtained.Based on the means of linear weighting method and customer empowerment method, a static comfort evaluation model was built by combining the 2factors.Considering the effect of long-time standing on comfort, and comparing to the fatigue index, the static comfort evaluation model was modified.A questionnaire survey was conducted to verify the time reduction factor and determine the parameters. A standing-passenger density-based generalized comfort evaluation model was built.Based on the generalized comfort evaluationmodel, a reasonable standing-passenger density model was proposed by using backstepping approach.Based on the built model, the Line 4of the Beijing Subway-Daxing Line was used for comfort evaluation.Analysis result indicates that the comfort evaluation can reflect the change of standing-passenger density timely and accurately, and the comfort evaluating result can help improving the service level of urban transit.The reasonable standing-passenger densities of Line4 of the Beijing Subway-Daxing Line meeting the comfortable level, designed level, and overcrowding level are 3.1, 4.2, 4.7person·m^-2, respectively, the calculated densities are corresponding to 3.0, 4.0, 6.0person·m^-2 of vehicle design capacity of American, and also consistent with the survey result, so the model can be used to determine the standing-passenger density in the planning and design of urban transit.More>

2015, 15(4): 101-109. doi: 10.19818/j.cnki.1671-1637.2015.04.013

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Automatic detection method of roads from fuzzy aerial images

LIU Sheng, WANG Wei-xing, WANG Shan-shan, HAN Ya, HUANG Ling-xiao, ZHANG Xin

Abstract: In order to accurately detect the road from fuzzy aerial images, an automatic road detection method was proposed based on the characteristics of roads in images.The fuzzy images were enhanced by using multiple scale Retinex algorithm.The main road segments in images were detected by using improved Canny edge detection algorithm, and the high and low thresholds in gradient images were automatically obtained by using cross-entropy theory and Bayesian judgment theory, the gray image was transformed into the binary images, and the skeletons of linear target in the image were extracted.The noise was filtered based on the shape and size characteristics in the linear target, the gaps between segments were linked based on the curvature and the distances between segments, and the detected road was adjusted and modified by combing the edge and the original image information.The proposed automatic road detection method was compared with several widely used traditional algorithms, such as Otsu threshold segmentation algorithm, Canny edge detection algorithm, and graph theory based on the minimum segmentation algorithm.a single road, cross roads and several roads in fuzzy images were detected by using the proposed road detection method.Detection result indicates that as forfuzzy or uneven-illumination aerial road images, the trunk roads can be clearly displayed after enhancing images by Retinex algorithm, while the conventional image segmentation algorithm can not do.The trunk road can be well extracted by using the improved Canny edge detection algorithm with image post-processing function.In the detection of single road, cross roads and several roads in the fuzzy aerial images, the target roads can be clearly detected by using the proposed method.The effect of detection method is close to the result of artificial recognition.More>

2015, 15(4): 110-117. doi: 10.19818/j.cnki.1671-1637.2015.04.014

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Time correction method of asynchronous cameras in road monitoring system

LIANG Hua-gang, CHENG Jia-le, SUN Xiao-nan, RU Feng

Abstract: In order to improve the reduction accuracy of traffic incident, a high accuracy time correction method of traffic scene 3Dreconstruction was proposed based on binocular epipolar geometry relationship.The frame sequences of multiple asynchronous cameras were analyzed, and the time correction model of asynchronous cameras was established.In order to correct the time error of multiple asynchronous cameras, corresponding frame time synchronous matching was carried out by using the epipolar geometry constraints and the constraint principle of minimum distance from point to pole line.The shooting system composed of 2asynchronous cameras was built, the time matching error of corresponding frame was analyzed.The time error of start frame in video sequences was estimated, and the recovery of high precision dynamic scenes was realized.High-speed moving vehicle was simulated by using flashing LED, and the range of time error was estimated.In order to further validate the effectiveness of the method in actual road environment, four cameras were used to shoot the video sequences of freefall ball, thecomparative tests were respectively carried out by using time correction method based on similarity discrimination and the proposed method.Test result indicates that when the exposure time of camera is 1/30 s, and the cycle of high-speed flashing light with is 6.59 ms, the time error range of start frame is from 0to 6.59 ms, the corresponding frames ratio is above 88.1%.Compared with the time correction method based on similarity discrimination, the proposed method performs well.Compared with the several traditional time correction methods, the accuracies of time error matching and the 3Dreconstruction of asynchronous cameras in road monitoring system are significantly improved.More>

2015, 15(4): 118-126. doi: 10.19818/j.cnki.1671-1637.2015.04.015

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2015 Vol. 15, No. 4

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