2011 Vol. 11, No. 5

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Influence of rubber particles on micro-surfacing performance and its noise-reduction effect
LING Tian-qing, LI Yao-nan, DONG Qiang, ZHAO Mei-ling, ZHENG Zhi-neng, ZHAO Zhi-jie
Abstract: The impact of adding rubber particles on the water stability, wear resistance and other road performances of slurry mixture were compared by using wet track abrasion test, load wheel test and stability and resistance to compaction test.The attenuation characteristics of tyre vertical vibration that happened on micro-surfacing adding rubber particles were studied through tyre-road vibration test device.Test result shows that the workability of slurry mixture is improved by adding rubber particles, the mixing time is prolonged, the early strength decreases by a small margin, and bitumen aggregate ratio is needed to raise by about 1% to achieve the same road performance.When the content of rubber particles is not more than 5%, the requirement of wheel rut deformation on micro-surfacing pavement is met.Comparing with traditional micro-surfacing pavement, the attenuation coefficient of vertical vibration increases by 3%-13% on micro-surfacing pavement adding 2%-5% rubber particles overlayed asphalt pavement, and the attenuation coefficient of vertical vibration increases by 16%-24% on that overlayed cement pavement.More>
2011, 11(5): 1-5. doi: 10.19818/j.cnki.1671-1637.2011.05.001
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Computation model of bridging stress for flexible short fiber in asphalt at low temperature
DING Zhi-yong, PENG Bo, WANG Zhen-jun
Abstract: The characteristics of flexible-fiber-reinforced brittle materials were analyzed, and a mechanical model of single fiber pulled out from asphalt at low temperature was established.In spherical coordinate, a computation model of bridging stress for short fiber was established when short fibers uniformly distributed in asphalt, and the bridging stress was computed when asphalt ruptured.The bridging stress was measured by using tensile test and large size fiber asphalt samples at low temperature.The calculation model was corrected by fitting calculated and measured values of bridging stress.Analysis result shows that the maximal fitting error is 6.67%, so, the mechanics-experience method can be used to study the bridging stress of flexible short fiber at low temperature.More>
2011, 11(5): 6-11. doi: 10.19818/j.cnki.1671-1637.2011.05.002
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Gradation design method of coarse aggregate for interlocking-dense cement concrete
WANG Lei, MA Biao, KOU Jun-ping
Abstract: According to the roles of coarse aggregate in cement concrete, the aggregate filling ratio was put forward to present the relationship between coarse aggregate gradation structure and aggregate particle.Based on particle interference theory and particle filling theory, the design idea of volumetric method was consulted, the gradation design method of coarse aggregate with interlocking skeleton structure for cement concrete was put forward, and the corresponding design software was developed.On the basis of cement concrete design requirements of testing project, the coarse aggregate gradation was calculated, and the design mix proportion of interlocking-dense cement concrete was determined by using software.Furthermore, the concrete performances were tested and verified.Test result indicates that the coarse aggregate gradation with interlocking skeleton structure directly determined by using the software is more coarse than the lower limit of the gradation range recommended by the technical specification for construction of highway cement concrete pavements (JTG F30—2003), and its whole skeleton structure is better.The slump of interlocking-dense cement concrete is 25 mm and meets the workability requirement 10 to 30 mm.The 28 days flexural strength is 7.9 MPa, which is greater than the preparation strength 7.7 MPa and meets the design strength requirements.The maximum number of frost cycles tested by using quick freezing method is 250, and the froze-resistance index is 49.2%, which meets the frost cycles requirement 200 for cold region.More>
2011, 11(5): 12-17. doi: 10.19818/j.cnki.1671-1637.2011.05.003
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Practical updating method of finite element model for long-span steel truss suspension bridge
HAN Wan-shui, WANG Tao, LI Yong-qing, LI Yan-wei, HUANG Ping-ming
Abstract: Based on the engineering background of the super long-span steel truss suspension bridge over Sidu River Deep-Cutting Gorge on Hu-Rong National Highway, the influences of suspension bridge structural nonlinear and gravity stiffness were comprehensively considered, an updating programme of bridge model was developed by using APDL of ANSYS, and the synchronous calculation on finite element analysis and model updating was realized.The influence degrees of different optimization algorithms, different objective functions and different constraint conditions on model updating effects were compared, the influences of measured suspender forces and expansion joint rigidity parameters were analyzed, and a practical updating method, which could fully reflect the structural properties of suspension bridge, was proposed.In the method, the frequency residual was taken as objective function, the frequency, modal parameters and other static information were taken as constraint conditions, and the zero order optimization was carried out.Calculation result shows that the deviations between the computed and measured responses of structural static and dynamic forces for the updating model decrease significantly, the static deformation errors are controlled within 8%, the frequency errors are controlled within 5%, the parameter variations of the model are reasonable, the physical meanings of the parameters are ensured, so the benchmark finite element model of super large bridge over Sidu River is obtained and feasible.More>
2011, 11(5): 18-27. doi: 10.19818/j.cnki.1671-1637.2011.05.004
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Evaluating system of integrated grounding effectiveness on high-speed railway
WANG Bo, WU Guang-ning, ZHOU Li-jun, DONG An-ping, GAO Guo-qiang, FAN Jian-bin
Abstract: The decreasing degree of rail potential was taken as a standard for evaluating integrated grounding effectiveness.The relationship among rail potential, integrated grounding line impedance and shunt coefficient was analyzed.The integrated grounding effectiveness evaluating system(IGEES) was developed, and the main influence factors of integrated grounding line impedance and shunt coefficient were studied.The theoretical result and measurement result of IGEES were compared.Analysis result shows that rail potential increases with the increasing of integrated grounding line impedance, and decreases with the increasing of shunt coefficient.The material and size of integrated grounding line, soil resistivity and transversal connection interval have great effect on grounding impedance and shunt coefficient, while the effect of buried depth is relatively insignificant.The differences between IGEES results and measurement results of grounding impedance and shunt coefficient are 18%, 5.62% respectively.The calculation error of IGEES is lesser, and IGEES can be used in the design and construction of integrated grounding system on high-speed railway.More>
2011, 11(5): 28-34. doi: 10.19818/j.cnki.1671-1637.2011.05.005
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Operating properties of preinjection NC air-powered engine
CHEN Shi-an, ZHANG Shi-jin, HE Ren
Abstract: To settle the seal matters in valve train system, a new preinjection NC air-powered engine was designed, its thermo-dynamics model was proposed.The model was made up of the thermo-flow rate equations of preinjection cylinder & working cylinder and the dynamics equations of the engine.The operating process and efficiency factors of the engine were quantitatively researched by varying parameter dynamic simulation.Simulation result shows that the temperature of preinjection cylinder is close to 383.5 K when air intake ends, so the key control parameter of the engine is the expected control pressure.Under comparative operating conditions, when the effective flowing area of exhaust pipe solenoid valve changes only, its values are 7.854 0×10-5, 1.570 8×10-4, 3.141 6×10-4 m2 respectively, the corresponding efficiencies of the engine are 0.575 8, 0.777 7 and 0.902 2 respectively, so the effective flowing area of exhaust pipe solenoid valve is the key efficiency factor of the engine.More>
2011, 11(5): 35-41. doi: 10.19818/j.cnki.1671-1637.2011.05.006
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Calculation method of cross wind security domain for high-speed train
CUI Tao, ZHANG Wei-hua
Abstract: Based on parameter transmission, solution to control and dynamic mesh techniques, the cross wind fluid dynamics model and the multi-body system dynamics model of high-speed train were established.By collaboratively simulating the external flow field and system response of train, the stable attitudes and aerodynamic loads under different cross wind environments were obtained.The running safety indexes were studied, the critical speeds of running safety under different cross wind environments were analyzed, and the security domain was defined.Calculation result indicates that with the increases of train speed and cross wind strength, the transfinite phenomena of wheel unloading rate, derailment coefficient and lateral wheelset force appear successively.While train speed is less than 300 km·h-1, all wheelsets of leading vehicle almost have upwind migration.While train speed is 300 km·h-1 and cross wind speed is 30 m·s-1, and train speed is 350 km·h-1 and cross wind speed is more than 25 m·s-1, the first and second wheelsets have downwind migration, the third and fourth wheelsets have upwind migration.The higher train speed is, the lower the cross wind resistance ability is, and the sensitivity of train critical speed on cross wind strength will increase.More>
2011, 11(5): 42-48. doi: 10.19818/j.cnki.1671-1637.2011.05.007
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Influence of braking pipe on braking performance for heavy haul train
WEI Wei, DU Nian-bo
Abstract: With fluid dynamics theory, the models of braking pipe and distributing valve for heavy haul train were built, the equations of braking pipe and boundary point were solved, the braking system performances in braking process were simulated, and the influence of the lengths of main pipe and branch pipe on the braking performances was analyzed.Analysis result shows that under common braking, when the length of main pipe increases from 13.24 m to 17.24 m, the decompression time of braking pipe increases by 30.75%, and the boost time of braking cylinder increases by 20.45%.The influence of main pipe on common braking is even stronger than that of main pipe on emergency braking.Under common braking, when the length of branch pipe increases from 0.50 m to 5.00 m, the decompression time of braking pipe increases by 6.63%, and the boost time of braking cylinder increases by 5.22%.The influence of branch pipe on common braking is almost same for that of branch pipe on emergency braking.The increase length of braking pipe reduces the decompression speed of braking pipe and the boost speed of braking cylinder.The influence of the length of main pipe is stronger than that of branch pipe, and the influence becomes obviously with the increase of the distance between car and locomotive.More>
2011, 11(5): 49-54. doi: 10.19818/j.cnki.1671-1637.2011.05.008
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Coupling dynamics performance of vehicle-track under cross wind
LI Tian, ZHANG Ji-ye, ZHANG Wei-hua
Abstract: A coupling dynamics model of vehicle-track was established by using multi-body system dynamics theory, a new explcit integration method was used to solve the dynamics equations of the model, wheel-rail normal contact force was calculated by using nonlinear Hertz contact theory, wheel-rail creep force was calculated by using Shen-Hedrick-Elkins model, and vehicle-track coupling dynamics program was written.The influence of track structure on the dynamics performances of high-speed train was studied, and the dynamics performances and running attitudes of high-speed train under different cross wind conditions were analyzed.Analysis result indicates that when train speed is 350 km·h-1 and cross wind speed is 15 m·s-1, the maximum lateral acceleration of car body is 0.45 m·s-2, the maximum vertical displacement of car body is 24.5 mm, car body traverses 80.0 mm toward the leeward side, and the maximum roll angle of car body is 2.23°.The maximum wheel unloading rate of the first wheelset is close to 0.80, the second and fourth wheelsets traverse toward the leeward side, and the wheels on the leeward side have climbing track phenomenon.The lateral displacement of the second wheelset is largest, and reaches 7.4 mm.Under cross wind, the safety indexes of high-speed train become worse, car body acceleration changes unconspicuous, and car body traverses towards the leeward side.The second wheelset is most dangerous in all wheelsets.More>
2011, 11(5): 55-60. doi: 10.19818/j.cnki.1671-1637.2011.05.009
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Pressure gradient experiment and influence factor analysis of automotive hydraulic ABS
XU Guo-min, MA Ming-xing, HUANG Jin-chuan, GUAN Yan-cai
Abstract: Based on anti-1ock braking system(ABS) hydraulic test bench, PCMCIA-DAQ1200 acquisition card and LabVIEW software were used, the test program of ABS pressure gradient was written, and the data acquisition was realized automatically.The various experimental tests of ABS pressure gradient were carried out including common braking, long-plus and long-reduction braking and step braking.Test result shows that under common braking, the maximum and minimum decompression gradients are -90.5 and -94.8 MPa·s-1 respectively, and the maximum and minimum pressurization gradients are 4.1 and 2.7 MPa·s-1 respectively.Under long-plus and long-reduction braking, the maximum and minimum decompression gradients are -12.1 and -23.0 MPa·s-1 respectively, and the maximum and minimum pressurization gradients are 21.0 and 4.9 MPa·s-1 respectively.Under step braking, the maximum and minimum decompression gradients are -1.2 and -3.2 MPa·s-1 respectively, and the maximum and minimum pressurization gradients are 3.2 and 1.2 MPa·s-1.The main cylinder pressures of common braking, long-plus and long-reduction braking and step braking are 8, 12, 15 MPa respectively.More>
2011, 11(5): 61-68. doi: 10.19818/j.cnki.1671-1637.2011.05.010
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A novel detection system of automobile ABS
HAO Ru-ru, ZHAO Xiang-mo, MA Jian, XU Zhi-gang
Abstract: In order to improve the detection efficiency of automobile ABS, a novel detection system was developed based on bench.The inertia of moving automobile was simulated by using the rotational inertia of flywheel.Four torque controllers were adopted to load different torques on four rollers supporting four wheels of automobile, so that different road adhesion coefficients were simulated.CAN-bus-based distributed network control technology was used to complete the motion control of bench and the data acquisition of automotive speed.BP neural network was used to analyze the test data for its self-learning function.The summarized mapping relationship of ABS work states was stored in the network, and the automatic classification of test results was achieved by using the network.Comparative analysis of bench test result and road experiment result for ABS shows that the results are basically same, the errors of main parameters are less than 4%, so bench test can more accurately reflect the brake performances of automobile equipped with ABS in different road environments.More>
2011, 11(5): 69-75. doi: 10.19818/j.cnki.1671-1637.2011.05.011
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Multi-objective lattice-order decision-making method of scheme selection for rail transit network
LIU Yu-zeng, QIAN Bing-yi
Abstract: Aimed for the rational limitation of decision-maker, the multi-objective lattice-order decision-making method was introduced into the scheme selection of rail transit network.The evaluation index system of multi-objective lattice-order decision-making for urban rail transit network was constructed.Each index was turned into dimensionless number according to its type.The relative weights of evaluation indexes were worked out by synthesizing the subjective ones of decision-makers and the objective ones of data discrete degrees.Combining with decision matrix, the comprehensive difference degree of each scheme was calculated in order to achieve the lattice order of alternative schemes, and the decision-making method was applied to evaluate four rail transit network plans of some city.Analysis result shows that the comprehensive difference values of four plans are 0.66, 0.56, 0.24, 0.83 respectively, and the order result is consistent with actual situation, so the method is rational.More>
2011, 11(5): 76-82. doi: 10.19818/j.cnki.1671-1637.2011.05.012
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Location model of railway passenger station
ZHANG Tian-wei, NIE Lei, GAO Gui-feng
Abstract: Influence factors were divided into non-mandatory meet qualitative factors, mandatory meet qualitative factors and quantitative factors, and a location model of railway passenger station was proposed.The generated method and process of three kinds of influence factors were given.The contribution value was introduced to lessen the controversy caused by qualitative factors, and the comprehensive contribution preset value was changed to produce potential location sets confined the meet qualitative factors.An objective function determined by quantitative factors was proposed, and the 0-1 programming model was established subjected to all kinds of constraints.A calculating example according to railway actuality was designed to illustrate the model, and the model was solved after related parameter values were given.Analysis result shows that the construction cost of existing railway passenger station's potential location is 60% and 75% of other two potential locations' costs respectively, it is selected as candidate location, so construction cost is important influence factor to the location of railway passenger station.More>
2011, 11(5): 83-87. doi: 10.19818/j.cnki.1671-1637.2011.05.013
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Driving risk evaluation model of freeway interchange entrance area
WANG Xiao-fei, FU Xin-sha, GE Ting
Abstract: The traffic characteristics of freeway interchange entrance area were analyzed, and the concept of collision risk index(CRI) was put forward.The coefficient of collision possibility, speed difference between two colliding vehicles, colliding speed and acceleration of following vehicle, vehicle spacing on target lane were taken into consideration.Traffic collisions that may occur in entrance area were divided into five kinds, and the occurrence conditions and risk evaluation models of five cases were studied correspondingly.3D numerical simulation was carried out for different vehicle running speeds on main line, space headways, vehicle running speeds on entrance ramp, and the driving risk variation laws of entrance area were obtained.Analysis result shows that with higher running speed on main line, smaller vehicle spacing and higher speed difference, driving risk will increase.More>
2011, 11(5): 88-92. doi: 10.19818/j.cnki.1671-1637.2011.05.014
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Structure analysis and calculation method of freight turnover for regional highway
YANG Ming, QIN Hua-rong, CHEN Yin-san
Abstract: In order to solve the problem of the structural data loss of highway freight turnover, highway freight turnover was divided into vehicle freight turnover and highway network freight turnover.Relying on vehicle annual inspection platform, sampling survey was carried out, and vehicle freight turnover was obtained.According to the proportion of vehicle travelling mileage, vehicle freight turnover was assigned to different highway networks.Based on expressway toll systems and general highway traffic observation stations, traffic data were obtained.Combined with field sampling investigation data in 24 h, regional highway network freight turnover was estimated, and highway network freight turnover was breakdown according to the proportion of vehicle registered place.Linking vehicle freight turnover to highway network freight turnover, the structure and distribution of total freight turnover were obtained, and the generalization result in Jiangsu Province was analyzed.Analysis result shows that from the point of vehicle freight turnover, the proportions of local and non-local trucks in Jiangsu Province are 65.39%, 34.61% respectively.From the point of highway network freight turnover, 43.00% of total freight turnover is completed by expressway network, 31.61% of total freight turnover is completed by general toll highway, and 25.39% of total freight turnover is completed by other highways.From the point of vehicle registered place, 40.80% of total freight turnover is completed by the vehicles registered in Jiangsu Province, and 59.20% of total freight turnover is completed by the vehicles registered in other provinces.From the point of expressway freight turnover, the freight turnover of the vehicles in other provinces is four times than that of the vehicles in Jiangsu Province.More>
2011, 11(5): 93-100. doi: 10.19818/j.cnki.1671-1637.2011.05.015
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Green wave coordinated control optimization models oriented to different bidirectional bandwidth demands
LU Kai, ZHENG Shu-jian, XU Jian-min, LI Lin
Abstract: A new performance index function of green wave coordinated control model was built by introducing bandwidth proration impact factor and bandwidth demand ratio.The green wave coordinated control optimization models oriented to different bidirectional bandwidth demands were proposed for MAXBAND(MULTIBAND) model and general bidirectional green wave coordinated control model respectively.Two cases that bidirectional green wave bandwidths existed or not were considered, and the design effects of different control models were compared.Analysis result indicates that when the coordinated control effect of bidirectional green wave could not be achieved, the optimization model will choose one-way green wave coordination control to guarantee maximum total bandwidth and prorate the bandwidth fully to the direction with higher bandwidth demand.While the coordinated control effect of bidirectional green wave could be achieved, the optimization model will not only guarantee maximum total bandwidth, but also prorate the bandwidth according to the bandwidth demand ratios of different directions.So the models are reasonable and effective.More>
2011, 11(5): 101-108. doi: 10.19818/j.cnki.1671-1637.2011.05.016
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Control model of variable speed limit based on finite horizon Markov decision-making
WANG Wei, YANG Zhao-sheng, ZHAO Ding-xuan
Abstract: The function of variable speed limit(VSL) on expressway mainline was analyzed, and the existing methods of speed limit were studied.The control process of VSL was taken as Markov decision-making process of discrete time.A model of VSL based on reinforcement learning and finite horizon Markov decision-making was proposed.The model was dynamically adjusted through interacting with traffic environment, and solved by using finite horizon backward recursive iterative algorithm.The traffic environment of Chang-Ji Expressway was simulated by using Paramics.Analysis result shows that average traffic volume doesn't reduce, but increases by 3.20% when average limit speed decreases by 6.25% compared with design speed.So the model is feasible to increase traffic volume and improve traffic condition on expressway mainline effectively.More>
2011, 11(5): 109-114. doi: 10.19818/j.cnki.1671-1637.2011.05.017
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Static test method of high-precision attitude measurement technology
TANG Jun, WANG An-guo, ZHANG Lei
Abstract: In the case of specific observation time and place, the attitude measurement system was assumed in reference attitude, and the trace and time informations of one star could be calculated in advance.The actual movement trace and time information of star were made in accord with calculated trace by adjusting equipment base, and reference attitude was established.The output information of attitude measurement system was compared with reference attitude, and a static test method of high-precision attitude measurement technology was proposed and carried out.The system error of attitude measurement equipment was detected exactly, and the triaxial attitude information of system output was corrected.Calculation result shows that the mean-square deviations of heading angle, roll angle and pitching angle are 19.98″, 11.43″, 12.05″ respectively, the static test method can achieve the accuracy of arc second, and its precision is higher.More>
2011, 11(5): 115-119. doi: 10.19818/j.cnki.1671-1637.2011.05.018
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Simulation evaluation of safeguard measure for traffic safety on montane highway
GUO Feng-xiang, XIONG Jian, QIN Ya-qin, WAN Hua-sen
Abstract: The tunnel group, climbing section and mixed traffic section of Yunnan Xiaomo Highway from K109+600 to K122+024 were selected as experiment sample sections, and their static and dynamic 3D models were established by using virtual scene generation system.Central isolation installations such as lodging warning column, visual marking, conventional marking were placed in tunnel, and additional lane was set at climbing section and mixed section.The average speeds and lateral positions of vehicles at three sample sections were comparatively analyzed, and the effects of three safety safeguard measures were evaluated.Analysis result indicates that in tunnel, the average speed standard deviations for three central isolation installations are 9.74, 10.01, 10.40 km·h-1 respectivehy, and the average lateral position standard deviations are 0.54, 0.70, 0.69 m respectivehy.It can be seen that by setting lodging warning column, the speed and lateral position of vehicle can keep well.When traffic volume is less than 1 000 pcu·h-1 at climbing section, it is beneficial to improve vehicle speed on main line by setting additional lane.When non-motor vehicle volumes are 500 and 800 pcu·h-1 at mixed traffic section, there are higher speed, smaller speed deviation and bigger lateral position after setting additional lane.Setting additional lane is beneficial to improve and maintain vehicle speed, and reduce conflicts to opposed vehicle.More>
2011, 11(5): 120-126. doi: 10.19818/j.cnki.1671-1637.2011.05.019
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