交通运输工程学报

Relationship between gradation type and segregation degree for asphalt mixture

HUANG Qi, ZHAO Xin, LEI Yu, SHA Ai-min

Abstract: Six curves of gradation types with different properties were designed, the gradation constitutes, texture depthes and densities of asphalt mixtures with different gradations at five different positions were detected, and the segregation degrees and rules of asphalt mixtures in construction process were investigated. By studying the relationship between the mean squares of test data and the fractal dimensions of aggregates, a linear regression model of the relationship were established. Using the model, the gradation of asphalt mixture was evaluated, and the degree of segregation was forecasted. Analysis result shows that the mixtures with different segregation degrees from big to small are as follows: anti-S type, discontinuous type, micro-arch type above the maximum density curve, S type, maximum density curve type and micro-arch type under the maximum density curve. The probability value of F(1, 5) significance test is 0.013, which is significantly less than the significance level of 0.05, so the linear model is effective.More>

2009, 9(2): 1-6. doi: 10.19818/j.cnki.1671-1637.2009.02.001

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Performance evaluation and technical requirement of sealant and filler in asphalt pavement

LI Feng, HUANG Song-chang, XU Jian, QIN Yong-chun

Abstract: In order to evaluate the performance of hot-applied type sealant and filler in asphalt pavement, Chinese sealant and filler conditions and performance requirements were analyzed, five test methods on cone penetration, softening point, flow, resilience and tension at low temperature were respectively determined by reference of ASTM D5329, eleven samples of sealant and filler were tested, and five performance evaluation indices and their technical requirements were defined. Test result shows that the softening points of ten samples are over 80 ℃, the flow values of nine samples are under 5 mm, and only three samples pass three cycles with 50% extension in low-temperature tension test. So sealants and fillers used in China have good high-temperature performances, but have poor low-temperature characteristics.More>

2009, 9(2): 7-11. doi: 10.19818/j.cnki.1671-1637.2009.02.002

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Numerical simulation of split test process for asphalt mixture under heterogeneous state

QIU Yan-jun, YAN Chang-he, AI Zhang-fa

Abstract: In order to analyze the influence of heterogeneity on asphalt mixture split test, a realistic failure process analysis program was used to conduct the numerical simulation of split test. The Weibull distribution of asphalt concrete strength coefficient was assumed in the digital test to study the stress state and cracking process. Marshall split test was conducted on AC-10 specimen, and its split failure process was simulated. Analysis result shows that the cracking state tends to dispersion with the decrease of homogeneous degree, but the cracking state of specimen with high homogeneous degree is more regular. Affected by the stochastic distribution of heterogeneous element, the stress distribution presents multiple peaks in specimen split process. The split process of Marshall specimen in digital test is similar with that in physical test.More>

2009, 9(2): 12-16. doi: 10.19818/j.cnki.1671-1637.2009.02.003

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Overlay design considering remnant life of old asphalt pavement

CHEN Jun, HUANG Xiao-ming

Abstract: The fatigue performances of old asphalt pavement before and after overlay were simulated by asphalt mixture fatigue tests with two-amplitude load in laboratory. The theory of equivalent damage was used to make conversion from the loading frequencies of old base course before overlay to that after overlay. The formula was founded to forecast the remnant lives of old pavement surface and base course after overlay. Overlay design method considering remnant life of old pavement and checking computation of overlay construction were proposed. The method was applied in maintenance of Donggang Expressway in Shandong Province. Analysis result indicates that the overlay fatigue lives of the two structures both meet the requirement of traffic volume of Donggang Expressway. Considering economic benefits and the harmony between traffic volume and overlay fatigue life, the second overlay structure with twelve centimeters LSPM-25 is more suitable for Donggang Expressway.More>

2009, 9(2): 17-21. doi: 10.19818/j.cnki.1671-1637.2009.02.004

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Mechanical properties of reinforced asphalt concretes with different position grids

LIU Jian-lan, WANG Chao-hui, WANG Xuan-cang

Abstract: In order to study the internal law of mechanical properties for reinforced asphalt concretes with different position grids, wheel rolling specimens and Marshall formation samples were respectively made. Interlayer shear and pull-out tests were conducted. The influence of grid position on concrete strength property was studied. Dimensionless toughness index was introduced to evaluate splitting strength test. Analysis result shows that the mechanical property of asphalt concrete reinforced with grid is better than that without grid. The interlayer resisting shear abilities of reinforced asphalt concretes with different position grids are similar at 25 ℃ and 60 ℃. When grid is set in the middle of concrete sample, the interlayer caking capability of reinforced concrete is best, its compression strength, compression resilience modulus and toughness are maximum. When grid is far away from the middle, the splitting strength of reinforced concrete is maximum.More>

2009, 9(2): 22-27. doi: 10.19818/j.cnki.1671-1637.2009.02.005

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Dynamic characters of compacted silt under cyclic load

GUAN Yan-bin, XIAO Jun-hua, CHEN Jian-guo

Abstract: In order to investigate the dynamic characters of compacted silt under cyclic load, the variations of its dynamic stress and water content were considered. The cumulative plastic deformation, resilient modulus and critical dynamic stress of compacted silt were studied based on stress-controlled dynamic triaxial test in laboratory. Test result shows that the cumulative deformation of compacted silt is closely related with its dynamic stress and water content. The higher its dynamic stress is, the faster the growth speed of its cumulative deformation with the increase of its water content is. The resilient modulus of compacted silt decreases gradually with the increase of its dynamic stress, and decreases linearly with the increase of its water content. Its critical dynamic stress of compacted silt also decreases linearly with the increase of its water content.More>

2009, 9(2): 28-31. doi: 10.19818/j.cnki.1671-1637.2009.02.006

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Effect of lining thickness lack on lining safety for highway tunnel

WANG Hua-lao, LI Ning, CHU Fang-ping

Abstract: The calculation models of lining thickness lack were set up for surrounding rock Ⅲ and rock Ⅳ. The internal forces and safety factors of tunnel lining at various locations were compared under the conditions of tunnel linings with disease and without disease. Using numerical methods, the effect of lining thickness lack caused by disease extent and range on lining safety were analyzed. Analysis result shows that the values of the bending moments, shears and axial forces at the wall, haunch and vault of lining are large, so these sections are belonging to the sensitive parts to disease. When thickness lack disease appears, the safety factor of tunnel lining significantly reduces. With the increase of disease degree, the safety factor of left wall linearly decreases, but the safety factors of haunch and vault curvily reduce. With the increase of disease width, the safety factor firstly decreases obviously and then increases in small range, but the overall trend is decrescent. With the transfer of disease region from wall to vault, the influenced region of lining increases gradually.More>

2009, 9(2): 32-38. doi: 10.19818/j.cnki.1671-1637.2009.02.007

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Shrinkage and creep effects of long-span simple-supported-to-continuous box girder bridge

ZHOU Xu-hong, QIAO Peng, DI Jin, LU: Zhong-da, CUI Ting

Abstract: The stress distributions and deformations of long-span simple-supported-to-continuous box girder bridge during different construction stages were calculated by bar finite element models. The influence of prestressed bar's second-time stretching on shrinkage and creep effects was studied. Taking the 6×70 m continuous box girder bridge as an example, according to different types of calculating methods, including the original algorithm of aging theory, the modified algorithm of aging theory, the algorithm in the annex of JTJ 023—85 Code and the algorithm in the annex of JTG D62—2004 Code, the influences of shrinkage and creep effects on the stresses and deformations of box girders during simple-supported stage and continuous stage were compared. Computational result shows that the maximum influencing discrepancies of stresses at mid spans and supporting points are within 15%, and the maximum influencing discrepancies of deflections at the mid-sections of end span, side span and midspan are separately 36%, 79% and 54%. The deflection calculated by the algorithm in the annex of JTJ 023—85 Code is smallest, while that calculated by the algorithm in the annex of JTG D62—2004 Code is biggest and also is closest to the actual measured value. It's confirmed that the theoretic analysis of shrinkage and creep effects is reliable.More>

2009, 9(2): 39-44. doi: 10.19818/j.cnki.1671-1637.2009.02.008

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Calculating models of time-dependent reliability for existing reinforced concrete beam

ZHENG Yi, LIU Ming, SHEN Xiao-jun, ZHANG Yan-nian

Abstract: The current theory of time-dependent reliability for existing structures and the calculating formula in current standard were analyzed. Considering the condition of material strength deterioration with time and the damages of concrete and steel, time-dependent strength calculating models were built for single-side reinforced concrete beam with rectangular section, double reinforced concrete beams with rectangular section and T-shape section. The time-dependent reliability index was put forward, and an engineering example was studied. Analysis result shows that the reliability index of existing reinforced concrete beam is 1.56, its bearing capacity belongs to grade d and is fit with current reliability appraisal standard, so the calculating models are correct and reasonable.More>

2009, 9(2): 45-49. doi: 10.19818/j.cnki.1671-1637.2009.02.009

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Review of auxiliary braking technologies of commercial automobile

HE Ren, SHEN Hai-jun, YANG Xiao-jun

Abstract: In order to improve the service life and braking ability of main brake for commercial automobile during frequent or prolonged braking, engine brake, exhaust brake applied to diesel engine automobile and eddy current retarder, permanent magnet retarder, hydraulic retarder applied to general automobile were introduced based on the analysis of their structures and working principles. The key technologies on improving braking torque and heat dissipation performance, reducing hysteresis drag torque and matching optimization with whole automobile were studied. The ability evaluation indexes about rated braking torque, average braking torque, thermal decay coefficient and so on were presented. It is pointed that self-excited retarder, integrated retarder and retarder united control will become the development trend of auxiliary braking technologies for commercial automobile, and policy formulation and the protection of intellectual property rights will effectively promoted the development of Chinese auxiliary braking technologies. 10 figs, 17 refs.More>

2009, 9(2): 50-59. doi: 10.19818/j.cnki.1671-1637.2009.02.010

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Influence of velocity change on handling and stability of vehicle

CHEN Shi-an, GU Bin-bin, QIU Feng, HE Ren, LI Chun

Abstract: To improve the handling and stability of vehicle while velocity changing, a dynamic steering model was established, and all of the coefficients of differential equations describing the model changed with velocity change. The influence of velocity change on the handling and stability was quantitatively researched by varying parameter dynamic simulations. Study result shows that when vehicle decelerates, part load is transferred from rear axle to front axle caused by the positive longitudinal inertial force of vehicle, the corner stiffness of front axle increases, the corner stiffness of rear axle decreases, and vehicle steering gain increases, so the handling and stability of vehicle deteriorate. Vehicle steering gain increases more rapidly and obviously with higher early velocity and/or bigger deceleration. When vehicle accelerates, part load is transferred from front axle to rear axle caused by the negative longitudinal inertial force of vehicle, the corner stiffness of front axle decreases, the corner stiffness of rear axle increases, and vehicle steering gain decreases. Obviously, avoiding big deceleration, lowing vehicle mass center and enlarging wheelbase as far as possible during vehicle design and manufacture are effective methods to lessen the degree that the handling and stability become worse rapidly in slowing vehicle down.More>

2009, 9(2): 60-65. doi: 10.19818/j.cnki.1671-1637.2009.02.011

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Aerodynamics properties of high-speed train in strong wind

LI Xue-bing, YANG Zheng, ZHANG Ji-ye, ZHANG Wei-hua

Abstract: Based on the 3D steady incompressible Navier-Stokes equation and the turbulent model of k-ε two equations, the aerodynamics properties of electric multiple units(EMU) CRH-2, running at 200 km·h^-1 in strong wind, were numerically simulated by finite volume method(FVM). The constitutions of aerodynamic force and the influence of yaw angle on flow structure were analyzed, and the composings of aerodynamic force were studied. It is found that flow structure is very complex. Vortices emerge at both the leeward and tail of train on the condition of side wind. The vortices, which are formed and detached in the surface of train, change according to the variation of yaw angle. The constitutions and magnitudes of aerodynamic forces are different for whole train, first car, second car and third car. The variations of pressure field, side force and lift force along the fore-and-aft of train are uniform and complex. Analysis result indicates that the pressure has big influence on side force and lift force. The drag force is primary made of viscous forces for the streamlined design of train. On the condition of side wind, the security of first car decreases because the side force and overturn moment of first car are larger. 5 tabs, 12 figs, 16 refs.More>

2009, 9(2): 66-73. doi: 10.19818/j.cnki.1671-1637.2009.02.012

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Fuzzy control of lateral semi-active suspension system for high-speed train

DING Jian-ming, CHEN Chun-jun, LIN Jian-hui, CHEN Zhe-ming, LIU Hai-quan

Abstract: In order to reduce the lateral vibration of high-speed train caused by shaking movement, a fuzzy control structure of lateral semi-active suspension system was designed. Fuzzy control strategy was adopted to independently control the adjustable shock absorber of suspension system based on double-loop feedback inputs, which were the actual damping force of the shock absorber and the lateral vibration accelerations of the frame and the body for train. With the 17 DOFs vehicle dynamics model that can reflect the lateral vibration features of suspension system, in the input condition of the sixth track spectrum of America and 270 km·h^-1, the lateral vibrations and shaking vibrations of semi-active suspension system and passive suspension system were computed and compared. Computation result shows that stationary indicator improves by 12.54%, shaking vibration reduces by 35.00%, lateral vibration reduces by 48.45%, and the shaking and lateral vibrations of the body are isolated by 50% in the vicinity of natural frequency(1~6 Hz) for the body. The result indicates that the control strategy and control structure can strikingly isolate the lateral vibration of the body. 7 tabs, 6 figs, 9 refs.More>

2009, 9(2): 74-78. doi: 10.19818/j.cnki.1671-1637.2009.02.013

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Terrain trafficability estimating system of off-road vehicle based on virtual proving ground technology

PANG Han, ZHANG Wei-gong, WANG Xia, GUO Zhan-jun

Abstract: In order to estimate the terrain trafficability of off-road vehicle, an estimating system was constructed based on VPG (virtual proving ground) technology. The linear relations of the pressure, stiffness and the effective contact area of tire were analyzed, and the viscoelasticity model of tire was improved with experiment coefficients. The stiffness and damp model of suspension was studied, and a 6 DOF model of off-road vehicle was established based on multi-body dynamics. Six-dimension wheel force transducer and machine vision measure method were employed in experiment demarcating and verifying system to measure force and displacement. The interferential error between experiment result and simulation result for terrain trafficability is less than 5%, so the system is feasible.More>

2009, 9(2): 79-82. doi: 10.19818/j.cnki.1671-1637.2009.02.014

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Transportation analysis of Chinese expressway network in 2007

CHEN Yin-san, XIAO Run-mou, QIN Hua-rong

Abstract: Based on the databases of expressway toll system and sample survey in toll station, the transportation state of Chinese expressway network in 2007 was analyzed. Analysis result showed that the density of freight traffic in expressway network rose by 12.30% in the same period in 2006. The passenger traffic density of mini-type buses(the seat amount of every bus is less than 8) rose by 18.90%. 66.20% of freight turnover volume was produced by tractor-trailer combinations. The percentage of empty truck kilometers to loaded truck kilometers was 18.97%. The percentage of trucks whose overweight was more than 30% was 6.81%, 38.12% of passenger turnover volume was produced by mini-type buses. Average passengers carried by per car were 2.50. The characteristic of transportation in Chinese expressway network was that the proportion of freight traffic is higher. Vehicle kilometers completed by trucks accounted for 37.52% in total vehicle kilometers. This situation aggravated loads on road, and facilitated accidents, especially on montane expressways. In 2007, passenger transport market formed by large sized and medium-sized passenger cars in expressway network was pressed by railway transportation, and this situation will continue in the next few years.More>

2009, 9(2): 83-88. doi: 10.19818/j.cnki.1671-1637.2009.02.015

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Complexity measure of traffic flow time series

ZHANG Yong, GUAN Wei

Abstract: In order to quantitatively analyze traffic flow complexity, the Kolmogorov complexity(Kc) and the approximate entropy(ApEn) were adopted, the system periodic ingredient ratio was estimated by using the Kc of speed time series, and the Kc evaluation ability was improved by dividing reconstructing time series into more sectors. In the ApEn computation, the time series of speed change rate was got to remove the tendency of speed time series, then the complexity of system structure change was estimated by using the ApEn of speed change rate series. Calculation result of real traffic flow time series shows that the Kc can be obtained when the time series is longer than 600, and the ApEn can be got when the time series is longer than 300. The Kc and ApEn of traffic flow are lower on synchronization condition, increase on jam condition, and are largest on free condition. So the Kc and ApEn adapt to definite traffic condition, the Kc can be used to analyze longer-term traffic flow series, but the ApEn can be used to analyze shorter-term traffic flow series.More>

2009, 9(2): 89-92. doi: 10.19818/j.cnki.1671-1637.2009.02.016

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Change rate models of equivalent queue length for congested traffic flow

YAO Rong-han, WANG Dian-hai

Abstract: In order to describe the evolution rules of vehicle queue in congested traffic flow, the equivalent queue length change rate models for single-lane and multi-lane links were educed by calculous method on the basis of equivalent queue length models from two-fluid theory. These models were validated by the simulated data from VISSIM. Analysis result indicates that the equivalent queue length change rate is approximately equal to traffic wave velocity when traffic flow is at congested state. The equivalent and actual queue length change rates approach in sampling interval. Error method and entropy method are used to prove that they more approach when sampling interval is longer. So these models can quantitatively describe the evolution speed of vehicle queue in congested traffic flow.More>

2009, 9(2): 93-99. doi: 10.19818/j.cnki.1671-1637.2009.02.017

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Evaluating experiment of driving tensity

WU Hua-jin, GUO Hai-long, YUAN Wang-fang, WEI Lang

Abstract: In order to study the effect of road condition on diver's tensity, the test indexes including heart rate, moving speed of eyeball and gazing area were chosen. Through multi-condition and multi-type-vehicle tests with 33 drivers, the data of the indexes from electrocardiograph and eye tracker were collected and analyzed, the membership functions were established to evaluate the degrees that the indexes belonged to no tension area, some extent tension area and great tension area. On the condition that vehicle speed was 80 km·h ^-1 and lateral clearance was 1.2 m, the membership degrees of heavy-vehicle drivers were calculated. Experiment result shows that the membership degrees of large-vehicle drivers belong to some extent tension area, the membership degrees of medium-vehicle drivers belong to great tension area, which is consistent to the drivers' safety perception of practical road-vehicle test.More>

2009, 9(2): 100-104. doi: 10.19818/j.cnki.1671-1637.2009.02.018

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Cognitive regulation of space distance about drivers to genial tone obstacles in daytime dynamic environment

LIU Hao-xue, ZHAO Wei-hua, LIU Kai-zheng, ZHANG Juan, ZHOU Jing

Abstract: The cognition data of absolute distances and relative distances for 32 drivers who were selected randomly, were obtained and disposed through statistic and regress analysis. The quantitative variation laws about cognitive distances to genial color tone obstacles were studied in ground dynamic environment. Six cognitive mathematical models about absolute and relative space distances under the conditions of three different distances that are 25, 75, 125 m were established. Analysis result shows drivers' cognition accuracy for absolute distance in depth direction decreases with the increase of actual distance, and the accuracy of relative distance cognition is higher than that of absolute distance cognition. With the increase of vehicle velocity, the accuracy of distance cognition declines continuously, and there is a negative exponential relationship between cognitive distance and vehicle velocity. The minimum correlative coefficient of the models is 0.941, so they are feasible.More>

2009, 9(2): 105-109. doi: 10.19818/j.cnki.1671-1637.2009.02.019

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Integrated control model of urban expressway off-ramp and correlative intersection

YANG Xiao-fang, HAN Yin, FU Qiang

Abstract: In order to keep the queues of intersection and off-ramp from backupping to expressway mainline, an integrated control model of off-ramp and correlative intersection was proposed based on cell transmission model(CTM). When overfull queue appeared at off-ramp, red truncation strategy or green extension strategy was adopted. When overfull queue did not appear at off-ramp, the cycle and green signal ratio of intersection were optimized dynamically to minimize the average vehicle delays of off-ramp and correlative intersection. Simulation result shows that the vehicle average delay of correlative intersection increases by 1.74 s, but the queue decreases from over 200 m to 160 m, so the strategies and model are reasonable and effective.More>

2009, 9(2): 110-115. doi: 10.19818/j.cnki.1671-1637.2009.02.020

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Design and implementation of traffic monitoring system based on SAS and IEEE1451

LI Zi-qing, GONG Da-li

Abstract: In order to solve the interface compatibility problem of various sensors and actuators used in traffic control system, an opening, plugging and playing intelligent traffic monitoring system was developed based on sensor agent server(SAS)theory and IEEE1451 intelligent sensor interface standards. With IEEE1451.2 and IEEE1451.4 interface standards, the intelligent front-parts of the monitoring system, including data acquisition system, smart sensor modules, network interface circuit and TEDS programme, were designed and implemented. An application programme was developed. The real-time data communication between PC and data acquisition system was completed via USB2.0 standard port. Experiment result shows that the system has better running stability and strong real-time performance.More>

2009, 9(2): 116-120. doi: 10.19818/j.cnki.1671-1637.2009.02.021

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Service level evaluation of signalized intersection based on trapezoid whitenization weight function

LIU Jun-juan, WANG Wei, CHENG Lin

Abstract: The connotation and extension of service level for signalized intersection were analyzed, grey number was adopted to express the evaluation indices and clustering thresholds by using grey clustering idea. Grey number formula and clustering model were built based on trapezoid whitenization weight function. A revised method was given to determine grey number value and was approximately described by 3σ and 1.23σ principles of normal distribution in view of the traffic characteristics of signalized intersection. The service levels of 3 signalized intersections were evaluated by using the model. Analysis result shows that maximum clustering values of intersection A1, A2 and A3 are respectively [0.416, 0.839], [0.202, 0.728] and [0.413, 0.645], the grades of service levels form high to low are A1, A3 and A2, so clustering model and grey number formula are reasonable and effective.More>

2009, 9(2): 121-126. doi: 10.19818/j.cnki.1671-1637.2009.02.022

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