2010 Vol. 10, No. 5

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Numerical simulation of biaxial test for granular materials based on discrete element method
CHANG Ming-feng, PEI Jian-zhong, CHEN Shuan-fa
Abstract: In order to obtain the relationships between the mechanics parameters of granular materials and test conditions, discrete element method(DEM)was applied to prepare the initial specimens and simulate the biaxial test of granular materials with five particle diameters.The influences of different confining pressures on the elastic moduli, the strengths and the variation rules of elastic moduli, the Poisson's ratios and the strengths under different loading velocities were analyzed.The stress-strain curves of five specimens were plotted under confining pressure of 10 MPa and loading velocity of 0.03 m·s-1, and the crack distributions in the specimens were also given from microscopic viewpoint.Simulated result indicates that the elastic moduli and strengths of five specimens increase with confining pressures, and the increasing trends are relatively smooth.However, the specimen with 9.50~13.20 mm particles has a bigger fluctuation.The relationships between loading velocity and the elastic modulus, the Poisson's ratio, the strength and the crack-initiation stress are quadratic polynomials basically, the minimum correlation coefficient is 0.900 9, and the maximum correlation coefficient is 0.995 9.In addition, the peak values of stresses obtained from stress-strain curves reduce with the increase of particle diameters.More>
2010, 10(5): 1-7. doi: 10.19818/j.cnki.1671-1637.2010.05.001
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Combined evaluation method of slope stability
LI Wei
Abstract: With MATLAB optimization toolbox, the parameter variability of soil was considered, the reliability index and corresponding safety factor of slope were computed by using response surface method(RSM)with quadratic sequence, and the safety factor was reduced by using the corresponding failure probability of the reliability index. A combined evaluation method, named reliability index and reduction safety factor evaluation method, was set up, the stability of slope was evaluated, and the calculation result and the failure surfaces obtained by the method were compared with the results obtained by traditional certification method and median reduction method of safety factor in dual index method. Comparison result indicates that slope may be unreliable with a safety factor(greater than 1)calculated by using traditional method when the parameter variability of soil is larger. In the present method, the reliable part of the safety factor is gotten by the reducing process, simultaneity, the unreliable part resulted from ignoring the uncertainty is deleted, so it can give a reasonable evaluation for practical slope.More>
2010, 10(5): 8-11. doi: 10.19818/j.cnki.1671-1637.2010.05.002
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Numerical simulation of soil pressure and deformation for culvert with load-reducing measures
GUO Ting-ting, GU An-quan
Abstract: Based on the test sites of two culverts on Nanguang Expressway, EPS(expanded polystyrene)was taken as load-reducing material, the vertical soil pressures and soil deformations of the culverts under the conditions with and without load-reducing boards were studied and compared by ANSYS simulation and measure, and the influence of the thickness of EPS boards on the pressures and deformations was analyzed. Analysis result shows that under maximum soil-filling height, the differences between the calculated values and measured values of the pressures are not more than 16%. When EPS boards are laid on the tops of the culverts, the pressures of the culverts decrease by about 1/2~2/3. Under experimental condition, the thicker EPS boards are, the better the load-reducing effect is. The deformation nephograms of soil intuitively show the existence of settlement difference between inside and outside soil columns on the tops of the culverts, and it is an integrated parameter that can reflect the various influence factors of the pressures. When EPS boards are laid on the tops of the culverts, the forming settlement difference results in the load-reducing effect of EPS boards. Under the same soil-filling height, the thicker EPS boards are, the bigger the settlement difference is, the better the load-reducing effect is.More>
2010, 10(5): 12-16. doi: 10.19818/j.cnki.1671-1637.2010.05.003
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Reynolds number effect of streamlined bridge section
BAI Hua, LI Jia-wu, CUI Xin, LIU Jian-xin
Abstract: The three-component force coefficients of streamlined sections of Sutong Bridge with different Reynolds numbers were calculated by using numerical simulation. The Reynolds number effect of streamlined section for bridge model with chord/thickness ratio of 10∶1 was investigated by wind tunnel test, the influence of Reynolds number on drag coefficient, surface pressure coefficient, wind pressure spectrum and Strouhal number was analyzed, and the restraining action of surface roughness on Reynolds number effect was researched. It is pointed that drag coefficient decreases with the increase of Reynold number. The zero position of surface pressure coefficient is subject to the influence of Reynolds number. Strouhal number exists platform effect because of the influence of Reynolds number. Strouhal number measured by wind tunnel test with low Reynolds number decreases by 20% compared with the one of practical bridge. Reynolds number effect of streamlined section is considerable. Surface roughness can restrain Reynolds number effect.More>
2010, 10(5): 17-22. doi: 10.19818/j.cnki.1671-1637.2010.05.004
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Whole rigidity characteristic of T-beam bridge under random traffic flow
SUN Sheng-jiang, XU Jian-wei, HAN Wan-shui, MEI Kui-hua
Abstract: ANSYS program was used to establish the space bar element models of T-beam bridges with three different transverse connections, such as hinging, wet seaming and wet seaming with integral layer.The load spectrum of random traffic flow was programmed.Bridge dynamic analysis system(BDANS)was used to calculate the dynamic deflection of T-beam bridge under random traffic flow, and its whole rigidity characteristic was analyzed.The result shows that the rule of transverse distribution of dynamic response is consistent with that of static reaction.The dynamic response of every beam for T-beam bridge with hinging connection is very different, which shows that its whole rigidity is worst.Its maximum deflections under various traffic operations are 1.30 times larger than those with other two connections, and can reach 2.02 times as much as those under regular one-lane traffic operation.The dynamic response of every beam for wet seaming connection and wet seaming connection with integral layer is similar.Therefore, the whole rigidities of T-beam bridges with the latter two connections increase evidently.More>
2010, 10(5): 23-29. doi: 10.19818/j.cnki.1671-1637.2010.05.005
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Dynamics analysis of 25 t axle load steering bogie with radial arm
YANG Chun-lei, LI Fei, FU Mao-hai, HUANG Yun-hua
Abstract: On the basis of the theory of vehicle-track coupling dynamics, the structural and forced features of 25 t axle load steering bogie with radial arm were analyzed, a freight car-track coupling dynamics model was set up, and the lateral stability and the dynamics performances of rectilinear running and curve negotiation of the car were simulated to compare with conventional three-piece bogie. It is pointed that the lateral stability of conventional three-piece bogie with radial arm increases by above 10%, wheel-track abrasion decreases by above 40%, and wheel-track force decreases by above 20%.More>
2010, 10(5): 30-37. doi: 10.19818/j.cnki.1671-1637.2010.05.006
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Influence of partial load on riding quality of vehicle
CHI Mao-ru, ZHANG Wei-hua, ZENG Jing
Abstract: A mathematic model of partial load vehicle was set up. As an example of a high-speed vehicle running on tangent track with Germany low-disturbing spectrum at 300 km・h-1, the influences of all kinds of partial loads on the riding quality of vehicle were analyzed and compared by simulation. Analysis result shows that with the increase of partial load, the riding quality of vehicle is getting worse, longitudinal partial load has larger influence on the riding quality between the foreside and backside of vehicle, and lateral partial load has less influence on them. So in order to improve the riding quality of vehicle, partial load must be minished by all means, especially, longitudinal partial load must be strictly controlled. 5 figs, 10 refs.More>
2010, 10(5): 38-41.
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Influence of partial load on riding quality of vehicle
CHI Mao-ru, ZHANG Wei-hua, CENG Jing
Abstract: A mathematic model of partial load vehicle was set up. As an example of a high-speed vehicle running on tangent track with Germany low-disturbing spectrum at 300 km·h-1, the influences of all kinds of partial loads on the riding quality of vehicle were analyzed and compared by simulation. Analysis result shows that with the increase of partial load, the riding quality of vehicle is getting worse, longitudinal partial load has larger influence on the riding quality between the foreside and backside of vehicle, and lateral partial load has less influence on them. So in order to improve the riding quality of vehicle, partial load must be minished by all means, especially, longitudinal partial load must be strictly controlled.More>
2010, 10(5): 38-41. doi: 10.19818/j.cnki.1671-1637.2010.05.007
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Simulation of energy-saving driving mode during steering for motorized wheels driving vehicle
ZHANG Huan-huan, JIN Li-qiang, WANG Qing-nian
Abstract: In order to study the energy consumption feature of motorized wheels driving vehicle during steering, the resistance force was analyzed when the vehicle ran on curvy road, and a energy-saving mode of quasi-neutral steering was proposed. A simulation model of the vehicle was established by using MATLAB/Simulink, the yaw rate was taken as the control variable to control the front-rear torque distribution coefficient with PID, the lateral acceleration was taken as the control variable to control the left-right torque distribution coefficient with PID, and the steering condition at constant speed was simulated. Simulation result indicates that in the mode, no wheel slipping happens, the torque of rear-outer wheel is maximal, the torque of outer wheel is larger than the torque of inner wheel, the torque of rear wheel is larger than the torque of front wheel, and the power consumption decreases by 1.15%.More>
2010, 10(5): 42-46. doi: 10.19818/j.cnki.1671-1637.2010.05.008
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Loading deformation characteristic of renovation tire
QI Xiao-jie, WANG Qiang, YU Jian-guo
Abstract: Considering the main structure and combined performance of multiple composites for renovation tire, the mechanics model, geometric model and finite element model of renovation tire for 11R22.5 loading vehicle were set up, the simulation analysis and experimental research of its deformation characteristics were conducted by using composite laminated structures and finite element large deformation theory, and the same brand and same model new tire was compared. The deformation theory formula of renovation radial tire was amended based on the loading deformation characteristic rules of renovation tire. Analysis result indicates that when inflation pressure is certain, the radial deformation, lateral deformation, grounding length and contact area of renovation tire increase with load increase, its deformations are almost linear, while its radial stiffness hardly changes. When load is certain, the radial deformation, lateral deformation, grounding length and contact area decrease with inflation pressure increase, while its radial stiffness increases. The elastic modulus of renovation tire's carcass is bigger than the one of new tire's carcass. The greater the modulus difference between the two carcass is, the higher the aging degree of renovation tire's carcass is, the lower its remaining service life is, which benefits for predicting the aging properties of renovation tire's carcass.More>
2010, 10(5): 47-56. doi: 10.19818/j.cnki.1671-1637.2010.05.009
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Dynamic hydroplaning analysis of car tire
JI Tian-jian, GAO Yu-feng, CHEN Rong-sheng
Abstract: The dynamic hydroplaning of car tire was studied by the theory of elastohydrodynamic lubrication. The system of elastohydrodynamic lubrication was made of tire, water on pavement and pavement. The coordinate system was set up on tire, so tire was relatively immobile, and water film was relatively mobile. To control the hydroplaning, the equations of Reynolds, thickness of water and its distortion were derived. The equations were solved by using complex direct iteration algorithm and corresponding program. Computation result indicates that the thickness of water film on pavement that can lead to the hydroplaning becomes lessening with speed increase. The hydroplaning will happen when the speed of car is 120 km·h-1 and the thickness of water film on pavement is 2 mm.More>
2010, 10(5): 57-60. doi: 10.19818/j.cnki.1671-1637.2010.05.010
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Dual-objective reliable network design based on particle swarm optimization
CHEN Ling-juan, PU Yun
Abstract: A bi-level programming model of network design was established by supposing the capability of road section to be a discrete random variable. The upper model was a dual-objective programming model, which considered the minimum of network expected travel time and the maximum of network net ecoromic benefit reliability. The lower model was a user equilibrium(UE)with elastic demand. The excess-demand formulation was adopted to solve the lower model, and the vector evaluated particle swarm optimization(VEPSO)was adopted to solve the whole bi-level programming. Analysis result indicates that the outcome is a group of Pareto solutions, network expected travel time and network net economic benefit reliability are contradicting objectives. Network expected travel time decreases, the reliability also decreases. When the reliability keeps invariant, total investment amount increases with the decrease of expected travel time. The optimum scheme for network design should be chosen by combining total investment amount with actual situation.More>
2010, 10(5): 61-65. doi: 10.19818/j.cnki.1671-1637.2010.05.011
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Application of GIS and multiple attribute decision theory in highway runway locating
ZHANG Luo-li, CAI Liang-cai, ZHONG Xiao-lei, DU Yi-lin, WANG Xiao-hui, ZHANG Zhong-ling
Abstract: The influencing factors of construction, use and safeguard for highway runway were analyzed, and the evaluating index system of highway runway locating was brought out.The functions of information management and spatial analysis for highway network GIS were used, and the sample set of feasible locations for highway runway was obtained.The attribute weights of the factors were ascertained by establishing multiple attribute decision model and using optimization theory, and the check-up values of alternatives and the best scheme were gotten.The method of selecting site was examined with an example.Analysis result indicates that the check-up values of four alternatives are 0.022 6, 0.084 3, 0.015 8, 0.022 9 respectively, the best one is scheme 3, which accords with fact, so the method is available.More>
2010, 10(5): 66-70. doi: 10.19818/j.cnki.1671-1637.2010.05.012
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Simulation model and algorithm of multi-runway airport gate assignment
YIN Jia-nan, HU Ming-hua, ZHAO Zheng
Abstract: Based on the traditional ideas of taxiway routing and gate waiting, a simulation model was proposed for multi-runway airport gate assignment problem. With security constraints, the model minimized total taxiing time to find out optimal assignment. On the basis of multi-runway airport informations such as ground network data, operating mode and flight schedules, a gate assignment simulation algorithm was designed and applied to real-time surface operations. Simulation result shows that compared with random assignment algorithm, the ground capacity increases by 4.6%, the times of conflict detection and resolution decrease by 10.7%, and the maximal delay reduces by 34.8%. So the efficiency of airport surface traffic is improved, and the proposed algorithm is feasible.More>
2010, 10(5): 71-76. doi: 10.19818/j.cnki.1671-1637.2010.05.013
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Impact of uncertainty on traveler route choice in urban traffic
ZHANG Yang
Abstract: To study the impact of travel time uncertainty on traveler route choice in urban traffic, a hypothesis that travelers took aversion to travel time uncertainty was presented based on prospect theory. A Bayesian model was used to analyze travelers' behaviors influenced by updating uncertainty perceived in rerouting, and an example was tested by using survey data. Analysis result shows that 77.73% travelers prefer routes with less uncertainty.66.39% travelers change their departure times when the uncertainty of travel time reduces, so that mean travel time budget decreases about 10.03%.70.90% travelers change their departure times when their familiarities with route increase, so that mean travel time budget decreases about 15.56%. So travel time budgets decrease with the decrease of travel time uncertainty and the increase of repeated travels.More>
2010, 10(5): 77-80. doi: 10.19818/j.cnki.1671-1637.2010.05.014
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Parking fee and scale optimization of public parking lot with incomplete information
ZHENG Shi-yuan
Abstract: In order to make planning for the parking fee and scale of public parking lot in the situation of incomplete information, the parking fee and scale optimization models under regulation operation mode and competition operation mode were established. The criteria of optimal parking fee and scale were got, and the affections of different factors on parking fee and scale were analyzed by means of bi-dimensional adverse selection and dynamic game approach. Through the comparison of public parking lot operations and social welfares with two modes, it is known that the effects of different modes on parking fee are uncertain. Compared with regulation operation mode, the optimal scale is 94.21% larger, the private parking company's profit is 67.13% higher, the parking demand is 36.70% larger, and the social welfare is 41.34% higher under competition operation mode. So competition operation mode can benefit the operation of public parking lot and social welfare.More>
2010, 10(5): 81-89. doi: 10.19818/j.cnki.1671-1637.2010.05.015
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Interactive mechanism of cointegration and causality between regional logistics and economic development
CUI Guo-hui, LI Xian-sheng
Abstract: Logistics industry investment, cargo turnover mileage, logistics network density and GDP were taken as studying objects, the methods and models of dynamic econometrics theory were used, the interactive mechanism of cointegration and causality was empirically analyzed between logistics industry and economic development from 1991 to 2007 in Jilin Province. Analysis result shows that Jilin logistics network density on economic development has one-way causality, and economic development on logistics cargo turnover mileage and logistics industry investment has one-way causality from the view of Granger causality test. From the views of cointegration test and error correction model, there is a relatively stable long-term equilibrium development trend between logistics and economics development in Jilin Province, and the fluctuation of deviation in the short term is rectified by the rate of 8.7%.More>
2010, 10(5): 90-96. doi: 10.19818/j.cnki.1671-1637.2010.05.016
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Extended multi-factorial evaluation of coordination development for rural road based on matter-element model
MA Zhong-ying, YANG Qi, ZHOU Wei
Abstract: For the evaluation of development coordination between rural road and regional social economy, the factors affecting the coordinated development were analyzed, and principal component analysis method was used to construct evaluation index system. Based on extension theory and correlation function, a synthetic matter-element evaluation model was constructed, and complex multi-index evaluation was converted to single-objective evaluation. The evaluation of coordination was done by calculating the synthetic correlated degree, and the model was used in Haidong of Qinghai Province. Analysis result shows that the synthetic correlated degree between rural road and regional social economy coordinated develpoment in Haidong is 0.368 7, which is not coordinated state, and it is consistent with the current situation.More>
2010, 10(5): 97-101. doi: 10.19818/j.cnki.1671-1637.2010.05.017
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CKF-based robust filtering algorithm for GNSS/INS integrated train positioning
LIU Jiang, CAI Bo-gen, TANG Tao, WANG Jian
Abstract: Based on the fusion estimation problems of nonlinearity and robustness in integrated train positioning, the principle and architecture of global navigation satellite system/inertial navigation system(GNSS/INS)integrated train positioning system were introduced, the scheme of CKF nonlinear filter approach was given, and a novel CKF-based robust filtering algorithm was presented by applying H∞ robust filter theory to standard CKF frame. The autonomous filter state monitoring was discussed for the proposed algorithm. The filter convergence criterion and the robustness criterion of error's H∞ norm bound were analyzed, and field tests in Qinghai-Tibet Railway were illustrated. Analysis result shows that under field test condition, the average estimation error of the proposed algorithm decreases by 7.13% and 4.85% respectively in comparison with standard UKF and CKF. The root mean square of estimation error increases by 8.56% with constraint level from 31.5 to 1 315.0, so the estimation precision changes mildly, and the algorithm is effective.More>
2010, 10(5): 102-107. doi: 10.19818/j.cnki.1671-1637.2010.05.018
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Acquisition and track algorithm of GPS weak signal
SHANGGUAN Wei, WANG Jing-jing, CAI Bo-gen, WANG Jian, LIANG Qian-hao
Abstract: During the design process of acquisition algorithm for GPS weak signal, in order to increase acquisition sensitivity, a method that combined coherent integration with noncoherent integration was adopted to eliminate the influence of data code length on coherent integration gain, and a differential coherent integration was proposed to reduce the square tenuation in noncoherent integration. Instead of traditional methods, FFT-based code and carrier acquisition algorithm was implemented to improve acquisition speed and accuracy. DLL and PLL were used in GPS weak signal track. Finally, the acquisition and track of GPS weak signal were realized by simulation. The result indicates that it is a good approach to track and capture GPS weak signal with the CNR of 25 dB·Hz-1 by simulation technology. The sensitivity of differential coherent acquisition is 0.8 dB larger than the sersitivity of coherent-noncoherent integration, frequency acquisition error is less than 1.25 Hz, and code acquisition error is less than 0.1 code.More>
2010, 10(5): 108-113. doi: 10.19818/j.cnki.1671-1637.2010.05.019
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Detection method of traffic state for urban traffic network based on wavelet analysis
ZHANG Jing, JU Yong-feng, CHEN Li
Abstract: The import saturation degree of intersection and the average travel speed of road section were selected as the basic parameters of road network's state detection, the high time-frequency properties of wavelet packet transform was adopted, and the mutation and unusual conditions of the saturation and the speed were distinguished by using energy analysis method. In order to describe the change of traffic state, a coefficient was defined, a traffic state detection algorithm was designed by using wavelet analysis, and Bayesian Method was used to predict the traffic state. Simulation result shows that the mutation interval of energy distribution can be identified by using wavelet analysis, based on which the changing time interval of traffic state can be distinguished. While the maximal points of sampling data modulus are from 200 to 243, the energy change of the section node is intense, and the state changes from steadiness to unsteadiness. When the coefficient of traffic state is more than 0.300 h·km-1, a crowded state appears. The method with simple working principle and short time response to congestion is feasible because of its credible detection result.More>
2010, 10(5): 114-120. doi: 10.19818/j.cnki.1671-1637.2010.05.020
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Reconstructive method of missing data for location-specific detector considering spatio-temporal relationship
SUN Ling, LIU Hao, NIU Shu-yun
Abstract: The relationship between the missing data and other data of traffic flow was studied by using correlation theory. A reconstructive method based on spatio-temporal relative weight values was put forward when other data had different correlations with missing data and were given different spatio-temporal relative weight values. The Beijing Expressway of Second Ring Road was selected as test road, its simulation models were established by using VISSIM, and the new method and existing methods were compared by using simulation data. Analysis result shows that the maximum average relative error between the reconstruction values and simulation values of model 1 is only 1.876 6% and below 1.000 0% in general when the numbers of continuous missing data are from 1 to 10, so the method of model 1 is better than existing reconstructive methods.More>
2010, 10(5): 121-126. doi: 10.19818/j.cnki.1671-1637.2010.05.021
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