01 March 2012, Volume 25 Issue 2
    

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  • Field Test on Variable Diameter Deep Mixed Column for Layered Soft Ground Improvement
    LIU Song-yu, YI Yao-lin, DU Yan-jun, JING Fei, GONG Neng-he
    China Journal of Highway and Transport. 2012, 25(2): 1-8.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The variable diameter deep mixing method was proposed so as to economically and efficiently treat a layered soft ground where the soft layer is at the middle depth. A relatively high column area replacement ratio was used for the high compressive soil layer and a relatively low column area replacement ratio was used for the medium compressive soil layer, which could result in a layered composite foundation where the column replacement ratio varied with soil layers. Two testing sections of variable diameter deep mixed column and common mixed column were established on the same site. Field tests were conducted to analyze their engineering performance under embankment load, including stress of column and soil, excessive pore water pressure, ground settlement and lateral displacement under the embankment toe. Field test results show that when the treated site in the areas and embankment heights are similar, the treated section of variable diameter deep mixed column which gets the same consolidation effect can save 14.6% cement than that of the conventional one, and it can be more economically effective than that of the conventional deep mixing method for layered soft ground improvement.
  • Practical Calculation Method for Stability of Embankment on Soft Subgrade Reinforced with Unreinforced Rigid Piles
    ZHENG Gang, LI Shuai, DIAO Yu
    China Journal of Highway and Transport. 2012, 25(2): 9-19.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to reasonably evaluate the stability of embankment supported on composite ground reinforced with unreinforced rigid piles, based on the study of the failure mechanism of embankment on soft subgrade reinforced with rigid piles, different simplified stability analysis methods were suggested and compared with traditional method by performing numerical analysis of three typical examples of embankment. The results indicate that embankment stability can be highly overestimated when using the traditional method and the equivalent shear strength method can better reflect the failure mechanism of embankment reinforced with rigid piles. The safety factors by the equivalent load method and the equivalent sand pile method are fairly close to that by the equivalent shear strength method. The pile-soil stress ratio has great influence on the safety factors with the BS 8006 method, the equivalent load method and the friction contact method. It is suggested that more than one simplified method be used when performing the overall stability analysis for embankment supported on composite ground reinforced with unreinforced rigid piles in order to ensure the redundancy of the design.
  • Research on Improvement Technology of Filling Subgrade with Highly-weathered Phyllite
    MAO Xue-song, ZHOU Lei-gang, MA Biao, ZHENG Xiao-zhong, ZHAO Wen-yi
    China Journal of Highway and Transport. 2012, 25(2): 20-26.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In the area with lots of highly-weathered phyllites that the mountainous expressway run through, to solve the problems of the shortage of filling soil and using farmland soil or deserted soil from other places, and to protect the environment and save investment, the in-situ highly-weathered phyllites were applied as the filling material instead of the general soil. Based on both the physics and mechanics experiments and the engineering characteristic experiments of the phyllites, different contents cement was mixed into the phyllites to form a new kind of filling material. The material could satisfy the requirement of the highway standard through mixing the cement. The compaction performance, the graduation characteristics and the engineering characteristics of the filling material under different cement contents were analyzed. The test road being from section K22+720 to section K22+920 of Shiyan-Tianshui Expressway were selected to validate the feasibility of the reinforcement technology. The contents of mixing cement were from 3% to 6% at interval of 1%. The results show that the mechanics performance of the filling material can be reinforced by mixing the cement into the phyllites and can satisfy the requirement of the highway standard. With the increase of the mixed cement content, both the CBR value and the modulus of the filling material increase.
  • Preparation and Performance of PAN-based Carbon Fiber Conductive Asphalt Concrete
    FENG Xin-jun, ZHA Xu-dong, CHENG Jing
    China Journal of Highway and Transport. 2012, 25(2): 27-32.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to prepare conductive asphalt concrete for melting ice and snow on road surface, preparation and performance of PAN-based carbon fiber conductive asphalt concrete were studied. Through resistivity test of Marshall specimen, chopped length of PAN-based carbon fiber was determined. After the mixing test and Marshall compaction test of asphalt mixture, mixing techniques of PAN-based carbon fiber conductive asphalt concrete was put forward.The optimal oil-stone rate of PAN-based carbon fiber conductive asphalt concrete was determined with Marshall test design method, and the technical standards were adjusted according to their structural characteristics. Through tests of resistivity, rutting, trabecular bending, immersion Marshall and freezing-thawing splitting, variation laws of conductive properties and pavement performance with PAN-based carbon fiber quality fraction of conductive asphalt concrete were analyzed. The results show that conductive asphalt concrete with 0.1% PAN-based carbon fiber quality fraction has excellent conductive properties and pavement performance.
  • Study of the Toughness of Fiber Reinforced Concrete Pavement in Laboratory
    LIU He, FU Zhi, LIU Yi-han
    China Journal of Highway and Transport. 2012, 25(2): 33-39.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to get the load-deflection curve of fiber reinforced concrete (FRC), and study the fibers' influence on the toughness of FRC, 8 groups of FRC were molded and tested. The test data were obtained by data acquisition device which could generate load-deflection curve. The effect of fiber type and content on the FRC toughness index were analyzed, and the relation between toughness index and flexural strength were studied. The results show that steel fiber makes a great contribution to flexural strength. Mill-cut steel fiber works well with imitation wire polypropylene fiber in FRC, and the toughness index of the acicular steel fiber reinforced concrete increases with the increase of fiber contents. The toughness index increases with the increase of number and volume percentage of fiber, but the high toughness index specimen may not have the high flexural strength, and flexural strength 6.7 MPa corresponds to the minimum toughness index.
  • Research on Basic Performance of Composite Bridge Deck System with Orthotropic Steel Deck and Thin RPC Layer
    SHAO Xu-dong, CAO Jun-hui, YI Du-tao, CHEN Bin, HUANG Zheng-yu
    China Journal of Highway and Transport. 2012, 25(2): 40-45.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to deal with the problems of damage in orthotropic steel deck and fatigue crack in steel deck structure, an innovative composite bridge deck system with orthotropic steel plate and thin reactive powder concrete (RPC) layer was presented. Finite element models were established on the basis of a certain bridge. Pure steel girder and composite girder were created respectively to compute tension force in the main cable and stress state in bridge deck system. Then, static load experiment of full-scale composite beam model was carried out. The results show that tensile stresses in steel deck decrease obviously when the innovative steel-RPC composite deck system is adopted and the maximal reducing amplitude is over 70%. But the tensile force in main cable can hardly increase. Tensile stress of the RPC layer is up to 42.7 MPa before tiny cracks appear, which is much greater than 10.08 MPa in calculation. Stiffness of original orthotropic steel deck can be improved by the composite bridge deck system. Consequently, stress in orthotropic steel deck decreases greatly, which will effectively eliminate the risk of fatigue cracking in steel deck.
  • Experiments on the Mechanical Properties of Corrugated Rib Connector
    SU Qing-tian, WANG Rui, WANG Wei
    China Journal of Highway and Transport. 2012, 25(2): 46-52.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To research and develop a new type of connector for steel and concrete composite structure, a new type of connector, corrugated rib connector, was developed. Three push-out tests with corrugated rib connector and three push-out tests with perfobond rib connector were carried out. The basic mechanical properties of these connectors were measured and the test results were compared and analyzed. The load-slip relation of corrugated rib connector was obtained, and relative stiffness expressions under normal service state and ultimate bearing capacity state were fitted. The test result shows that the mechanical properties of this connector are excellent. The shear strength of corrugated rib connector is 24 percent greater than that of the perfobond rib connector, and the shear stiffness of corrugated rib connector is larger than that of the perfobond rib connector. Besides, the ductility of corrugated rib connector is 1.9 times higher than that of the perfobond rib connector when they reach the ultimate load.
  • Research on Seismic Damage Evaluation of CFST Arch Bridges
    XIE Kai-zhong, LU Wen-gao, QIN Le-qin, MENG Fang-cheng
    China Journal of Highway and Transport. 2012, 25(2): 53-59.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the seismic damage conditions of concrete filled steel tube (CFST) bridge from the internal force, deformation and energy, the damage indexes (DI) of all the members were calculated. The evaluation model of the bridge was established and the seismic damage evaluation method of CFST arch bridge was presented. In the research, the internal forces, deformations and accumulated energy of CFST arch bridge were analyzed by numerical simulations under dead load and earthquake, and the seismic damage of CFST arch bridge was evaluated with the example of Nanning Yonghe Bridge. The results show that for the 7-degree seismic fortification intensity zone, the bridge is in perfect condition under 8-degree earthquake and there is only slight damage under 9-degree earthquake, which indicates that the bridge can meet the demands of seismic fortification.
  • Fatigue Reliability Analysis on Cable of Cable-stayed Bridge Under Random Vehicle Load and Wind Load
    LI Yan, LU Da-gang, SHENG Hong-fei
    China Journal of Highway and Transport. 2012, 25(2): 60-66.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking a long span cable-stayed bridge as a project background, the fatigue reliability of cable stay in combination as random vehicle load and wind load was analyzed. The authors firstly, setup traffic and wind load probability models for the bridge based on the traffic survey data and long-term wind velocity data from bridge site; then calculated the stress spectrum of the cable stays under combining loads by running self-compiled wind-vehicle-bridge interaction dynamic response analysis program; finally, evaluated the fatigue reliability and fatigue life with help of cumulative damage theory and Monte-Carlo method. The result shows that the effect of wind load on the fatigue reliability of cable stay is significant, and the influence degree increases in accordance with the order from short cable to long cable. Compared with only vehicle load, the fatigue life of the cable under both vehicle and wind load decreases by the range from 2% to 63%, with an average ratio of 50%.
  • Study of Longitudinal Stiffness of Middle Pylon in Multi-span Suspension Bridge
    CHAI Sheng-bo, XIAO Ru-cheng, ZHANG Xue-yi, XIE Ya-zhou
    China Journal of Highway and Transport. 2012, 25(2): 67-71.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study longitudinal stiffness of middle pylon in the multi-span bridge, the main cable was treated as springs in considering its constraint to the tower. Displacement model was assumed and principle of virtual work was applied to deduce the analytic expression. And a finite element model was established and the comparison with the former one was made to verify its effectiveness. The research result indicates that the cable spring stiffness is related only to rise-span ratio and unit length weight of the bridge. There is a liner relation between cable spring stiffness and unit length weight. When rise-span ratio decreases, the main cable spring stiffness increases rapidly. Accordingly, the formula from it can be of high precision. The formula offer theoretical basis when proper parameters for multi-span suspension bridge in preliminary design stage are selected.
  • Longitudinal Dynamic Response to the Pile Embedded in Layered Soil Based on Fictitious Soil Pile Model
    WU Wen-bing, WANG Kui-hua, YANG Dong-ying, MA Shao-jun, MA Bo-ning
    China Journal of Highway and Transport. 2012, 25(2): 72-80.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on fictitious soil pile model, the longitudinal dynamic response to the pile under axial dynamic loading in layered general Voigt foundation was presented. The finite soil layers under the pile were modeled as fictitious soil pile in the range of cross-section area with the pile and the surrounding layered soils which were described with general Voigt model. By means of Laplace transform, the analytical solutions were obtained for the vertical dynamic response in the frequency domain and the relevant semi-analytical solutions in the time domain at condition of transient half cycle sine wave shaped on the pile top. Subsequently, the influence of parameters of pile end soil on the dynamic response at the pile top was investigated through parametric study method. Fictitious soil pile model and other pile end soil supporting model were compared. Theoretical result and field measurement curves of pile were fitted and compared. It has verified rationality of fictitious soil pile.
  • Bending Behavior and Ductility Test of High Performance Steel Beam Based on Hybrid Design
    WANG Chun-sheng, DUAN Lan, WANG Ji-ming, ZHENG Li
    China Journal of Highway and Transport. 2012, 25(2): 81-89.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the concept of hybrid design, 6 I-beams were designed and fabricated by high performance steel HPS 485W for flanges and steel Q235 for webs. In the bending test, these simple supported welding beams were loaded at mid-span. After the test, flexural capacity, deformation characteristics and the ultimate failure mode were analyzed during the whole experimental process. Test results show that web bucking strength and the rigidity of lateral bracing significantly affect the ultimate capacity, ductility and failure mode of tested beams.Flexural capacity is mainly contributed by flanges, and ductility is primarily affected by web. The descending stage of the bending capacity is controlled by the web bucking strength. It can be concluded that HPS beam with compact section has good plastic bending behavior and good ductility under effective lateral bracing system. Comparison between test result and theoretical calculation shows good coincidence between theoretical plastic moment and bending process in the test.
  • Method of Set Pair Analysis for Collapse Risk During Construction of Mountain Tunnel
    CAO Wen-gui, ZHAI You-cheng, WANG Jiang-ying, ZHANG Yong-jie
    China Journal of Highway and Transport. 2012, 25(2): 90-99.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve traditional analysis method of collapse risk of tunnels, based on a comprehensive analysis of the risk factors of tunnel collapse, firstly, the authors identified the main influence factors and formulated a two-stage synthetic assessment model of collapse risk of mountain tunnel. Secondly, according to the features of coexistence between determinacy information and uncertainty information on evaluation indexes, they introduced set pair analysis theory to establish connection degree evaluation matrixes, which could comprehensively describe the relationship between evaluation indexes and risk ranks from three aspects of identity,difference and antagonism. Thirdly, considering the uncertainties of the importance degree of evaluation index, limitation of experts' recognition and difference of experts' evaluation result reliability, they formulated and calculated its weights based on the method of uncertain analytic hierarchy process of group decision. Finally, they developed set pair analysis method of collapse risk during construction of mountain tunnel. Analysis and calculation of the practical engineering show that the established set pair analysis method of collapse risk during construction of mountain tunnel is feasible and reasonable.
  • Bi-level Optimization Model of Highway Network in Economic CircleBased on Differential Evolution Algorithm
    HU Qi-zhou, WU Juan, YUAN Chang-wei
    China Journal of Highway and Transport. 2012, 25(2): 100-105.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    On the basis of defining the connotation of the economic circle, this paper studies the optimization for highway network in the economic circle with the help of differential evolution algorithm. With the objective of optimization as its study of highway network in the economic circle and basis as its optimization principles and significance, the authors took traffic efficiency transportation cost, energy consumption, environmental protection and people's movement time as their functions for optimization goal, set up a bi-level model for highway network optimization in the economic circle and finally calculated them with differential evolution algorithm. The bi-level optimization model of highway network in economic circle fully utilizes the initial points of highways and refines them so that the traffic efficiency can be improved, and accordingly, highway network in the economic circle can also be optimized. Compared with the traditional model, the present one can go better with the traffic system in the economic circle and economic characteristics, and its conclusion can meet the practical needs of the situation in the economic circle. The results show that the optimization model cannot only meet the traffic needs in the economic circle, but also protect the environment and promote the sustainable development of the traffic system in the economic circle.
  • Selected Model and Sensitivity Analysis of Aggressive Driving Behavior
    FENG Zhong-xiang, LIU Jing, LI Yang-yang, ZHANG Wei-hua
    China Journal of Highway and Transport. 2012, 25(2): 106-112.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking 160 drivers as the research object, the influence factors of their aggressive driving behavior were analyzed through the theory of behavior and modeling method of disaggregate discrete choice. In the research, the authors determined variables for the influence factors of aggressive driving behavior choice and the ways to obtain their values, and developed a multinomial Logit (MNL) model. The influence degree and process to aggressive driving behavior were analyzed by elasticity theory. Another 58 drivers behavior data were selected to testify the model's validity. The result shows that the personality of the drivers and violation of other vehicle are the crucial factors to aggressive driving behavior, with the relative error of 10% between judgment data of scale and computational values by MNL, therefore the model accuracy can meet the actual requirements.
  • Budget-excess User Equilibrium Model Under Uncertain Supply and Uncertain Demand
    LU Biao, PU Yun, LIU Hai-xu
    China Journal of Highway and Transport. 2012, 25(2): 113-120.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to reflect travelers' risk aversive route choice behaviors in a more accurate and complete manner in a stochastic road network, a traffic assignment model that simultaneously considers reliability and unreliability of supply and demand was proposed, which was also named as budget-excess user equilibrium model. Analytical expression of budget-excess travel time in the case of traffic capacity followed Gamma distribution and link capacity followed uniform distribution was derived on the basis of it, the equilibrium model formulated as an equivalent variational inequality problem was founded. A small test network was provided to compare the properties of user equilibrium model, reliability-based user equilibrium model and budget-excess user equilibrium model. The results show that the proposed model is valid and feasible, whose equilibrium flow pattern is different from user equilibrium model and reliability-based user equilibrium model. With the increase in the demand level, reliability level and degradation degree of link capacity, the budget-excess travel time will accordingly become greater.
  • Research on Dynamic Model of Within-day Travel Mode Choice of Residents
    WAN Xia, WANG Wei, CHEN Jun
    China Journal of Highway and Transport. 2012, 25(2): 121-126.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve the current travel mode choice model and increase prediction model accuracy of travel mode, authors built a dynamic model of within-day travel mode choice. The mechanism of travel mode choice of residents was analyzed firstly. Then, the dynamic effect factors of travel mode choice were decided. Finally, thedynamic model of travel mode choice was built based on the MNL model. The effect of previous travel mode choice decision on current travel mode choice and the effect of main tour travel choice decision on sub-tour travel mode choice were considered as the dynamic effect factors in new model. The data of Huaibei city, Anhui Province were taken as example in this paper. The results show that the new model is much better and has a higher prediction accuracy than MNL model on the basis of single travel utility, and the meanings of the effect factors agree well with the truth of China. The mode choice dynamics model can be used for traffic planning and transportation policy making.
  • Minor Lane Capacity Simulation Method of Traffic Flow Under Major Stream with M3 Distributed Headway
    WANG Zhi-mei, LIN Bo-liang, YANG Fu-she
    China Journal of Highway and Transport. 2012, 25(2): 127-133.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to find whether the emulation value of minor lane capacity obtained by traffic and time control methods is closer to the theoretical value, the authors, on the assumption that the headway obeys M3 distribution and on the basis that gap acceptance theory is the basic theory, constructed two simulation models for the minor lane capacity on the ring intersection with the above two conditions. The simulation process was performed on VC++ 6.0 platform. The simulation results of minor lane capacity, accumulated time, and traffic flows of major lane were calculated, and then they were used for the comparison with theoretical data. The comparison results indicate that the relative error between theoretical time and the simulation time incurred by traffic control simulation method is less than that of time control simulation method. The simulation minor lane capacity gained by traffic control simulation method is much closer to the theoretical value than that of time control simulation method. This means that the effect of traffic control simulation method is better than time control simulation method.
  • Evaluation for Comprehensive Performances of Oil Pump Used in Vehicle Engine
    WU Wei-wei, MA Fu-yin
    China Journal of Highway and Transport. 2012, 25(2): 134-141.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve the research and design level of the oil pump used in vehicle engine lubrication system, the authors discussed its key performance indicators, and analyzed the characteristics and development trend of various oil pumps. The architecture and functions of oil pump test bench, and the typical experimental results were discussed in combination with the authors' recent work in production practice and experimental studies. On the basis of the research achievements found in literatures, the affecting factors of important performance indicators, such as displacement, volume efficiency, pressure fluctuation and the relationship among them were thoroughly studied. The oil pump vibration, noise test and analysis methods were demonstrated through a practical measurement case. The results show that the fixed-displacement oil pump cannot meet the requirements of energy saving and emission reduction. Therefore, further research and development for variable displacement pumps must be carried out. Numerical simulation based on the full cavitation model is an effective way to study the cavitation existing in the oil pump. The vibration and noise performance of the oil pump is affected by the impacts of both the pressure fluctuation and mechanical meshing, which should be taken into account in an integrated manner.
  • Study of Anti-wear Properties of Nano Ceramic Additives in Biodegradable Basic Oil
    LI Xian-min
    China Journal of Highway and Transport. 2012, 25(2): 142-146.
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    The rape seed oil with high biological degradation and comprehensive performance oil was used as basic oil. As engines need high friction performance and internal combustion, nano ceramics with extreme pressure and anti-wear performance was used as additives. With MS-800 type four-ball wear testing machine, the extreme pressure properties, anti-wear properties and friction coefficient were studied. The influence of different ratios of additives on the properties was analyzed, and the current performance and the existing performance were compared. Besides, with uniform design arrangements for test ,the complexity of nano ceramics additive and other additives was analyzed by regression with the SPSS software. The results show that with nano ceramic additives friction performance can be significantly improved and adding proper proportion can meet the requirements of the lubricating oil. When the amount of nano ceramics additive is 1.5%, the corresponding maximal non-seizer load PB is 646.6 N at most, and the wear scar diameter is 0.59 mm at least, the friction coefficient can be reduced by 27% at most; the complexity of nano ceramic additive and other additives, and the interaction between them can improve extreme pressure and anti-wear role of rape seed oil.
  • Dynamic Model and Braking Performance Simulation of Multi-axle Wheeled Engineering Machine
    GAO Jiu-hao, CHEN Guo-bing, HE Shao-hua, PAN Sheng-han
    China Journal of Highway and Transport. 2012, 25(2): 147-152.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to predict the braking performance of multi-axle wheeled engineering machine and provide reference for the brake system design, a four-axle wheeled engineering machine was set as the object, simulation study on braking performance of the machine was carried out after considering the influence of the adhesion coefficient, the location of the machine's mass center and the axle-loads shift. Based on the relationship between relative coordinates for wheels and absolute coordinates for whole machine, and the hypothesis of small compression deformation of the suspensions and tyres that is linear, dynamic model for the machine was proposed under its braking stability limit state. Brake distance influenced by different adhesion coefficients, the relative location of the mass center and the braking velocity were analyzed with MATLAB/Simulink. The simulation results and the experiment results were compared. The results show that the simulation results coincide with experiment results. The brake distance decreases with the increase in adhesion coefficient and in the longitudinal location of the mass center relative to the I axle center, while the brake distance increases with the increase in the height of the mass center and in the brake velocity. And Ⅰ axle-load and Ⅳ axle-load vary sharply during the process of braking.
  • Variable Displacement Control in Direction Changing Process of Concrete Pumping
    SHI Zhong-qiu, WANG An-lin, HU Yu-qin, JIANG Tao, ZHANG Qi
    China Journal of Highway and Transport. 2012, 25(2): 153-158.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the hydraulic impact problem in the main pump export, which caused by abrupt changing load and piston striking the cylinder bottom in direction changing process, the variable displacement control method in direction changing process of concrete pumping was raised. Under periodically abrupt changing load conditions, the authors comprehensively considered the pumping cylinder structure parameters and the displacement control time parameters based on the system's open-loop characteristic, took the shortest pumping time as the evaluation standard with the requirement of piston not striking the bottom of cylinder, and finally established a optimal model of concrete pumping direction changing process. The authors in the research took one type of concrete pump as an example, optimized the pumping cylinder structure parameters and the displacement control time parameters and then carried out simulation and experimental analysis for pumping both water and concrete. Results show that the hydraulic impact in the main pump export declines about 67% and the phenomenon of piston striking the cylinder doesn't happen after taking the variable displacement control method in direction changing process. This method provides a new approach for solving the design problems in concrete pumping open-loop control system under periodically abrupt changing load conditions.
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