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10 September 2018, Volume 37 Issue 09 Previous Issue    Next Issue
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Bridge & Tunnel Engineering
Highway & Railway Engineering
Port & Waterway · Hydraulic & Hydroelectric · Resources & Environment
Traffic & Transportation Engineering
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Bridge & Tunnel Engineering

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Time-Dependent Reliability Analysis of Bridges Based on Decoupled Extreme Load Effects and No-Prior Distribution Information LIU Yuefei1, 2, XIAO Qingkai1, 2, QU Guang1, 2, FAN Xueping1, 2 2018, 37(09): 1-6.  DOI: 10.3969/j.issn.1674-0696.2018.09.01 Abstract ( )   PDF (456KB) ( )   Bridge health monitoring system has produced a huge amount of data in long-term service periods, and how to reasonably deal with these data to predict the structural reliability is a key issue in the field of structural health monitoring (SHM). Considering the coupling and randomness of SHM extreme stress data, firstly, the coupled extreme stress signal was decoupled with single moving average method. Then, considering the distribution characteristics of decoupled data, Bayesian dynamic linear models (BDLM) with unknown variance of observation error were established to predict the decoupled extreme stress. Finally, the time-dependent reliability of bridge members was analyzed with first-order second moment (FOSM) reliability method. The research results will provide the theoretical basis for structural reliability prediction. References | Related Articles | Metrics

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Influence of Contact Surface on Dynamic Response of Bridge Pier Collided by Barge ZOU Yisong1, LIU Lei1, WANG Yinhui2, LUO Zheng2 2018, 37(09): 7-15.  DOI: 10.3969/j.issn.1674-0696.2018.09.02 Abstract ( )   PDF (1578KB) ( )   The form of impact contact surface has influence on the dynamic response of barge-bridge pier collision. Based on the FEM, the impact force and crush depth rule caused by barge-pier collision with plane contact surface and arc contact surface were researched. Furthermore, the mechanical mechanism of the difference of collision response was discussed, and dynamic responses of pier structures in different contact conditions were analyzed. Finally, the equivalent impact force available for pier design was proposed according to the equivalent principle of maximum dynamic response of pier under barge impact. The results show that the process of barge-bridge pier collision observably presents two stages: instantaneous elastic impact stage and later inelastic impact stage. The size and shape of the impact contact surface have significant influence on the elastic and inelastic collision responses of the pier collided by barge. The maximum impact force may not be taken as the basis for pier design directly, but the equivalent impact force can serve as a reference for design of pier. References | Related Articles | Metrics

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Precast Concrete Decks Production Technology of Prefabricated Steel Truss-Concrete Composite Continuous Rigid Frame Bridge XIANG Yanmao1, ZENG Dezi1, GAO Yanmei2, 3, SHAO Shuai2 2018, 37(09): 16-22.  DOI: 10.3969/j.issn.1674-0696.2018.09.03 Abstract ( )   PDF (2896KB) ( )   In order to make the bottom smoothness of the precast bridge decks meet the welding precision requirements of the pre-burying stud shear connector, and make the board splicing precision of precast bridge decks meet the design requirements, the precision control study was carried out for the bottom smoothness of the precast bridge decks and the manufacturing process of the joints between decks. It is proposed that the adjacent bridge board can be continuously standardized, and the inter-board joints can be adapted to meet the design and construction precision requirements. Strictly controlling pre-burying precision of assembled stud shear connector and using rigid formwork can ensure the bottom surface smoothness, which meets the joint requirements of weld seams between the steel vertical plates of PCSS shear connector and the top surface of the steel truss. The engineering practice indicates that the proposed method is simple and feasible, which can meet the accuracy requirements and is available for similar bridges to reference. References | Related Articles | Metrics

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Force and Deformation of EPBS Passing alongside Viaduct Pier at Close Distance BU Yafang1, SUN Lin1, LIU Liu1, LI Lei2 2018, 37(09): 23-27.  DOI: 10.3969/j.issn.1674-0696.2018.09.04 Abstract ( )   PDF (722KB) ( )   Most of urban subway tunnel excavations often pass underneath and alongside buildings or structures. In order to ensure the smooth excavation of tunnels, it is necessary to study the force and deformation of the existing structures. Based on the shield construction passing alongside a viaduct in a section of Xian Metro Line 4, the force and deformation caused by the shield passing alongside the viaduct pier was analyzed by means of numerical simulation and on-site monitoring; and the settlement value calculated by numerical calculation was compared with the actual monitoring value. The results show that: the size of earth pressure has great influence on the surface subsidence for the shield construction in the sand layer environment, and the pier has certain restraining effect on the surface settlement. The settlement of the existing structure can be effectively reduced by proper placement of pile foundation in the shield construction. The above conclusions can provide reference for the risk sources of similar shield passing alongside. References | Related Articles | Metrics

Highway & Railway Engineering

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Key Technology of Large Size Precast Concrete Slab Pavement SONG Wali1, CAO Mingyu1, PANG Xu1, REN Yanxia2 2018, 37(09): 28-33.  DOI: 10.3969/j.issn.1674-0696.2018.09.05 Abstract ( )   PDF (744KB) ( )   Considering various causes of cement concrete pavement diseases, large size precast concrete slab pavement structure with graded gravel as base course was put forward. By means of finite element analysis, the hosting of precast concrete slab was simulated, and the plane dimension of the precast concrete slab was determined. Mechanical analysis model was established to calculate the strength of pavement structure, and the influence of plane dimension, thickness of precast slab and thickness of base course on stress of pavement structure was analyzed. In order to fully understand the mechanical properties of pavement structures, permanent deformation of base course and overlap between different plates were studied. Automatic construction equipment for concrete slab was developed, and the joint structures between slabs were rationally designed to ensure quality of construction. Aiming at the characteristics and requirements of rural roads, the typical structure of precast concrete slab pavement for rural road was proposed. The typical structure was 15 cm flexible base (graded broken stone)+1 cm seal coat(asphalt)+5 cm sand cushion +22 cm surface course(large size precast concrete slab). References | Related Articles | Metrics

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Automatic Crack Detection Algorithm from 3D Pavement Images Based on Shape Analysis at Pixel-Subpixel Level PENG Bo1, HUANG Darong1, GUO Li2, CAI Xiaoyu1, LI Shaobo1 2018, 37(09): 34-42.  DOI: 10.3969/j.issn.1674-0696.2018.09.06 Abstract ( )   PDF (2076KB) ( )   In order to detect pavement crack accurately and effectively as well as provide data basis for pavement performance evaluation, pavement maintenance and management, pavement structure and material design, an automatic pavement crack detection algorithm was proposed based on shape analysis at pixel-subpixel level aiming at 1mm/pixel 3D pavement images. Firstly, candidate crack targets were detected and fused by Canny algorithm and Region Growing method respectively, thus the fused segmentation image was obtained. Secondly, image skeletons at pixel level and subpixel level were extracted and reconstructed. Finally, image skeletons at pixel level and subpixel level were fused, and cracks targets were extracted by comprehensively applying morphological operators and shape features of connected components like contour length, roundness, flat-ratio, et al. Tests of the proposed algorithm and other 5 existed algorithms were conducted based on 150 3D pavement images (992 pixels × 992 pixels). The results show that the proposed algorithm achieves relatively high precision (averaging 90.45%) and recall rate (averaging 96.49%), and average F-measure values rank as follow: the proposed algorithm (90.72%), the parallel seed growing method (39.65%), GAVILN method (33.46%), the anisotropy method (30.32%), Canny detection (25.85%), OTSU segmentation (5.85%). Algorithm applicability analysis indicates that the proposed algorithm is suitable for recognizing tiny or thin cracks,the parallel seed growing method, GAVILN method and anisotropy method have advantages in detecting wide and obvious cracks, and Canny and OTSU can be commonly utilized as an image processing unit of crack detection algorithms. References | Related Articles | Metrics

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Evaluation Index of Foamed Asphalt Based on Non-contact Method HUANG Weirong1, REN Haisheng2 2018, 37(09): 43-47.  DOI: 10.3969/j.issn.1674-0696.2018.09.07 Abstract ( )   PDF (430KB) ( )   In view of the fact that the existing evaluation indexes of foamed asphalt, that is expansion rate and half-life,had shortcoming in evaluating the foaming effect of foamed warm mix asphalt, three evaluation indexes such as foam diameter, size distribution and defoaming rate were proposed to evaluate the foaming effect of foamed warm mix asphalt, which was according to the result of non-contact test method based on laser range finder, digital camera and other equipment. The test results show that the water consumption has greater influence on foam diameter than the asphalt temperature, which verifies the water consumption has greater influence on asphalt foaming effect than asphalt temperature.The 90 s foam size distribution is the most concentrated, which is consistent with the foam stability mechanism in asphalt foaming.The k value of defoaming rate increases with the increase of water consumption,which confirms that the half-life decreases with the increase of water consumption. In addition,the change of defoaming rate shows that the foamed asphalt can improve the workability of asphalt mixture during mixing, transportation, paving and rolling stages.So non-contact test method combining with the proposed three indexes can accurately characterize the whole process of asphalt foaming and better evaluate the foaming effect, which is helpful to find the best mixing time points, foaming temperature, water consumption and etc. according to actual construction requirements of foamed warm mix asphalt. References | Related Articles | Metrics

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Impact of Water Content and Sand Content on Performance of Improved Gravel Soil with Dimeric Materials PEI Xiangjun, LUO Yangchujun, YANG Qingwen 2018, 37(09): 48-52.  DOI: 10.3969/j.issn.1674-0696.2018.09.08 Abstract ( )   PDF (896KB) ( )   The gravel soil along Mianyang-Jiuzaigou express way was selected to study the impact of water content and sand content on the performance of dimeric material modified gravel soil. The experiment results show that dimeric material has significant impact on the improvement of cohesion and water resistance of gravel soil; the water content has obvious effect on cohesion force of the reinforced soil, and when the water content is the limit value of the gravel soil, the cohesive force reaches the maximum value, which is 135 times as large as that of the natural gravel soil; but the water content is insensitive to the internal friction angle of the reinforced soil. With the increase of sand content, the shear strength parameters of the reinforced soil show a tendency of increase first and then decrease. When the sand content is 5%, the internal friction angle of soil samples increases to be the maximum. References | Related Articles | Metrics

Port & Waterway · Hydraulic & Hydroelectric · Resources & Environment

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Advances on Flow-Deformation Coupling Theoretic Research of Soils LU Peiyi, HAN Yafei, WANG Chenghua 2018, 37(09): 53-59.  DOI: 10.3969/j.issn.1674-0696.2018.09.09 Abstract ( )   PDF (598KB) ( )   Traditional seepage calculation and deformation calculation are carried out separately. The traditional method is simple, but it is not suitable for engineering practice with low accuracy. After a lot of scholars research on seepage field and stress field coupling at home and abroad, the coupling theories from different angles were obtained. In order to express the essence of all theories and reflect the difference between theories, the flow-deformation coupling theory was classified and evaluated from 4 aspects: computational domain coupling, basic unknown coupling, parameter coupling and constitutive relation coupling. The conclusion has drawn that the computational domain coupling is a simple computational method but with low precision; the basic unknown coupling has a perfect theory system; the parameter coupling is only established for a certain type of soil, and lacks universality; the constitutive relation coupling should be further studied in cohesive soil. References | Related Articles | Metrics

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Pollutant Emission Monitoring and Pollution Characteristics of Motor Vehicles in Freight Stations CHEN Yanyan1,QIN Weiling1, LI Xiaoyi2,WU Kehan1, CHEN Ning1, SONG Chengcheng1 2018, 37(09): 60-65.  DOI: 10.3969/j.issn.1674-0696.2018.09.10 Abstract ( )   PDF (1044KB) ( )   Freight station is the distribution field of a large number of trucks, which belongs to high emission pollution area in transportation infrastructures. Through the real-time monitoring of vehicle emission from freight stations, the environmental basic data of freight hub were obtained. The emission characteristics of three functional areas such as cargo handling area, internal road intersection and entrances and exits were studied. It is found that the concentration of NOx and PM is positively correlated with the traffic flow; the proportion of large and medium-sized trucks in traffic flow has a significant effect on NOx and PM emissions; the increasing pollutant discharge during forklift operation is an important reason for heavy pollution in loading and unloading area of the station. References | Related Articles | Metrics

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Suitability Evaluation of Rural Construction Land Based on the Concept of “Inverse Planning” WANG Guilin1,2, JIANG Wei2, WANG Peng3, HE Jian3 2018, 37(09): 66-72.  DOI: 10.3969/j.issn.1674-0696.2018.09.11 Abstract ( )   PDF (731KB) ( )   With the acceleration of the urbanization process in China, the land resources in rural areas need to be developed and utilized urgently; more and more attention has been paid to the suitability evaluation of construction land in rural areas based on the concept of ecological protection. In order to ensure the regional ecological integrity in the process of evaluating the land, the concept of “inverse planning”was introduced, that is, the method of prior planning for the construction of ecological safety forbidden zones, which planed the land from the control of regional ecological infrastructures.In the case study of Yihe town in Fuling District of Chongqing, the construction land suitability evaluation method was constructed by combining the concept of “inverse planning”and the comprehensive index evaluation model.The results show that compared with the traditional evaluation method,low safety level areas increase and middle and high safety level areas decrease in the proposed evaluation results, which can better guarantee the regional ecological integrity. It can also be applied to different land demand under different economic conditions in mountainous rural areas, which has important reference significance for mountain rural area planning. References | Related Articles | Metrics

Traffic & Transportation Engineering

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Self-adaptive Control of Isolated Intersection Based on Short-Term Traffic Flow Prediction XU Jianmin1, 2, LI Kuilin1, ZHAI Chunjie1, XIAO Yahui2 2018, 37(09): 73-78.  DOI: 10.3969/j.issn.1674-0696.2018.09.12 Abstract ( )   PDF (561KB) ( )   Focused on the unsaturation of traffic flow at isolated urban intersection, an isolated intersection self-adaptive control strategy based on K-nearest neighbor short-term traffic flow prediction method was proposed to make the isolated intersection control strategy applicable for dynamically variable traffic flow. Firstly, the traffic flow of the future 5min was predicted according to the historical traffic flow data at the intersection, and the signal cycle was calculated. Then, a self-adaptive control model of the isolated intersection with parameters of maximum cycle, phase sequence and maximum phase time was established, which could adjust automatically the parameters value of phase sequence, the maximum phase time and green light delay time according to the real-time traffic state information. Finally, an isolated intersection in Nansha District of Guangzhou was simulated by software VISSIM 4.3, and the average vehicle delay time was taken as the evaluation index, which was compared with the fixed timing and the piecewise timing control methods. The simulation results show that compared with the fixed timing and the piecewise timing control method, the total delay time of the vehicle obtained by the proposed method is reduced by 35% and 15% respectively, which effectively improves the vehicle traffic efficiency at the intersection. References | Related Articles | Metrics

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Application of Improved Hybrid Genetic Algorithm in the Modeling and Optimization of Multi-trip Vehicle Routing Problem with Time Windows SONG Qiang 2018, 37(09): 79-86.  DOI: 10.3969/j.issn.1674-0696.2018.09.13 Abstract ( )   PDF (560KB) ( )   The multi-trip vehicle routing problem with time windows and delivery time was discussed under the background of urban logistics. In the urban logistics context, trucks delivered merchandise to depots located in the outskirts of the city, and the goods were delivered to the warehouse continuously and the final allocation was made in the working days. The concept of delivery time associated with merchandise was introduced, and an improved hybrid genetic algorithm based on the new auxiliary segmentation process was proposed to solve this problem. Under the restriction of the time window and the delivery time, combined with a set of examples, the simulation experiments show that the proposed algorithm has high efficiency by comparing with the multi-trip optimization algorithms in the related literature. References | Related Articles | Metrics

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Multi-objective Shortest Path Algorithm Based on Road Section Assignment Method FENG Shumin1, WANG Xiankai1, SUN Xianglong2 2018, 37(09): 87-92.  DOI: 10.3969/j.issn.1674-0696.2018.09.14 Abstract ( )   PDF (449KB) ( )   Considering the influence of the number and distance of each route between the origin and the destination on route selection, a calculation method of road section assignment was put forward. Based on the linear weighting method, a new evaluation function was constructed by using the assignment of road sections. It was proved that the optimal solution obtained by this method was the non-inferior solution of the multi-objective shortest path problem. Combined with the K-shortest path algorithm, the computational procedure of road section assignment method to solve the multi-objective shortest path problem was given out. Taking the transport network of Pingxiang City in Jiangxi Province as an example, the conventional linear weighting method, the geometric weighting method and the road assignment method were compared. The results show that the road section assignment method can obtain the local optimal solution, and it can estimate the importance of each target accurately when the weight changes. References | Related Articles | Metrics

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Optimal Design of Urban Bus Lanes Considering Negative Impact Minimization SHI Qin1, YU Zhongwei1, CHEN Yikai1, WU Peng2, XIA Bangjin3 2018, 37(09): 93-100.  DOI: 10.3969/j.issn.1674-0696.2018.09.15 Abstract ( )   PDF (503KB) ( )   Aiming at the problem of long running time of some bus routes due to traffic congestion in a public transit network, a bus lane optimization model based on negative impact was established to improve the efficiency of bus from the point of view of system optimization. For bus lines with long running time often caused by congestion, the percentage of optimization (percentage of running-time reduction) was determined according to actual demand firstly. Under the premise of ensuring the optimized line to reach the optimization standard, the negative impact, which measured by the increased travel time for social vehicles after setting the bus lane, was minimized. The cut-and-solve algorithm was proposed to solve the model accurately. Finally, in the case study of bus network in Hefei, the effectiveness of the proposed model and its solve algorithm was verified based on a large number of data surveys. The calculation results show that when the negative effect reaches the minimum 0.25 × 106 s, the running time of the optimized line is reduced by 20%. At the same time, the total running time of the road network is reduced by 0.36% and the total running time of the bus is reduced by 22.97%. Therefore, the proposed bus lane setting method ensures the efficiency of bus while minimizing the impact on social vehicles. References | Related Articles | Metrics

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Satisfaction Evaluation of Public Transit Service Based on Entropy Weight Method and Cloud Model GUO Xiaofan1, LI Linbo2, WANG Yanli2, ZHAO Shanshan3 2018, 37(09): 101-106.  DOI: 10.3969/j.issn.1674-0696.2018.09.16 Abstract ( )   PDF (555KB) ( )   In order to evaluate the satisfaction degree of public transit service, an evaluation methodology combining entropy weight method with cloud model was proposed. Based on the variability of data, evaluation index was weighted objectively by using entropy weight method. The index data was converted to the corresponding cloud parameters by backward cloud generator on the basis of cloud model theory, and the evaluation cloud was built by index approximate method. Evaluation results were showed as normal cloud diagram. The public transit service satisfaction degree in Jiading District of Shanghai was evaluated comprehensively by using above method. The evaluation result indicates that the satisfaction degree of public transit service in Jiading District is moderate and presenting a trend of turning better. Therefore, the evaluation result can intuitively and accurately reflect passengers satisfaction degree of public transport services. References | Related Articles | Metrics

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Traffic Volume Prediction Method of Railway Passenger Dedicated Line at Initial Operation Stage ZHONG Yiying1, CHEN Jian1, 2, SHAO Yiming1, 2 2018, 37(09): 107-112.  DOI: 10.3969/j.issn.1674-0696.2018.09.17 Abstract ( )   PDF (401KB) ( )   In order to solve the problem of passenger flow instability in the early stage of railway passenger dedicated line, taking full account of the potential demand under transport restrictions, a multivariate Logit model was constructed to forecast the traffic flow in the channel based on the economy and transport impedance of transportation modes. Meanwhile, the induced passenger volume was forecasted through the comparison of passenger service promotion rate before and after the operation of passenger dedicated line. Then taking the newly built Chengdu-Mianyang-Leshan passenger dedicated line as an example, the total passenger traffic volume of the channel in 2017 and 2020 was obtained by forecasting the trend passenger volume, the transfer passenger volume and the induced passenger volume respectively at initial operation stage. The above study provides a new idea for forecasting the system of railway passenger dedicated line. References | Related Articles | Metrics

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Visualization Analysis for Research Hotspots of Rail Transit in China ZHANG Fugui1, CHEN Weiwei2, ZHAO Xiaobo1 2018, 37(09): 113-121.  DOI: 10.3969/j.issn.1674-0696.2018.09.18 Abstract ( )   PDF (954KB) ( )   In order to fully understand the current situation and the research focus in the field of rail transit, the social network analysis method was used to study the scientific research papers in the field of rail transit. The network model of high frequency keyword was constructed, and the network density, connection strength and network location of the model were visualized to reveal research hotspots in this field. Meanwhile, the mainstream research journals, major subjects, representative institutions and their research characteristics in this field were dug out. The result shows that the institutions with high volume of documents in the field of rail transit are important research forces in the region, which have different research characteristics. This research hotspot analysis from the perspective of bibliometric provides an important method or paradigm for mining research hotspots in a certain field. References | Related Articles | Metrics

Vehicle &Electromechanical Engineering

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Effect of Walking Wheel Failure on Dynamics Performance of Straddle-Type Monorail Vehicle DU Zixue1, TANG Fei1, HE Qinhong1, LV Zhiming2 2018, 37(09): 122-127.  DOI: 10.3969/j.issn.1674-0696.2018.09.19 Abstract ( )   PDF (570KB) ( )   According to the structural characteristics of straddle-type monorail vehicle, the monorail vehicle dynamics model of walking wheel failure was established by the multi-body dynamics software (ADAMS). On this basis, the influence of the walking wheel failure on the dynamic performance of the monorail vehicle under different working conditions was analyzed. The results show that: the safe running speed limit of the curve R100 m is 35km/h and 30km/h respectively when the walking wheels fail in the idle (AW0)and over-loading (AW3)state; the trend of walking wheel failure on the same side of the curve is basically the same for the safety of vehicle operation; the effect of the failure of the inner walking wheel and the failure of the outer walking wheel on the safety performance of the vehicle has great difference; when the speed is large, the failure of the outer walking wheel of the bend has a greater impact on the safety performance of the vehicle. Compared with normal operation, when the walking wheels fail, the lateral stability increases by 0.2~1.1, the vertical stability increases by 0.2~1.2, and the vertical stability of the part has exceeded 3. The walking wheel failure has great influence on the running stability of the straddle monorail vehicle. When the walking wheel failure occurs, the running stability of the vehicle becomes worse and the vehicle should slow down and reach the neighboring site to evacuate passengers as soon as possible. References | Related Articles | Metrics

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Simulation Research on Braking Performance of High-Speed Train in Alpine Region CHEN Zheming1, LIANG Dandan1, ZHANG Junling2 2018, 37(09): 128-134.  DOI: 10.3969/j.issn.1674-0696.2018.09.20 Abstract ( )   PDF (618KB) ( )   The dynamic model of high-speed train was established by Simpack. The force of the train braking process in the alpine region was analyzed. The emergency braking and the maximum common deceleration curve of the 400 km/h high-speed train were designed and the adhesion checking was carried out. The results show that the designed deceleration curve can meet braking requirements of the 400 km/h high-speed train. The model of braking system was established by MATLAB/Simulink. Through the simulation and calculation, the emergency braking distance and the maximum common braking distance were obtained under the dry and snow conditions in alpine region. References | Related Articles | Metrics