Volume 43, Issue 3 (2023)
Specially Invited Article
Research progress on properties of fiber modified asphalt mixture
LIANG Bo, ZHANG Haitao, LIU Zheng, and LIAO Wei
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.001
As a kind of asphalt mixture additive and stabilizer, fiber can effectively improve the performance index of asphalt pavement and extend the service life of asphalt pavement. Based on the analysis of relevant literature in China and abroad, this paper summarized the action mechanism of fiber modified asphalt and asphalt mixture, the effect of fiber content on properties, and the characteristics of different types of fiber modified asphalt. Fiber can effectively improve the high temperature property, low temperature property, and fatigue property of asphalt mixture, especially the resistance to low temperature and fatigue cracking of asphalt mixture. The modification effect of fiber can be improved by choosing the appropriate fiber length and content and the surface structure of the modified fiber. Fiber composite modified asphalt can improve the performance of single modified asphalt and further enhance the comprehensive performance of asphalt mixture. Fiber modified asphalt mixture can comprehensively improve the overall performance of asphalt pavement and provide technical support for durable and long-life pavement. Finally, the influence of the fiber reinforcement mechanism on the properties of the asphalt mixture was analyzed, and future research direction was given.
Subgrade Engineering
Review of research progress of frame beam anchore d structure in slope supporting
ZHANG Junhui, ZHOU Qinwei, LI Feng, and ZHANG Shiping
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.002
This paper summarized the research status of frame beam anchored structures in slope supporting and reinforcement engineering in China and abroad. It analyzed the results of structural design, model test, and field construction. Through induction and analysis, it is found that the current design of frame beam anchored structure has certain limitations, and it is necessary to form a universal design theory and method. The model test of frame beam anchored structure in slope supporting is limited by the test equipment and conditions and fails to be carried out on a large scale. The key points and standards of the construction quality control of frame beam anchored structures are not clear enough, and there is a lack of perfect frame beam construction technology. It is necessary to carry out systematic research on construction safety risks from the perspectives of human, material, environment, and management. The combined application of frame beam anchored structure and prefabricated structure is worthy of further study.
Numerical analysis of structural characteristics of prefabricated ecological grid retaining walls
WANG Xinquan, ZHU Cong, HUANG Tianyuan, DIAO Hongguo, and PENG Xijian
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.003
The retaining wall is a common slope protection structure. In view of the current insufficient greening and high prefabricated retaining walls, prefabricated ecological grid retaining walls with high construction efficiency and greening features emerge. In order to explore the mechanical characteristics and influencing factors of prefabricated ecological grid retaining walls, Abaqus finite element software was used to discuss the mechanical characteristics of prefabricated ecological grid retaining wall columns and inclined shelves with different embankment heights and different fillings. The results show that different fill heights have different effects on the lateral displacement of the column, and the effect of fill height on the column can be ignored when the fill height is less than 1 m. The lateral displacement of the retaining wall decreases with the increase in cohesion and the decrease in internal friction angle. When the retaining wall is an embankment wall, the equivalent internal friction angle method is not suitable for calculating the force of the inclined shelf. The lateral displacement of the column is small and rotates around the bottom of the column. Due to the open structure of the inclined shelf, the stress distribution law of the inclined shelf is a U-shaped curve, which is different from the trend of the soil arch effect between piles which first increases and then decreases. When the anchor of a single column fails, the increase in lateral displacement of the column is small, and the resultant force point of the inclined shelf is offset.
Study on effectiveness evaluation method of expressway drainage system in rainy area
LUO Datian, LI Jiayi, and ZOU Jingrong
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.004
In order to comprehensively evaluate the effectiveness of expressway drainage systems in rainy areas and comprehensively analyze the factors affecting the effectiveness of drainage systems, this paper took the perfection of drainage system, stability of drainage facilities, and road traffic safety as the first-level evaluation index and six kinds of influencing factors such as the degree of integrity as the second-level index, and it put forward the evaluation criteria of the effectiveness of expressway drainage system in rainy areas. The fuzzy comprehensive evaluation method was used to determine the membership degree of expert scoring through the trapezoid membership function, and then the weight of evaluation indexes was determined by the analytic hierarchy process to establish an evaluation system. An expressway in Hunan Province was taken as an example to analyze and verify the results. The results show that the conclusions obtained by using the evaluation model are basically consistent with the qualitative field investigation, which has a certain reference value for the effectiveness evaluation of the expressway drainage system in rainy areas.
Macro and micro analysis of influence mechanism of anti⁃slide pile position on slope stability
LIU Ping, WANG Meijing, ZHANG Shaoqiang, ZHANG Yongsheng, WANG Denghua, and LI Dongdong
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.005
In order to study the influence mechanism of anti-slide pile position on the stability of the slope and optimize the supporting parameters of anti-slide piles reasonably, a three-dimensional continuous and discrete coupled numerical model of the slope was established based on the finite difference theory and discrete element theory of a highway cut slope in southwest China. The influence mechanism of anti-slide pile position on the stability of the cut slope was analyzed from macro and micro perspectives. The results show that the force chain of particles on the sliding surface is thin at the top and dense at the bottom, and the rotation state of particles has an obvious stratification phenomenon. The contact force chain and rotation state of particles in the discrete domain can represent the stable state of the slope body from the microscopic level. The position of the anti-slide pile affects the position and shape of the slide surface, and the maximum displacement of the slope decreases first and then increases when the pile moves from bottom to top. The bending moment curve of the anti-slide pile is approximately parabolic, and the maximum value is located at the top of the rock-socketed section of the anti-slide pile; the maximum value of shear occurs below the rock-socketed end of the pile.
Pavement Engineering
Experimental study on interface fatigue c haracteristics of asphalt p avement pothole patch under external factors
AI Changfa, SHAO Zhutao, HUANG Yangquan, and REN Dongya
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.006
After the asphalt pavement patch for potholes is put into use, the interface joints around it are prone to fatigue and durability problems under the action of external factors such as the natural environment and driving load effect. In order to analyze the fatigue characteristics of the repaired interface joints under the action of external factors, the four-point bending fatigue test and pull-out test, combined with the results of orthogonal analysis, were used to determine the best bonding scheme of the repaired interface. The influence of external factors such as temperature, frequency, and strain level on the fatigue life of interface joints was analyzed. Based on the Origin software platform, the fatigue life prediction model of repaired interface joints of asphalt pavement under the action of external factors was constructed. The results show that the fatigue life of the interface joints decreases with the increase in the strain level under the optimal repair interface, but the decreasing trend of fatigue life of the interface joints is different under different load frequencies and temperatures. A higher temperature indicates a lower fatigue life of interface joints, and with the increase in temperature, the fatigue life of interface joints decreases faster. Under the same repair measures, the fatigue life of interface joints is smaller when the vehicle is running at high speed and high frequency. The fatigue life prediction model of interface joints under the comprehensive action of external factors established in this paper has high accuracy and can be used to predict the life of interface joints in similar pavement repair projects.
Detailed structure of double ⁃layer porous asphalt pavement under three paving technologies
ZHANG Zhenshan, LIAO Gongyun, WANG Can, ZHANG Yi, CAI Yang, FANG Xin, and WU Wei
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.007
For three kinds of construction technologies of double-layer drainage pavement (traditional “hot + cold” paving technology, “hot + warm” paving technology, and “hot + hot” integrated molding technology), the discrete element method and laboratory test were used to make plate specimens and cylindrical specimens, respectively, and the interlayer morphology of double-layer drainage pavement under the three kinds of construction technologies was compared. Based on the virtual shear test and laboratory direct shear test, the effects of construction technologies and amount of adhesive oil on the interlayer shear strength of double-layer drainage pavement were analyzed. By means of visualization, the distribution law of void ratios in different layers was obtained. The results show that the interface between layers in the traditional paving technology tends to be horizontal, while the interface between layers in the other two paving technologies is staggered and squeezed. The shear strength of the interlayer interface of the double-layer drainage pavement based on the integrated molding technology is significantly higher than that of the two paving technologies. Under the three construction technologies, the void ratio of each layer basically conforms to the distribution law of smaller near the center of the specimen and larger outside the specimen. The “hot + warm” paving technology is a construction method worth exploring for the current double-layer drainage pavement.
Study on improvement of early skid resistance of SMA asphalt pavement based on spreading grit
JIANG Zhaowei, WEI Jincheng, LIU Hang, SUN Qiang, and LI Xia
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.008
The early skid resistance of SMA 13 pavement is poor. To address this issue, the existing research results were analyzed, and physical detection was conducted. It was found that the large structure pavement failed to provide good early skid resistance detection value. Based on the principle of spreading abrasive materials, two methods to improve the early skid resistance of SMA pavement were proposed. The particle size of abrasive material was determined to be 2.36–4.75 mm, and the spreading amount was 0.82 kg/m2, which verified the safety of the methods. The test results show that the two methods can slightly improve the skid resistance coefficient of the swing type, and the improvement rate of method 2 is higher. After the implementation of method 1, the dynamic friction coefficient and lateral force coefficient are increased by 10% and 13.2%, but the lateral force coefficient still cannot meet the requirements. In method 2, the dynamic friction coefficient and lateral force coefficient are increased by 73.2% and 77.8%. Both methods reduce the depth of the structure, but it remains above 0.8 mm. It is considered that a larger depth of the structure is unsatisfactory, and an upper limit should be set to ensure the initial skid resistance. The effects of the two methods on the long-term skid resistance of the pavement need to be studied.
Crack resistance of basalt fiber asphalt pavement under the coupling effect of low temperature⁃load in heavy freezing area
GUO Yinchuan, HAO Chenwei, GUO Han, FAN Li, SHEN Aiqin, and WANG Lusheng
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.009
In view of the cold working environment and road diseases of asphalt pavement in the heavy freezing area of Inner Mongolia, a control index of pavement structure based on crack resistance was proposed. The calculation models of the newly built basalt fiber asphalt pavement structure and the pavement after cracks were established by using Ansys finite element software. The mechanical parameters, thermophysical parameters, and other parameters of the basalt fiber asphalt pavement were determined through laboratory tests, and the crack resistance indexes under the coupling action of low temperature and load were calculated, respectively. The fatigue life of basalt fiber asphalt mixture was tested to verify the correctness of the finite element simulation results. The results show that under the coupling effect of low temperature and load, the crack resistance indexes of the newly built basalt fiber asphalt pavement at the crack point are improved. The influence of different load positions on different crack propagation periods of cracked basalt fiber asphalt pavement is different. The crack coefficient index KR of cracked basalt fiber asphalt pavement is smaller under the effects of low temperature-positive load KⅠ, low temperature-partial load KⅠ, and low temperature-partial load KⅡ. Under different temperatures and stress levels, the fatigue life of basalt fiber asphalt mixture is always significantly higher than that of ordinary asphalt mixture.
Bridge Engineering & Tunnel Engineering
Design and stress analysis of baqiutian jointless arch br idge in yunnan
CHEN Baochun, SUN Tongqing, HUANG Qingwei, HAN Yu, and SHI Zhi
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.010
The bridge without expansion joints, with the expansion device removed, can completely solve the maintenance problem of the expansion device and is sustainable. Its application is mainly in beam bridges and relatively few in arch bridges. In this paper, the Baqiutian Bridge in Yunnan Province was taken as an example, which is an upper bearing arch bridge. The arch path structure is directly connected with the two approach spans to form a continuous structure and extends to the guide plate (approach slab) behind the platform, thus eliminating the expansion joints of the whole bridge floor and making it an arch bridge without expansion joints. This paper described the main types of arch bridges without expansion joints, focused on the design of Baqiutian Bridge, and analyzed the effect of deck expansion amount of upper bearing arch and the removal of expansion joints on the structural force.
Optimization design of UHPC ⁃NC continuous box girder bridge based on response surface method
GUAN Weiyi and DUAN Luqi
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.011
In order to solve the two major problems of mid-span deflection and cracking in the late stage of the long-span bridge, a UHPC-NC hybrid beam design scheme was proposed, and some design parameters were optimized based on the response surface method. By optimizing the local parameters, namely the thickness of the roof, web, and bottom plates of the mid-span section, and the overall parameters, such as the UHPC replacement ratio, the number of beam curves, and the height of the mid-span beam, the optimal parameter combination was obtained as follows: roof thickness of 22 cm, web plate thickness of 25 cm, bottom plate thickness of 32 cm, UHPC replacement ratio of 0.63, curve times of 1.8, and height of the mid-span beam of 3.35 m. Then, the finite element model was established based on the optimal parameter combination and compared with the original design model. The results show that the top bending moment of each pier is reduced by more than 12%; the bending strain energy of the whole bridge is reduced by 34.7%; the stress of the upper and lower edges of each key section is generally reduced by 12%, and the maximum deflection is reduced by 23.3%.
Case study of steel wire corrosion in hoist cable of half ⁃through arch bridge
XU Hongsheng, JIANG Lei, and YAN Donghuang
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.012
In order to understand the causes and development rules of steel wire corrosion diseases inside the hoist cable of half⁃through and through arch bridges, this paper systematically studied the defects and loopholes of the protection system for the hoist cable of two half⁃through steel arch bridges by disintegrating the old hoist cables of Yuehai Bridge in Yinchuan and Xiangjiang Bridge in Heishipu Street in Changsha City. It probed into the distribution rules of corrosion diseases of steel wire inside the hoist cables. The main reasons leading to the difference in steel wire corrosion disease inside the old hoist cables of the two bridges were qualitatively analyzed, providing a reference for the corrosion protection of the hoist cable and the formulation of management and maintenance strategies for half⁃through and through arch bridges during operation.
Analysis and optimal adjustment of manufacturing errors of main girder of long ⁃span steel box cable ⁃stayed bridge
TU Guangya and ZHOU Zhizhe
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.013
In order to study the influence of the random manufacturing error of the main girder permitted by the research specification on the alignment of the finished long-span steel box cable-stayed bridge, guided by the adaptive stress-free configuration construction control theory, the Shishou Yangtze River Highway Bridge, a long-span twin-tower cable-stayed bridge, was studied. The influence and propagation characteristics of the random error effect of the main girder members on the main structure of the cable-stayed bridge were analyzed. The adverse effects of random manufacturing errors of the main girder on the structure of the cable-stayed bridge were studied. The results show that the alignment of the main girder during construction and completion will be changed due to the small geometric random error during the manufacture of the main girder. The random error of girder length has no obvious influence on the alignment of the finished bridge, while the random rotational angle error between adjacent beam segments has a relatively large influence on the alignment of the finished bridge. The alignment error of the finished bridge can be effectively reduced by optimizing the installation cable force when the alignment error caused by the random manufacturing error is too large.
Research on budget quota of highway bridge crack treatment
CHANG Ding and YU Licun
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.014
In view of the lack of a unified budget quota for concrete structure crack treatment, a large number of measured data and fuzzy analytic hierarchy process were used to calculate the consumption of budget quota through the amplitude difference coefficient of construction quota. According to the technical specifications of highway bridge reinforcement engineering, reasonable crack treatment methods and engineering contents were determined, and the quota of structure crack treatment was prepared by using the physical quantity. The quota cost was compared with actual engineering cases. The results show that the quota cost and the actual project cost are basically at the same level, which can accurately reflect the actual cost of crack treatment of highway bridge structures.
Design of super large cantilever wing ⁃box girder bridge
ZHONG Hao
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.015
In recent years, with the rapid development of urban bridge construction, the bridge inevitably needs to cross the existing railway and road in the construction project. This kind of bridge has the characteristics of a large span and limited pier space. At the same time, in order to meet the increasing traffic demand, the transverse width of the bridge is increasing, so the application of large cantilever wing-box girder structures is becoming more and more extensive. Based on the overspan railway bridge project of the northern section of the Wuhan Fourth Ring Line (Wuhu–Wujiashan), this paper introduced the design difficulties of super-large cantilever continuous beam bridges, analyzed the structural stress characteristics and stress states through theoretical calculation, and put forward solutions and measures from the perspective of structural design, providing a reference for the design of similar projects in the future.
Study on reasonable seismic system of long ⁃span concrete beam bridge in strong earthquake areas
YU Deen, HAN Shanjian, and SUN Pingkuan
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.016
In this paper, a three-dimensional finite element dynamic model of the Longtang Nandujiang Bridge in Hainan Province was established. Firstly, the selection of ground motion input and the establishment of the finite element model were introduced. Secondly, the influence of different design parameters (support radius) of the friction pendulum bearing on the seismic response of the bridge was discussed, and the optimal bearing parameters suitable for the bridge were obtained. Finally, the seismic responses of the bridge under three different constraint structures, namely conventional constraint system, seismic isolation system of friction pendulum bearing, and rigid frame bridge system, were compared. The results show that the friction pendulum bearing can effectively reduce the seismic internal force response and control the actual displacement response within a reasonable range under the transverse or longitudinal seismic input, which proves the effectiveness of the system for the bridge.
Calculation of arch rib installation alignment of large span cable hoisting arch bridge
XIONG Shaohui, GUO Xin, and YOU Zuoqiao
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.017
Cable hoisting method is the most important construction method for long-span arch bridges. In the process of arch rib lifting, the partial consolidation of the joint caused by temporary bolt connection, the deflection of the tower caused by the temporary construction load of the main cable, and the free expansion of the anchor cable and the buckle cable caused by temperature change will have a great influence on the installation alignment of the arch rib. In this paper, a two-element model method considering stiffness loss was used to calculate the correction value of the arch rib installation alignment more accurately when considering the partial consolidation of arch rib joints. Based on the geometric relationship between cable and tower, the calculation formula of tower deflection and free expansion of anchor cable and buckle cable caused by temperature change was derived, and the correction value of tower deflection and temperature change of anchor cable and buckle cable on arch rib installation alignment was calculated. Finally, the arch rib installation alignment of the long-span cable-hoisted arch bridge was calculated according to the formula that considered the influencing factors. By taking the Lancang River Bridge in Yunnan Province as an example, the arch alignment error meets the standard requirements.
Correlation analysis between external damages and transverse load distribution capacit y of hollow slab bridges
CAO Hao, SUN Dunhua, WANG Zichen, ZHAO Fuli, SUN Haipeng, and XIONG Wen
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.018
To correctly evaluate the service status of prefabricated hollow slab girder bridge, based on the measured data of apparent disease and load test of hollow slab girder bridge in reconstruction and expansion project, this paper first analyzed the data characteristics of the beam body, hinge joints, and support disease samples and obtained their statistical distribution rules. Then, according to the typical diseases (transverse cracks and hinge cracks at the bottom of the beam), the BP neural network was used to build a correlation model for them, and the close correlation between the two typical diseases of hollow slab girder bridge was proven. The transverse force transfer performance of hinge joints was used as the evaluation index of the transverse load distribution ability of the hollow slab girder bridge. Based on the difference between the measured joint height and the theoretical joint height in good condition, an evaluation index of hinge joint damage degree was established. Finally, based on the field bridge detection, test, and finite element simulation data, the neural network model of “apparent disease–transverse load distribution ability” correlation analysis was constructed. The results show that the neural network model can be used to evaluate the transverse load distribution ability of hollow slab girder bridges based on apparent disease and has good engineering practical value.
Thickness detection of reinforced concrete protective layer based on environ mental calibration
HONG Hua, XU Jianhong, CAO Sugong, and FU Junlei
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.019
In order to solve the problem of inaccurate detection of reinforced concrete protective layer thickness in engineering, this paper studied and formed a reasonable and perfect method and calibration procedure for the detection of reinforced concrete protective layer thickness in highway and water transportation engineering by using the analysis of influencing factors. The results show that the accuracy of measuring the protective layer thickness of reinforced concrete in practical engineering can be effectively improved. The production of standard instrument calibration specimens can be saved, and the testing process can be standardized.
Analysis of installation method and error control of steel girder of steel ⁃concrete composite girder cable ⁃stayed bridge
XIONG Xianyong, FU Yajun, and HUANG Gen
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.020
Compared with cable-stayed bridges with pure steel girders, the installation of a steel main girder of the steel⁃concrete composite girder cable⁃stayed bridge is more complicated, and the installation error control is more difficult. In this paper, the composite girder with a double box section was taken as the research object, and a finite element model was established to compare the installation methods of steel main girders. The best installation method was selected according to the principle of safety loading, and the causes of the installation errors of steel main girders were analyzed. The corresponding error control methods were proposed.
Research of disease analysis and reinforcement technology for typical orthotropic bridge deck
GUO Fukuan and ZHOU Shangmeng
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.021
In order to effectively solve the disease problem of orthotropic steel bridge decks, this paper relied on a steel box girder cable-stayed bridge deck reinforcement project to carry out steel bridge deck disease analysis and reinforcement technology research. The results show that the main disease of steel bridge decks is fatigue cracking. The fatigue cracks are numerous, short, and deep, and they continuously grow and cause more severe disease. The excessive fatigue stress amplitude is the main factor leading to the fatigue cracking of steel bridge decks. Once the crack occurs, the stress amplitude of the crack tip increases continuously, and the crack will continue to expand. Theoretically, the improved ultra-high performance concrete (UHPC) reinforcement scheme can reduce the fatigue detail stress amplitude and crack tip stress amplitude of steel bridge decks by 86.4% and 92.6%, respectively (both of which are below the fatigue limit of normal amplitude). After actual bridge reinforcement, the fatigue stress amplitude of the steel bridge deck is significantly reduced, and the fatigue disease is effectively alleviated.
Cable⁃stayed bridge of cable auxiliary beam arch pylon ⁃key technologies design of meishan minjiang bridge
MA Zhendong, LAI Yaping, and CHEN Jiayong
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.022
The newly built Minjiang Bridge in Meishan City, Sichuan Province applies the concept of cable-assisted girder bridge. P4 steel arch tower combined with three-stage balanced double-plane cable and P3 and P5 auxiliary towers combined with thin cable of single cable plane were used to assist the load on the beam body, making the 2.5 m-high concrete main beam meet the requirements of the main span of 2 × 120 m. Through the analysis of the bearing force, the angle between the double-limb arch tower was 43.6°, and two pairs of cables were set in the auxiliary tower to achieve the design purpose of balanced load on the beam body and the steel arch tower. The restraint system adopted the P4 arch tower for tower and beam separation and P3 and P5 auxiliary towers for tower and beam consolidation and pier and beam separation. The whole 8-span bridge totalling 500.5 m was an integrated layout, achieving comprehensive optimal performance such as structural safety, driving comfort, and convenient maintenance in the later period. The main girder was designed with a one-box four-chamber flat concrete box girder according to the full prestressed structure. Edge anchorage and web anchorage were adopted on the main girder for the main tower and auxiliary tower cable, respectively. P4 double-limb steel arch tower used a rotary hinge and “synchronous symmetrical vertical rotation” construction method to rotate the joint arch platform into place and constituted the bridge through the concrete joint section and the special-shaped tower in the concrete space.
Aesthetic design of hechuan qujiang landscape bridge
ZHENG Guangqin, CHEN Jiayong, LI Yue, LAI Yaping, and QIAO Yunqiang
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.023
Hechuan Qujiang Landscape Bridge is located at the junction of Qujiang River and Jialing River. It is a 1 × 400 m simple supported single-cable surface ground anchor suspension bridge. The main girder is a steel box girder arranged with curved branches. One side is the highway system to meet the needs of motor vehicles across the river, and the other side is the greenway system to meet the needs of pedestrians and non-motor vehicles. In the design process, the aesthetic design of the bridge was fully studied from four aspects: environment aesthetics, structure aesthetics, function aesthetics, and form aesthetics. Based on the surrounding environment of the bridge site, the ground anchor suspension bridge was selected. Based on mechanical topology, the bridge tower was designed as a triangular arch. The main girder adopted a curved branch layout to meet the needs of road exhibition lines according to local conditions and realize the leisure, ecological, and humanized design concept of human and vehicle separation. The overall shape of the triangular arch bridge tower and the curved branch layout of the main girder is novel, simple, and smooth, which fully reflects the flexible application of the aesthetic design of the bridge.
Study on optimal layout of cross ⁃diaphragm in oblique small box girder
MAI Xinhao
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.024
In order to determine the optimal layout of the cross⁃diaphragms in the oblique small box girder, a prestressed concrete small box girder bridge with a 50 m span was taken as the research object, and its internal force under the load of the moving beam was numerically simulated and measured. First, the model was modified according to the measured stress data, and the maximum distance between the cross⁃diaphragms was determined by using the warping-limited normal stress. Then, the height and thickness of the middle cross⁃diaphragms were determined according to the deflection difference coefficient of the bridge span. Finally, according to the variation law of deflection of small box girder, the optimum number of cross⁃diaphragms was analyzed. The results show that the maximum distance between the middle cross⁃diaphragms is 13.1 m, and the setting of 1–2 middle cross⁃diaphragms will lead to excessive warping normal stress of the box girder due to excessive spacing. In the case of meeting the structural requirements, the larger height of the cross⁃diaphragms indicates smaller strain and better transverse distribution of load. With the increase in the thickness of the middle cross⁃diaphragms, the transverse load distribution effect is enhanced, but the too-large thickness will increase the dead weight of the bridge. With the increase in the number of middle cross⁃diaphragms, the transverse and longitudinal load distribution effects are enhanced, but in view of the influence of the dead weight of middle cross⁃diaphragms, increasing the number of middle cross⁃diaphragms will increase the deflection of the small box girder. In general, the installation of four middle cross⁃diaphragms is the most beneficial to the uniform stress of the small box girder and the stress of middle cross⁃diaphragms, and it meets the structural requirements. Further increasing the number of middle cross⁃diaphragms will significantly increase the deflection of the small box girder.
Non⁃gaussian features of fluctuating wind pressures under combined axle condition
CHEN Zhiqiang
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.025
In view of the non-Gaussian characteristics of wind pressure on the train surface of a typical high-speed railway train and bridge system, the Gaussian variable was expressed as a Hermite polynomial considering non-Gaussian variables by using Hermite series expansion method, and the probability density curve and peak factor of train surface were analyzed. The results show that the Davenport peak factor based on Gaussian distribution obviously underestimates the non-Gaussian peak factor, and its probability density curve deviates from the actual curve of the measuring point. The Hermite series peak factor method based on the modified method takes into account the characteristics of kurtosis and skewness of the wind pressure at the measuring point and is the closest to the observed peak factor.
Design and construction of steel caisson for inclined pilecap of beitstadsund bridge in norway
YANG Dingjun
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.026
At present, the underwater bridge foundation construction technology in China and abroad has been relatively mature, but the different geographical environments, hydrogeological conditions, the form of basic structure, and the available construction equipment lead to different construction schemes and technologies. The Beitstadsund Bridge in Norway is located near the Arctic Circle in central Norway and across the strait. In the design and construction of the deep-water steel cofferdam of the inclined steel pile cap for the bridge, the overall installation of the steel cofferdam was realized by setting the cofferdam support on the inclined steel pipe group, the overall positioning and installation of the cofferdam, the steel-concrete composite plate bottom sealing, and the vertical anti-floating rock anchor. The application results of the bridge show that the steel cofferdam design and the overall installation process have better safety and practicability.
Application of 3D reconstruction model in inspection of bridge apparent defects
XU Guangli, LI Shaoyong, TANG Jun, LIU Shuqi, and ZHOU Yin
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.027
In view of problems such as low efficiency, poor accuracy, and imprecise three-dimensional (3D) location of defects in apparent defect inspection of bridges, this paper proposed a method for apparent defect inspection of bridges based on a 3D reconstruction model. By taking the indoor rectangular beam as the object, a three-dimensional bridge model was established, and its accuracy was verified. Then, based on the point cloud data derived from the model, a program was written in Python to realize the identification, measurement, and parameter derivation of apparent defects of bridges. Dade Bridge in Kunming, Yunnan Province was set as the background, and the whole-process project application was carried out. The results show that the method can focus on the automatic detection and location of apparent defects of bridges, significantly improve the inspection efficiency, visualization, and automation degree, and have a good application prospect.
Study on correction method of cable length error in construction control of cable ⁃stayed bridges
HUANG Gen and CHEN Changsong
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.028
In order to effectively correct the stay cable length error during the construction of the cable-stayed bridge, this paper proposed a correction method with the exposure of the sockets as the error control index and analyzed the influence of the elastic modulus, temperature effect, and anchor point coordinates of the cable on the cable length error from the perspective of construction control. Then, error correction was achieved by adjusting the position of the manufacturing cable length and the nut at the anchor end. The results of application in Jiayu Yangtze River Highway Bridge show that this method can improve the consistency between the actual amount of sockets and the theoretical value after the completion of cable tension, make the nut in the effective thread area of the sockets, and ensure the efficient implementation of the installation and tension of the cable during the cantilever erection of the main beam of the bridge.
Analysis of mechanical and deformation characteristics of karst tunnel structure and research on treatment technology
HUANG Haifeng, CHANG Zhenchao, LUO Junhui, ZHOU Xiang, CENG Fuquan, and TIAN Fapai
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.029
Combined with the construction process of Nongmo Karst Tunnel on Du’an–Bama Expressway, this paper used Midas-GTS finite element calculation software to conduct numerical simulation research on the stability of surrounding rock and treatment structure of tunnel with karst caves on either side, analyzed the influence of tunnel excavation on the stress and deformation characteristics of surrounding rock and supporting structure, and probed into the treatment effect of biased wall and root pile on the treatment of karst tunnel. The results show that the surrounding rock at the bottom of the tunnel, the top of the composite foundation, and the top of the pile foundation all bulge during tunnel excavation. The horizontal displacement rate of the biased wall near the karst cave varies greatly, and the maximum compressive stress of the biased wall appears in the upper left corner. Special attention should be paid to the stability of this part during tunnel excavation. After the completion of tunnel excavation, the displacement and stress of the treatment structure and surrounding rock tend to be stable, and the treatment scheme of the biased wall and root pile has a good effect.
Influence of proximity construction of a new pile foundation on adjacent metro tunnel
JIN Shengji, MU Anxin, BI Bo, XU Chao, and YU He
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.030
The construction of a bridge pile foundation and cap not only causes disturbance to its foundation and surrounding soil but also has a certain influence on adjacent existing structures. In order to study the influence of new pile foundation proximity construction on tunnels adjacent to subway sections, this paper took the pile foundation construction process of auxiliary bridge extension on both sides of Shenyang Changqing Bridge as the research object and adopted Midas/GTS finite element numerical simulation and construction monitoring methods to study the influence of new pile foundation proximity construction on tunnels adjacent to subway sections. The results show that: ① In the construction process, the vertical settlement and horizontal convergence of subway tunnel generally show the trend of subsidence and inward convergence, and the settlement caused by it is more obvious; ② The deformation characteristics of subway tunnel are related to various factors, but the influence of the clear distance between adjacent structures is the most significant. A small distance from the construction area indicates greater deformation; ③ In the selection of the construction scheme of straddle pile layout and unilateral pile layout, according to the comparison of the maximum settlement value of the tunnel arch, the impact of straddle cap on the tunnel arch displacement is less, and the safety of the tunnel construction near the subway section is easier to be guaranteed. The research shows that in the close range of existing structures, the construction of new structures must ensure sufficient safety distance and take effective safety measures to reduce the impact.
Pavement Structure and Materials
Research on crack and permeability characteristics of cement ⁃modified expansive soil under dry ⁃wet cycles
BAO Guiyong, XU Yangshaojun, JIANG Zhijie, RONG Hongliu, and WANG Jinlong
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.031
In order to study the engineering permeability characteristics of cement-modified expansive soil under dry and wet cycles, the mix ratio of cement-modified expansive soil was designed, and the orthogonal design test method was adopted. Image analysis software PACS, unconfined compressive strength test, and laboratory permeability test were used to study the crack development, strength attenuation characteristics, and permeability changes of cement-modified expansive soil under dry and wet cycle conditions. The results show that soil permeability and strength are greatly affected by the number of dry and wet cycles. Under the condition of dry and wet cycles, the moisture content of cement-modified expansive soil is more stable, and the crack resistance, strength, and permeability are obviously improved. The fracture rate, strength attenuation rate, and permeability of low-alkali cement soil are higher than those of ordinary cement soil.
Study on influence of freeze ⁃thaw cycles on shear properties of fly ash modified saline soil
CHENG Zhuo, CUI Gaohang, GAO Zening, HOU Zhao, and GANG Haohang
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.032
In order to explore the shear strength of fly ash-modified saline soil subgrade under the freeze-thaw cycle, saline soil samples from Suihua–Daqing Expressway were selected for direct shear test under different fly ash contents. The results show that the cohesive force and internal friction angle of the saline soil decrease after several freeze-thaw cycles. With the increase in fly ash content, the internal friction angle, cohesive force, and shear strength of the improved saline soil increase first and then decrease. When the fly ash content is 15%, the cohesive force, internal friction angle, and other mechanical indexes of the saline soil sample reach the maximum. In the process of subgrade construction in the Suihua–Daqing Expressway area, 15% fly ash can be added to subgrade soil to improve the shear strength and the ability to resist the freeze-thaw cycle.
Effect of temperature and light on characteristics of asphalt emissions
ZHU Xuwei and TIAN Bo
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.033
In order to study the effects of temperature and light on the characteristics of asphalt emissions, atmospheric pressure chemical ionization–time-of-flight mass spectrometer (APCI‑TOF MS) and electron impact ionization mass spectrometry (EI‑MS) were used to quantitatively characterize the composition information of PG 62-22 asphalt emissions at different temperatures (40–200 °C). The effects of different temperatures and light on total emission factor, SOA conversion factor, intermediate volatile organic compound (IVOC)/semi-volatile organic compound (SVOC) volume fraction, and aromatics volume fraction of asphalt emissions were studied. The results show that the components of asphalt emissions change with temperature, and the components are complex and varied, including anthracene, naphthalene, pyrene, fluoranthrene, and other harmful substances to the human body and environment. The emission factor and SOA conversion factor of asphalt increase with the increase in temperature. When the temperature is lower than 140 °C, the emission factor and SOA conversion factor of asphalt have strong temperature sensitivity. With the increase in temperature and light duration, the proportion of IVOC gradually decreases, and the proportion of SVOC gradually increases. The light causes the asphalt to release more PAHs.
Study on triaxial mechanical properties of glass fiber reinforced cement soil in short age
WANG Wei, DAI Mengdan, and YU Wenjie
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.034
In order to evaluate the improvement effect of fiber on the brittle damage of cement soil, a triaxial unconsolidated undrained (UU) test was carried out on glass fiber cement soil (GCS) with a curing age of 7 d and a mass fraction of glass fiber (GF) of 0, 2‰, 4‰, 6‰, and 8‰, respectively. The results show that: ① GCS retains the original strain softening characteristics of cement soil; ② For the same mass fraction of GF, the peak stress, peak strain, and residual strength of GCS samples increase gradually with the increase in confining pressure, but the brittleness index IB decreases gradually. ③ When the confining pressure is constant, the peak stress, peak strain, residual strength, and brittleness index of GCS samples are the best when the mass fraction of GF is 4‰. ④ The internal friction angle and cohesive force of modified cement soil with the optimum fiber content are increased by 8% and 50%, respectively, compared with that of plain cement soil, indicating that the modification of cement soil by GF is mainly achieved by improving cohesive force. The results show that it is feasible to modify coastal cement soil with appropriate GF to improve its brittle damage.
Study on experimental application of xinjiang steel slag in cement stabilized base
CHEN Wei, YU Haiming, LI Qian, HUANG Yong, and SI Yi
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.035
Based on the experimental study of Xinjiang steel slag in cement-stabilized base, the physical and chemical characteristics of steel slag were analyzed, and the unconfined compressive strength, splitting strength, and dry shrinkage performance of cement-stabilized steel slag and gravel mixture with different cement dosages (4% and 5%) and steel slag contents (30%, 40%, and 60%) were analyzed. The test results show that steel slag can be used as a good engineering aggregate in a cement-stabilized base, and with the addition of steel slag, the unconfined compressive strength and splitting strength of steel slag and gravel mixture are increased to varying degrees, and the dry shrinkage deformation decreases with the increase in the proportion of steel slag, indicating that steel slag has a compensation effect on the dry shrinkage deformation of the cement-stabilized base. According to the engineering application, the modified EDTA formula V = V1 -V2-V3×P is proposed, which can accurately detect the cement mixing amount, and the analysis shows that the inclusion of steel slag in the base has certain economic benefits.
Research on cyclic accumulative strain characteristics of structured soft clay
DING Zhi, YU Jiangang, SUN Miaomiao, WANG Jiawei, and YE Ke
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.036
Due to its structural properties, natural soft clay is prone to produce large cumulative deformation under cyclic loads such as traffic, which has a great impact on engineering. In order to solve the deformation problem caused by structural failure of soft clay under dynamic action, dynamic characteristics of undisturbed soft clay near a highway in Hangzhou were tested by the dynamic triaxial device under cyclic loading, and the dynamic characteristics of saturated undisturbed soft clay under different effective consolidation confining pressures, vibration frequencies, and dynamic stress ratios under K0 (static earth pressure coefficient) consolidation conditions were studied. The results show that under the same test conditions, the axial strain develops faster under the action of low effective consolidation confining pressure, low vibration frequency, and high dynamic stress ratio. By considering the effect of effective consolidation confining pressure, vibration frequency, and dynamic stress ratio, the expression relation that can describe the axial cumulative strain of the soil sample is obtained, providing a basis for the deformation calculation and prediction of structural soft clay under dynamic loads such as traffic.
Experimental study on time ⁃varying characteristics of saturated water content of granite residual soil in acid⁃etched environment
ZHANG Maolin, XIE Qingzhong, FU Helin, ZHANG Meng, LI Qinglong, and DONG Hui
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.037
In order to clarify the correlation between saturated water content variability and slope stability, characteristic tests on saturated water content of granite residual soil affected by acid were carried out. Direct shear tests were carried out to test the variation rule of saturated water content and its characteristic value under the influence of vertical loading and acidification time, and the internal causes of variation were deduced based on the structural characteristics obtained by microscope electron microscopy. The results show that: ① The vertical pressure σ = 300 kPa is the turning point of the linear and nonlinear relationship, and under the same vertical pressure, the acidification time is positively correlated with the saturated water content; ② The ion exchange efficiency between the surface ions of mineral particles and the acid solution is the highest when pH = 4 for 30 days of acidification, so pH = 4 is the characteristic value of acidity that affects the saturated water content. When the water chemical reaction of the saturated sample under pH > 4 is almost finished, there is a peak saturated water content. ③ The microstructure reflects that the change of saturated water content under acid etching is mainly related to the cementation type. The cementation type pattern under different acidity and acidification time is summarized.
Effect of activator on compressive strength of steel slag powder cement soil
CHEN Fei, WANG Yanchun, and DU Sujun
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.038
In order to reasonably solve the environmental pollution caused by steel slag, steel slag powder was used to improve cement soil. The optimal mix ratio was determined by a laboratory unconfined compressive strength test to prepare steel slag powder cement soil. In view of of low activity and limited compressive strength enhancement effect of steel slag powder, three kinds of activators including sodium hydroxide, silica fume, and calcium chloride were selected to be added to steel slag powder cement soil, so as to study the strength variation rule. The results show that the strength of cement soil can be improved with different steel slag contents, and the compressive strength of cement soil can be improved better when the soil sample is mixed with an equal proportion of cement and steel slag powder. When 10% steel slag powder is mixed with different kinds of activators, the strength change trend is different. When the content of sodium hydroxide is 0.5%, the compressive strength reaches the maximum value. When the content of silica fume is 1.5%, the strength of the sample is improved obviously. The compressive strength of the samples decreases with the increase in calcium chloride content.
Mechanical properties and micro analysis of cement stabilized steel slag macadam base
WAN Tianbao
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.039
With steel slag as coarse aggregate, cement-stabilized steel slag macadam base material was designed and prepared by selecting three kinds of cement dosage and three kinds of steel slag content. The mechanical properties of cement-stabilized steel slag macadam base were studied through compaction and unconfined compressive strength tests, and XRD and SEM microscopic tests were carried out to analyze the mineral composition and microscopic morphology of steel slag and mixture and clarify the internal mechanism of hydration product formation and microstructure and strength formation. The results show that the maximum dry density and optimum moisture content of cement-stabilized steel slag macadam mixture gradually increase with the increase in steel slag content under the same cement dosage, and the unconfined compressive strength decreases. Compared with cement-stabilized macadam mixture, the strength reduction of cement-stabilized mixture with steel slag content of 50% and 100% is 8.8%–11.4% and 10.5%–15.9%, respectively. Microscopic analysis shows that steel slag contains a large amount of CaCO3, SiO2, iron, aluminum, and other metal oxides. The characteristic peaks of quartz (SiO2) and calcium silicate (Ca2SiO4) in cement-stabilized steel slag macadam mixture after curing for seven days are obvious. Meanwhile, the diffraction peaks of calcium silicate hydrate and calcium aluminate increase correspondingly, and hydration products such as C-S-H gel and ettringite gradually increase. The pozzolanic effect of steel slag is conducive to the formation of hydration product network structure.
Analysis of influence of moisture content ⁃temperature dual factor on mechanical properties of red clay
WANG Jiangtao, BAO Temenbaiyila, YANG Weiguang, ZHOU Qi, and FU Helin
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.040
Under the new climatic environment and engineering construction requirements, engineering problems involving red clay are becoming more and more prominent, and it is urgent to deeply grasp the mechanical and engineering properties of residual slope red clay. The typical red clay in Hunan Province was studied in this paper. Based on the unconsolidated undrained direct shear test, this paper studied the mechanical properties of residual slope red clay under the influence of moisture content and temperature, focusing on the most unfavorable conditions affecting the mechanical properties of red clay. The results show that: ① The shear strength of red clay decreases by 10%–40% with the increase in moisture content under the influence of single factor moisture content. By considering the influence of water content and temperature, the shear strength of red clay decreases with the increase in moisture content when the temperature increases. ② The cohesive force of red clay is affected by both temperature and moisture content. At the same temperature, the moisture content increases, and the cohesive force decreases by 40%–70%. Higher temperature indicates less influence of moisture content on the cohesive force. At the same moisture content, the cohesive force is the least when the temperature is 30 °C. ③ In the non-extreme temperature range (10–30 °C), the internal friction angle of red clay is mainly affected by temperature, and the internal friction angle increases by 5%–10% with the increase in temperature.
Influence of steel fiber and polymer emulsion on mechanical properties and microstructure of concrete
GUO Guanglei, SUN Shiqiang, LI Ying, ZHENG Yiwei, and MEI Yingjun
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.041
The microstructure and mechanical properties of concrete were improved by adding steel fiber and polymer emulsion. The working properties and mechanical properties of steel fiber concrete, polymer emulsion-modified concrete, and steel fiber polymer concrete were tested at 3 d, 28 d, and 90 d. Nitrogen adsorption test, mercury injection test, and density method were used to obtain the total pore volume, median pore size, and closed porosity of concrete. The influence of steel fiber and polymer emulsion on the microstructure and mechanical properties of concrete was analyzed. The results show that the compressive strength of concrete after adding steel fiber and polymer emulsion has a slight change, but the bending strength increases by 24.1%–69.5%, 34.3%–70.5%, and 3.4%–43.7% at day 3, day 7, and day 90, respectively, and the bending ratio changes from 6.37–8.34 to 3.99–5.93. The total pore volume, total specific surface area, average pore size, and median pore size of concrete decrease, and the closed porosity increases. The optimal content of steel fiber should be 0.6%–0.9%, and the optimal content of emulsion is 6%–9%. Steel fiber and polymer emulsion can effectively improve the toughness and microstructure characteristics of concrete, and the effect of their mixing is obviously better than that of a single material.
Effect of nano ⁃metakaolin on frost resistance of concrete
LI Zhenfa
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.042
The denudation per unit area, relative dynamic elastic modulus, mechanical strength, and fracture characteristics of concrete with different nano-metakaolin contents before and after freezing and thawing were studied. The results show that nano-metakaolin can significantly improve the freezing resistance of concrete, and the denudation per unit area and relative dynamic elastic modulus loss rate of modified concrete are significantly improved compared with the reference group. The mechanical strength and fracture properties of nano-mekaolin-modified concrete before and after freezing and thawing are higher than those of the control group, and the mechanical strength, fracture toughness, and fracture energy loss rate are smaller after freezing and thawing cycles. At the same time, they increase first and then decrease with the increase in nano-metakaolin content, and the peak cracking load of about 40% can be increased at 6% content of nano-metakaolin. After 60 freezing-thawing cycles, the compressive strength and flexural tensile strength of concrete are increased by 68.36% and 70.28%, respectively, compared with the control group, and the bearing capacity of concrete during fracture instability is still greatly improved compared with the control group.
Traffic Engineering and Management
Traffic conflict analysis of multila neexpressway based on simulation
CENG Yuekai, ZHOU Tao, and CHEN Yazhen
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.043
In order to prevent traffic accidents on multi-lane expressways, the VISSIM traffic simulation model was established based on three types of multi-lane traffic conflicts: mixed passenger and cargo type, separated passenger and cargo type, and separated main and auxiliary type. SSAM software was used to obtain traffic conflict data, and the form, quantity, and location of the conflicts were analyzed. The results show that traffic conflicts are the most under the mixed passenger and cargo type, which are mainly distributed in the upper 100 m range of the innermost lane, outermost lane, and deceleration lane. The traffic conflicts under the separated passenger and cargo type are mainly distributed in the vicinity of truck lanes and interchange entrances. The traffic conflicts under the separated main and auxiliary type are mainly distributed in the side roads and lane changeovers.
Construction and management practice of green highways in qinling mountains
GAO Shuohan, ZHANG Lei, ZHAO Fuqiang, WANG Dong, LI Gang, LIU Xuexin, and YAO Jialin
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.044
In order to practice the concept of green development and promote the transformation and upgrading of highways in Qinling Mountain areas, the paper took Taibai–Fengxian Expressway, a typical demonstration project of green highway in Shaanxi Province as the basis to explore the practical experience of green highway construction suitable for Qinling Mountain areas. The project is located in the hinterland of the Qinling Mountains, with a sensitive water environment, important ecological functions, and rich tourism resources. In addition, it adopts EPC mode. Through the all-round and whole-process implementation of the green concept, the project was planned and launched from the perspectives of protecting the ecological environment, promoting natural harmony, improving project quality, and advancing intelligent management and control. It also focused on integrated transportation and tourism development, expanded service functions, innovated management mechanism, and highlighted green construction supervision, and other aspects, so as to provide the experience of green highway construction in Qinling mountain areas, provide technical support for improving the construction of green highway system, and realize the harmony and unity of man, highway, and nature.
Risk analysis of highway nighttime maintenance operation based on SEM
FAN Jinhua, ZOU Leping, QI Shaoren, and TIAN Zhen
Date posted: 7-14-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.03.045
In order to analyze the factors affecting the risk of nighttime expressway maintenance operation and quantitatively assess the degree of influence of various factors on the risk of nighttime maintenance operation, this paper extracted five first-level indicators and 36 second-level indicators that affect the risk of operation through literature review, accident data, and questionnaire survey and built an evaluation system. The first-order and second-order confirmatory factor analysis models were constructed by using a structural equation model (SEM) based on 343 questionnaires of the nighttime maintenance operation risks. The results show that the driver factor has the greatest effect on the operation risk, followed by the operation area, vehicle, road, and environment. Among the five first-level indicators, except that the environmental impact on vehicles is not significant, the other indicators have significant impacts on each other.
