Volume 42, Issue 6 (2022)
Articles
Research on Orthogonal Test of MgO-Fiber Cement Soil′s Deformation Modulus
HU Qizhi, YU Yang, MA Qiang, and ZHUANG Xinshan
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.034
Appropriate amounts of MgO and fiber can improve the compressive strength of cement soil. In order to further study the mechanical properties of MGO-fiber cement soil, Minitab software was used to design an orthogonal test method, and sensitivity analysis and influence analysis were carried out. The change rules of deformation modulus of MgO content, fiber content, and fiber length were studied at three different levels. The regression equations of MgO content, fiber content, and fiber length with cement soil deformation modulus were obtained by using Matlab software to process the test data. The sample was tested by scanning electron microscope (SEM), and the image was processed by ImageJ software to analyze the change in microstructure. The results show that the degree of influence on the deformation modulus of MGO-fiber cement soil in descending order is MgO content, fiber length, and fiber content. In the test range, the optimum mixture ratio is 1.5% MgO content, 6 mm fiber length, and 0.5% fiber content. The regression equation of the deformation modulus of MGO-fiber cement soil is obtained, and its accuracy is verified. SEM observation and ImageJ software analysis show that the addition of MgO and fiber can improve the pore structure of soil and strengthen the connection between structures, so as to improve the mechanical properties of cement soil.
Experimental Study on Performance of Cast Asphalt Mixture Basedon Dry Modification
WANG Ming, LI Bo, BAO Guangzhi, and HU Deyong
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.036
Cast asphalt mixture is the most widely used material for the pavement of long-span steel bridge decks, and the special asphalt binder cannot be produced and used in small batches. The wet modification process is obviously not suitable for the production of the cast asphalt mixture during the operation and maintenance period. In this paper, according to the requirements of cast asphalt mixture and its binder, combined with the requirements of the dry modification process, the developed direct injection modifier was employed to conduct the mix design of cast asphalt mixture and tests of the fluidity, penetration and increment, low-temperature limit bending and tensile strain, and fatigue properties. The properties of cast asphalt mixture were compared with asphalt mixture produced by wet process. The results show that the properties of the cast asphalt mixture prepared by the dry process meet the requirements of the current specification, which is basically the same as that of the wet process, and the fluidity is relatively good; the high temperature strength and low temperature crack resistance are slightly lower. The fatigue properties of the two dry processes are significantly different, and the difference in fatigue times at 1 000 με is 50.7%, but they both are lower than that of the wet process. The internal damage of the two kinds of cast asphalt mixture is more and more independent, and the change ratio of dissipated energy Rw × 10−4 tends to [−1, 1], but the wet process is better than the dry process in the early stage.
Subgrade Engineering
An Overview on the "ReusePotential" for Managing Shield Tunnel Spoilsas Resource
ZHANG Junhui, LI Hai, YANG Hao, WANG Hualei, and HAN Shanpeng
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.001
In response to the challenges posed by massive shield muck production and inadequate disposal solutions, scholars have systematically reviewed the research on shield muck recycling technologies. Based on the challenges faced by the treatment of shield muck in China, this paper formed a systematic understanding of the classification of shield muck, the progress of resource recycling technologies, and typical applications, introduced the pretreatment methods of shield musk in China and abroad, and summarized the application scenarios and resource recycling technologies of shield musk in detail. Then, the paper analyzed the problems of shield musk recycling technologies, such as expensive curing agents, serious pollution, lack of pollutant analysis of roadbed backfill materials, low strength of recycled brick, and unconspicuous market benefit. The standardized technical process of “pre-classification treatment of shield musk, feasibility evaluation of recycling, resource recycling scenario, and performance and benefit evaluation” for shield musk recycling was constructed. The research directions of the development of shield musk curing agents and the migration of pollutants were emphasized. Finally, the development trend of shield musk recycling technologies was prospected.
Design Optimization of Pile Slab Wall Reinforcement Scheme for High Cutting Slope
YAN Qiong, CAO Zhensheng, WANG Meng, WU Shunchuan, and HAN Longqiang
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.002
The rationality of the reinforcement and support scheme for high and steep slopes formed by deep cutting of expressways, especially the reinforcement and support of large pile-slab wall structures, has been a common concern of scientific researchers and technical personnel in the field of highway subgrade engineering. In this paper, the right-side deep cutting slope in section K50 + 758.5–K50 + 850 of Jianshui (Gejiu)–Yuanyang Expressway project in Honghe Hani and Yi Autonomous Prefecture, Yunnan Province was taken as the research object. Based on the strength reduction theory and the normal, earthquake, and rainstorm conditions of slope construction, FLAC3D finite difference software was used. By comparing the slope stability indexes such as slope safety factor, maximum slope displacement, axial stress of anchor rod (cable), and shear strain increment cloud map before and after the design optimization, the design and analysis models of high cutting slope reinforcement were optimized. The calculation results show that the slope can eliminate the reinforcement and support structure of pile-slab walls, and the scheme meets the dual indexes of rationality and benefit. Finally, combined with the stability monitoring data of the slope and the reinforced structure, it is verified that the optimization scheme conforms to the low-carbon concept and has obtained remarkable economic benefits.
Dynamic Response of Tunnel Under-Crossing Heavy-Duty Railway Subgrade Based on Coupled Load
DONG Jie, YANG Bo, and LI Chengxian
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.003
In order to reveal the effect of coupled dynamic load on the underpass tunnel of a heavy-haul railway roadbed, finite difference software FLAC3D was used to establish a three-dimensional numerical model of the underpass railway roadbed structure of the expressway tunnel with different clear distances and different crossing angles, and the vibration load of the heavy-haul train was simulated by excitation function. With the El Centro wave as the input seismic wave of the model, the acceleration, displacement, and maximum principal stress response characteristics of the lower tunnel under coupled dynamic load were analyzed, and the influencing factors were analyzed by sensitivity analysis method. The main conclusions are as follows: ① Considering the action of heavy-duty trains above the tunnel under the earthquake will have a more serious impact on the safety of the tunnel. ② With the increase in the clear distance, the peak value of acceleration and displacement at the monitoring points of the tunnel decreases, and the peak value of maximum principal stress increases. ③ The crossing angle only affects the affected range of the lower tunnel and has little effect on the peak value of the maximum principal stress. ④ It is recommended that when similar projects are designed, the clear distance should be considered first, followed by the crossing angle, and the clear distance and the crossing angle should be increased as much as possible.
Soil Arching Effect of Pile Supported Emban kmentand Evolution Law of Bearing Characteristics
HUANG Zebin, XIE Zhiwei, LU Jun, LIU Xianlin, and LV Xilin
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.004
The pile-supported embankment is widely used for subgrade settlement control in soft soil areas. Analyzing the soil arch effect of the embankment is the key to obtaining its bearing and deformation characteristics. Physical model tests of the soil arch effect and three-dimensional elastoplastic finite element numerical simulation of pile-supported embankment were carried out to study the soil arch formation process and bearing characteristics in embankment under the condition of differential settlement of pile and soil. The results show that with the increase in the differential settlement of pile and soil, the stress distribution in the embankment changes constantly, and the vertical pressure at the top of the pile first increases, then decreases, and tends to be stable, while the vertical soil pressure between piles decreases continuously until it becomes stable. When the soil arch is completely formed, there is an equal settlement surface in the embankment. The settlement of the soil layer on this surface is uniform, and that of the soil layer below this surface is uneven. The vertical distance between the equal settlement surface and the pile top is about two times the difference between pile spacing and pile width.
Study on Performance Comprehensive Evaluation and Reconstruction Technology of Old Roadin Soft Foundation Section
CEHN Zhongyun, WANG Jia, and HUANG Hongming
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.005
The soft foundation section has the characteristics of poor geological conditions and large settlements, so it has attracted much attention because of the difficulty of its later reconstruction. Based on the old road reconstruction project for the west expansion of the Baijin Line of Foshan First Ring Road, this paper classified the road section by monitoring and analyzing the settlement law of the soft foundation section and evaluating the technical condition of the old pavement, and it put forward three kinds of reconstruction schemes according to local conditions, such as leveling and paving, reinforcing and thickening, and pre-throwing. The testing data after completion show that the overall performance of the pavement is excellent, and the proposed classification treatment and reconstruction scheme is reasonable and effective.
Development and Test Evaluation of New Porous Elastic Low Noise Pavement
HE Xin, WAI Runhua, XU Li, and PENG Huiting
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.006
In this paper, a new type of noise-reducing pavement, porous elastic low-noise pavement, was developed, and the effect of voidage and elasticity on noise reduction was studied experimentally. Three kinds of standard test pieces of mixed material-derived rutting plates with different voidage gradations were designed, and the laboratory tire acceleration fall test and damping vibration and noise reduction test were carried out. The results show that the porous elastic low-noise pavement has better noise reduction ability than ordinary asphalt concrete pavement. The noise reduction ability of the two methods is strong, compared with that of the traditional densely graded AC-13 asphalt concrete. With the increase in the new material dosage, poly olefin elastomer (POE), the system damping of tire/road becomes larger. The enhanced vibration and noise reduction ability can provide a suitable theoretical reference for the application of POE materials and pavement engineering in the aspect of noise reduction.
Competitive Study on French Standard Axial Load Conversion and Pavement Structures with Various CCAM Values
WANG Yanping
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.007
French standards are widely used in European countries and Francophone countries in Africa, and many overseas projects in which Chinese engineering companies participate adopt French standards. The average axle load conversion coefficient (CCAM) is a key parameter in the calculation of pavement structure. The CCAM value under different input conditions may greatly affect the pavement structure scheme and structure thickness. By analyzing the method of axle load detection and axle load conversion in the French standards, this paper proposed three methods for determining CCAM in French-speaking African projects: using the standard reference value, calculating by axle load detection, simplifying the calculation with reasonable assumptions of representative vehicle type and overload level. By taking a project in Mali as an example, the comparative analysis and inverse fatigue life calculation of inverted pavement structure under different CCAM values were carried out, so as to provide technical reference for theoretical research in France and overseas road projects adopting French standards.
Pavement Engineering
Influence of Void Size Beneath Airport Concrete Pavement and Pavement Life Analysis
DAI Xuan, CAI Jing, LI Xiangxiang, and YU Qi
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.008
In view of the problems caused by rigid pavement discontinuity at airports, a finite difference numerical analysis model was established considering pavement structure, joint, soil foundation, and the discontinuity body, and the influence of discontinuity size on pavement under different aircraft load positions and joint load transfer efficiencies was studied. The influence of discontinuity on the service life of pavement was analyzed by comparing Chinese and foreign codes. The results show that the bending of airport pavement structure caused by discontinuity is obviously affected by the temporal and spatial effects of wheel loads, and different displacement modes will be induced by discontinuity when the aircraft is located at different positions on the pavement. The bending tensile stress caused by wheel load in the upper part of the discontinuity area can reach two times that in the continuity area. The combined action of landing gear multi-wheel load and pavement discontinuity can significantly increase pavement stress, which leads to serious discontinuity damage. Improving the joint load transfer capacity has a positive effect on improving the influence of pavement resistance to discontinuity, and the initial discontinuity of pavement has the most obvious influence on its service life. The fatigue failure of the airport pavement structure is not only related to the surface concrete but also affected by the structural condition index of the base, soil foundation, and pavement. If only the fatigue failure of concrete structure is considered, the service life of airport pavement may be overestimated. In distress control, in addition to treating the discontinuity area, the joint load transfer capacity should be evaluated and enhanced to improve the overall performance of the airport pavement.
Application of BIM+3DGIS Technology for Expressway Pavement Maintenance
HU Honglong and ZHANG Shixiang
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.009
To apply BIM technology to highway pavement maintenance and management, firstly, the application scenario of highway pavement maintenance based on BIM technology was proposed. Secondly, the lightweight solutions of the BIM model were compared and selected. Thirdly, 3D GIS technology was introduced to study the technical route of integrating BIM + 3D GIS technology and the application scenario of highway pavement maintenance. Finally, the highway pavement maintenance management system based on BIM technology was developed to realize the application of BIM technology in pavement maintenance.
Research on Temperature Effect Model of Asphalt Pavement Rutting Tes
CHEN Shaowei
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.010
Experimental and Numerical Study on Steel Concrete Composite Section of Single Tower Cable Stayed Bridge
YANG Yongwei, LI Kai, DENG Lu, GUO Jinlong, and GAO Liqian
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.011
In order to provide guidance for the design of the steel-concrete combination section of a single-tower mixed beam cable-stayed bridge, a 1:4 scale test model of the steel-concrete combination section of the bridge was made based on the single-tower single-cable mixed beam cable-stayed bridge in Dongfeng Road, Siping City. The stress distribution of the combination section and the relative slip between concrete and steel under the action of axial force and bending moment were studied. The influence of five parameters, such as the thickness of the bearing plate, the diameter of shear nails, the diameter of perforated steel bars, the longitudinal spacing of shear nails, and the longitudinal spacing of perforated steel bars on the force transfer mechanism of the steel-concrete combination section was studied by finite element analysis. The results show that axial force and bending moment transfer smoothly in the combination section mainly in axial force mode and shear force mode. The stress level of each part of the combination section is within the allowable range, and it has a high safety reserve. The difference in local stiffness of the steel-concrete combination section leads to significant fluctuation of transverse stress. The axial force is mainly transmitted through the bearing plate, followed by shear nails and PBL shear keys, accounting for about 50%, 35%, and 15%, respectively.
Study on Transmission Alignment Error of Steel Girder in Cable-Stayed Bridge with Composite Beam
FU Yajun, LIU Hao, CHEN Changsong, and WANG Jing
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.012
In order to study the influence of the fabrication and installation errors of steel beams on the construction process of steel-concrete composite beam cable-stayed bridges and the alignment after bridge completion, based on the basic principle of unstress state control method, the error influence matrix of the unstress alignment of main beams in global and local coordinate systems was derived. The unstress length error of the steel main beam manufactured in the factory and the unstress curvature error caused by on-site installation were analyzed, and the transmission law of alignment error caused by them in construction was studied. The results show that the influence of the fabrication length error of the steel beam on the alignment of the subsequent beam segment accumulates with the construction process and is non-convergent. The influence of the angle error between beam segments on the elevation error decreases gradually with the progress of the construction and tends to be stable, exhibiting self-convergence. At the same time, it is verified that the steel beam length error has little effect on the cable force and the internal force of the steel beam in the composite beam cable-stayed bridge, but it has little effect on the internal force of the bridge deck.
Bridge Engineering & Tunnel Engineering
Analysis of Influence of Local Corrosion on Failure Mode of Q550EI-Beam
ZHOU Xu, WANG Guohua, WANG Qianqian, and PENG Jianxin
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.013
In order to study the effect of local corrosion on the degradation of mechanical properties of high-performance Q550E steel beam, a model of corroded high-performance steel (HPS) beam was established by using the wall thickness reduction method, and the ultimate bearing capacity of the HPS beam was calculated by using the arc length method on the basis of considering the geometric initial defects and residual stress distribution of the beam. At the same time, according to the existing test results, the practicability of the model in the research on the bending degradation of corroded HPS I-section beams was verified. On this basis, the corrosion parameters of the top plate, web plate, and bottom plate of the HPS beam were analyzed. The simulation results show that the main failure mode of the simulated beam is the local buckling of the compression flange plate. The corrosion of the top and bottom plates does not change the failure mode of the corroded beam, and the residual ultimate bearing capacity of the corroded beam is linearly related to the corrosion degree of the top plate or bottom plate, in which the corrosion of the top plate has a greater effect on the performance degradation of the HPS beam than that of the bottom plate. When the corrosion degree of the web plate reaches 30%, the failure mode of the corroded beam changes, and the bearing capacity decreases rapidly.
Study on Mechanical Properties and Design Methods of Asymmetrical Continuous Girder Bridges
ZHANG Zheghao, GUO Fengshi, and PENG Jianxin
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.014
This paper introduced the calculation and analysis of the asymmetric long-span box girder and the design measures taken. To solve the problems of unbalanced radio of spans and difficult structure layout of the box girder, the design method of asymmetric continuous beam bridge was proposed. The force analysis of the box girder was carried out, and the mechanical responses of the structure under different working conditions were compared. The results show that the structure of the asymmetric box girder is reasonable, and the force is greatly improved, which can provide a reference for similar structure designs.
Research on Toughness and Crack Resistance of BridgeConcrete Modified by Waterborne Epoxy Resin
LIN Zhe, GOU Baoming, GUO Yingchuan, ZHOU Xiaohan, WEI Xin, and YIN Lei
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.015
Ordinary bridge concrete has low flexural tensile strength, great brittleness, and poor toughness. Under the action of driving load, the bridge structure is prone to cracking and fails to meet the requirements of modern traffic for bridge engineering. Therefore, it is urgent to improve the cracking resistance of bridge concrete. As a water-soluble polymer, water-based epoxy resin not only has the characteristics of traditional epoxy resin, such as strong bonding force, water resistance, acid and alkali corrosion resistance, erosion resistance, and good impermeability but also does not contain organic solvents and other pollutants. Its application in bridge concrete can effectively improve the flexural tensile strength and flexural toughness of concrete, thus solving the problem of cracking of bridge concrete and increasing the service life of bridge structures. In this paper, the flexural tensile strength and three-point bending test of water-based epoxy resin-modified concrete were designed, and the toughening effect was evaluated by strength (flexural tensile strength and bending toughness coefficient), deformation (deflection), and energy (fracture energy), and the cracking resistance effect was verified by plate-induced cracking test. Finally, the toughening and cracking resistance mechanism of water-based epoxy resin-modified concrete was elucidated through microscopic analysis. The test results show that the addition of water-based epoxy resin can effectively improve the flexural tensile strength, bending toughness, and fracture energy of concrete. Compared with that of ordinary cement concrete, the 7-day flexural tensile strength of water-based epoxy resin-modified concrete can be increased by 20.4%, and the bending toughness and fracture energy can be increased by up to 42.7% and 51.8%, respectively. Water-based epoxy resin can improve the cracking resistance of bridge concrete by improving pore structure, microfiber, and water retention.
Optimization of Main Girder Hoisting Sequence of Asymmetric Long-Span Suspension Bridge
XIONG Shaohui, QIAN Feng, CHENG Junwei, and LI Yang
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.016
With the appearance of asymmetric long-span suspension bridges, it is necessary to study the optimization of the hoisting sequence of the main beams of this type of suspension bridges. By setting the maximum allowable value of the main tower deviation and the target alignment of the main tower, the method flow of optimizing the hoisting sequence of the main beams of the asymmetric long-span suspension bridge was given according to the relationship between the hoisting sequence of the main beams and the incremental launching scheme of the main tower. By taking an asymmetric long-span suspension bridge in Guangdong as an example, this method was used to optimize the hoisting sequence of the main beam, and good results were obtained and verified as follows. The hoisting of the main beam should be conducted from the middle span to the two towers, and the hoisting speed of the middle span should be consistent with the proportion of the number of standard beam segments of the middle span. The incremental launching scheme of the main tower should be formulated based on the maximum allowable value of the main tower deviation and the hoisting sequence of the main beam.
Key Construction Technologyon Cable-Stayed Bridge Girderswith High-Piers and Multiple-Towers
REN Lei
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.017
Chishi Large Bridge along the Rucheng–Chenzhou Expressway is a four-tower, double-cable plane, and prestressed concrete cable-stayed bridge with a span of (165 +3 × 380 +165) m, with the highest main tower of 286.63 m. The volume of the heaviest beam section 1# block reaches 269.2 m3, and the height difference between the main beam and the ground is about 185 m. The main beam of the bridge adopts five key technologies, including 0# block construction technology under multiple constraints, super-large front fulcrum bucket hanging construction with 7 600 kN bearing force, unconstrained closure technology of side span, incremental launching and closure technology of mid-span and sub-mid-span, vertical downstay cable +TMD main beam wind resistance research, to solve the technical problems of the construction of ultra-high and overweight prestressed concrete main beams of the bridge. It can provide reference for the construction of the main beam of the same type of cable-stayed bridge.
Analysis on Structural Strength of Anchor Box Based on Sub-Modeling
LI Datao, LI Yan, and LV Pengmin
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.018
The local structure of the outer web of a cable-beam anchorage area and the steel anchor box sub-model of a long-span cable-stayed bridge were established by using the sub-model modeling technology of Ansys software, and the structural strength analysis was completed. The results show that the stress concentration of the steel anchor box in the cable-beam anchorage area is serious, and the maximum stress value exceeds the yield limit of the material. Therefore, according to the stress concentration area of the steel anchor box structure, the local structure is optimized. The improved scheme obviously reduces the stress concentration of the structure, and the research results can provide a reference for the design of the anchor box structure of the same type of bridge.
Investigation and Analysis on Diseases of Asphalt Pavement of Concrete Continuous Beam Bridge
YANG Bo, CAO Weidong, GONG Weihua, ZHANG Zhidong, and TANG Wentao
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.019
In order to explore the distribution law and internal mechanism of asphalt pavement layer disease of concrete beam bridges, this paper studied four prestressed concrete continuous beam bridges with different degrees of asphalt pavement layer disease and used a new method of bridge deck pavement layer area division and disease statistics to carry out field investigation. Through the investigation and quantitative statistics of the disease distribution in each pavement layer area, as well as the finite element simulation analysis of bridge structural mechanics and pavement layer, it is found that most of the areas with serious diseases are areas with large tensile stress, shear stress, and vertical deflection, which indicates that the adverse mechanical response caused by load is an important internal reason for the bridge pavement layer disease.
Design and Application of Combined Grouting of Bored Pilesfor Highway Bridges
LIU Shichen
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.020
The combined grouting technology of pile foundation injects high-pressure cement slurry at pile tips and sides, effectively eliminating the inherent defects such as the sediment at the bottom of the traditional drilled pile and the mud skin of the pile body through the effects of the slurry penetration and splitting in the soil, and it enhances the strength of the soil at pile tips and sides, so as to improve the bearing capacity of the pile foundation and reduce the settlement of the pile foundation. In this paper, finite element software was used to numerically analyze the pile foundation with and without combined grouting, and the influence of combined grouting on the bearing capacity and settlement of the pile foundation was compared. The technical parameters of pile foundation grouting in JTG 3363-2019 Specifications for Design of Foundation of Highway Bridges and Culverts were taken as the design guidance. The reinforced coefficient of friction at pile tips and sides and the theoretical grouting amount were analyzed and determined, and the combined grouting design was carried out. The combined grouting test of the pile foundation was conducted to verify the design results and ensure the reliability of the design. The research results can provide a reference for the design and application of combined grouting in highway bridges.
Design of Cable-Stayed Bridge with Heteromorphic Arch-Shaped Pylon
LIU Zhaofeng, ZHANG Ming, and DAI Xiaodong
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.021
Benqiao River Bridge of Ziling West Road in Changde City adopts a (90 + 90) m single-tower double-cable plane cable-stayed bridge with a shaped arch tower. The main tower adopts a concrete arch tower. The alignment is a shaped curve composed of the catenary line segment and elliptical arc segment, and the tower height is 71 m. The main beam adopts a prestressed concrete double-ribbed main beam section with a width of 40 m. The cable-stayed cables on both sides are arranged through cables and anchored to the main tower through cable saddles, with friction pile group foundation. The finite element analysis results of the whole and local solid model of the bridge show that the structure is safe and reliable.
Research on Rational Structural Design of Orthotropic Composite Bridge Deck
LIN Weinan and YU Dongmin
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.022
In order to study the economy and reasonable structure of the orthotropic composite bridge panel, the loading modes of the most unfavorable position in the positive and negative bending moment zones under four kinds of live load were designed. The influence of U rib height, U rib center distance, and concrete layer thickness on the stress and economic performance of orthotropic composite bridge panel was analyzed by finite element method in four working conditions, and a reasonable structural dimension suggestion for a new type of steel-concrete composite bridge panel was obtained.
Study of Effective Length Factor of Suspension Bridge Tower in Longitudinal Direction
CHEN Guohong and SONG Xiaoli
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.023
The equilibrium differential equation of the longitudinal direction of a suspension bridge tower was established by using the static method, and the stability equation under vertical critical load was obtained by introducing the relevant boundary conditions. It is a transcendental equation concerning the effective length coefficient μ of the bridge tower and the ratio n of the longitudinal constraint stiffness of the tower top to the anti-thrust stiffness of the bridge tower. A calculation program was developed to obtain the numerical solution of the effective length coefficient of the bridge tower under different stiffness ratios, and a calculation table for design was made, with the simplified calculation formula fitted. It could be applied to the checking calculation of the bearing capacity of the suspension bridge tower under construction and completion and the force analysis of the compression column under similar constraints. The calculation results show that the cable system of the suspension bridge can greatly improve the longitudinal stability of the bridge tower. The longitudinal effective length coefficient of the bridge tower in the empty cable state is below 0.9, and the longitudinal effective length coefficient of the bridge tower in the completed bridge state is close to 0.7.
Finite Element Analysis of Pier-Tower-Girder Fixed Region of Cable-Stayed Bridge without Backstays
ZENG Kui and QIU Minjie
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.024
In order to study the mechanical behavior of the consolidation zone of the tower beam pier of the rotary cable-stayed bridge without backstays, a fine finite element model of the consolidation zone of the tower beam pier was established by using the finite element analysis method based on Shanban Bridge in Chengdu. The research results show that the longitudinal compressive members of the structure are under pressure during service; the longitudinal compressive stress on the main span side of the beam body is within −8.2 MPa (absolute value), and the longitudinal compressive stress on the side span side is within −14.0 MPa (absolute value). There is a large compressive stress reserve in the negative bending moment area of the main beam, and it meets the requirements of the standard. The longitudinal prestressed steel beam layout is reasonable. Under five working conditions, the transverse normal stress in the consolidation zone is −8.5–1.7 MPa, and there are some tensile stresses in the roof of the cantilever root of the small beam, all of which are less than 1.7 MPa, which can properly strengthen the transverse ordinary reinforcement layout. The bending moment of the bridge tower along the cable-stayed bridge without backstays under live load should be emphasized. In the stage of rotating construction, the axial force of the main beam is gradually transferred to the pier through the consolidation of tower pier beams, and the transfer process is stable.
Local Force Analysis of Steel-Concrete Joints of Long-Span Cable-Stayed Bridges Considering Creep Effec
CHUAI Honglei
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.025
In order to study the influence of the creep effect on the spatial stressed structure, the steel-concrete combination section of a cable-stayed bridge was set as the engineering background, and the stress–strain correlation was studied. The exponential creep degree function was selected to construct the stress–strain relation of concrete under the action of creep, and the newly constructed constitutive equation was embedded into the parametric model of Ansys APDL. The influence of the creep effect on the force of the steel-concrete combination section was compared. The results show that the creep effect can significantly change the force transfer mechanism of the combination section, reduce the direct force transfer effect of the bearing plate, and change the force transfer mode of the shear block. Under the influence of creep, the normal stress value of the combination section roof increases dramatically, and stress concentration occurs in the corner area of the shear block; the area of the high-stress area expands. Meanwhile, the creep effect changes the force transfer ratio of the shear block. By considering the creep effect, the total load assigned to the concrete on the same section of the steel-concrete combination section is higher.
Feasibility Analysis for Demolition Construction of Long-Span Truss Composite Arch Bridge
LI Qi, DU Bin, LIU Qi, ZHU Huadong, MA Zhengjia, LIU Lei, and CENG Guangfeng
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.026
A large-span prestressed concrete truss composite arch bridge to be demolished was studied. According to the idea of dismantling before building, the retrograde demolition construction scheme using the arch rib of a newly built concrete-filled steel tube arch bridge to assist the suspension of the arch ring of the old bridge was conceived. Combined with the stress characteristics and construction technology of this type of bridge, the demolition technology and construction key points of this type of bridge were discussed in detail. The finite element analysis software Midas/Civil was used to simulate the demolition construction process and analyze the stress and deformation of the structure in each demolition stage. The calculation results show that the scheme is safe, fast, and economical, and it can provide valuable experience for the subsequent demolition projects of similar bridges.
Design Featuresand Cast-in-Place Construction Technique of Support Methods of Continuous Box Girder for Mountain Road
LI Youming, BAI Xiohong, and WANG Qifu
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.027
According to the engineering environment and functional requirements of highway bridges in mountainous areas, the design characteristics of continuous box girder bridges with variable widths and the technical difficulties of cast-in-place construction by support method were analyzed. Based on the engineering environment and structural design characteristics, the technical feasibility, safety, operability, and economy of various support systems such as full-hall support, beam-to-column support, and combined support, hoop (steel bar) or bullleg support with pier, and floor mold were analyzed. The composite full-hall support and beam-to-column support scheme was scientifically and reasonably selected, and its construction quality control points were introduced. In view of the economic difference between the steel formwork and the wood formwork system, the wood formwork system was recommended, and the influence of internal mold removal on the bridge structure was analyzed. Based on the advantages and disadvantages of the first and second pouring schemes of box girder concrete, the technical countermeasures for the construction quality control of reinforcement, concrete, and prestress of continuous box girder bridges with variable width on mountainous highways were described in detail.
Study on Influence of Longitudinal Height Difference of Pierson Bridge Seismic Performance
WANG Qiang and ZHANG Yazhou
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.028
In order to improve the safety of bridges in western mountainous areas, the seismic response of longitudinal pier height difference to structures was studied. Firstly, the research case was clearly defined, and the simple supported and continuous structures under standard span were selected as the research objects according to the actual engineering demand and extension. Then, the response law of the structure under transverse and longitudinal earthquakes was studied by continuously changing the pier height of a span. Finally, based on the obtained structural response, the simplified bending moment curvature relation was used to judge the safety of the structure. The results show that the bending moment and axial force of the high pier are less affected by the height of the low pier. The bending moment of the low pier presents a quadratic curve, and the peak value appears before the equal-height pier. The axial force of the low pier presents a non-uniform increase due to the coupling effect of increasing dead weight and increasing inertia force. When the vertical pier height difference is within 5 m, special attention should be paid to the seismic response of the low pier under transverse and longitudinal earthquakes.
Study on Optimization of Rapidand Safe Construction of Urban Super-Small Radius Shallow Buried Spiral Arch Tunnels
GAO Feng, HUANG Lei, ZHANG Longxiao, and JIA Shan
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.029
Because of the complicated construction sequence, alignment, and the disturbance of excavation to the surrounding rock, the excavation sequence and supporting structure of small-radius shallow buried spiral multi-arch tunnels in mountainous cities are always a difficult point in the design. Based on the finite difference software FLAC3D, this paper simulated the dynamic construction process of a small-radius shallow buried spiral multi-arch tunnel and analyzed the spatial effect of the excavation face, the interaction between the left and right tunnels, and the stability of the middle partition wall from different construction sequences and excavation steps. The results show that when the small-radius spiral multi-arch tunnel is excavated first, the disturbance to the surrounding rock is smaller near the main hole. When the spiral radius is 30 m, the optimal construction step of the left and right tunnels is 1.5B (B is the tunnel half-span width). During the construction of the first tunnel, the middle partition wall deflects to the first tunnel, and during the construction of the rear tunnel, the middle partition wall deflects to the back tunnel. The displacement perpendicular to the direction of the middle partition wall is the largest, so it is necessary to strengthen and support the middle partition wall during construction to prevent overturning. The calculation results have a certain reference value for the design of small-radius shallow buried spiral multi-arch tunnels in mountainous cities.
Prediction Method of Grouting Volume for Treating Karst Cavesalong Tunnel Based on Fractal Theory
CUI Qinglong
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.030
The volume of karst caves is difficult to be determined in practice because of their scattered distribution and different shapes. To address this issue, fractal theory was used to find the fractal law of karst cave development along the tunnel. The fractal dimension of karst cave distribution was obtained according to the data of the geological survey report, and the volume of karst caves was calculated by using fractal parameters. Then, the proportional coefficient between the grouting quantity and the volume of the karst cave was obtained according to the grouting quantity of the karst cave on site, that is, the grouting quantity coefficient of the karst cave. Then, the grouting quantity of the whole area along the tunnel was calculated according to the volume of the karst cave and the grouting quantity coefficient of the karst cave. Based on the above research, a theoretical method and correction coefficient for estimating the grouting quantity of karst caves along the tunnel was proposed by using the data of the geological survey report.
Mechanism of Rubber Asphalts Viscosity Reduction by Warm Additives
JI Jie, MA Tong, REN Wanyan, YANG Yueqin, ZHANG Ran, ZHENG Wenhua, and SUO Zhi
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.031
In order to study the viscosity reduction mechanism of two types of warm mix agents (surfactants and organic waxes) on rubber asphalt, the functional group, micro and nano structures, and morphology of warm mix rubber asphalt were studied based on infrared spectroscopy, atomic force microscopy, and fluorescence microscopy. The results show that the surface-active warm mix agent can significantly increase the amide groups in rubber asphalt and interact with asphaltene and gum to form strong hydrogen bonds, and it can reduce the association force of asphaltene. At the same time, this kind of warm mix agent can form a structural water film on the surface of asphalt particles and rubber particles, resulting in a ball effect, thereby reducing the viscosity of asphalt. The organic wax warm mix agent forms a layer of the wax film by adsorption and wrapping around rubber particles and asphaltene. The lubrication, wrapping, and adsorption of this wax film can reduce the friction between asphaltene and rubber particles and reduce the viscosity of asphalt. The viscosity reduction mechanism of both surfactants and organic wax warm mix agents on rubber asphalt is realized by producing lubrication on the interface of rubber particles and asphalt particles.
Study on Raising the Mechanism of the Elastic Modulus of High Liquid Soil by Gravel Mixing
XU Shuliang
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.032
In order to make full use of high liquid limit soil and reduce waste, the mechanism of improving high liquid limit soil modulus by gravel was studied. Dynamic triaxial test, coarse aggregate gap rate test, and industrial CT scan were carried out to study the variation of modulus of gravel-modified high liquid limit soil from two aspects: gravel content and gravel gradation. The test results show that there is a critical value. When the gravel content is less than 43.8%, the soil is a suspension-dense structure, and the modulus growth is slow; when the gravel content is more than 43.8%, the soil is a skeleton-dense structure, and the modulus growth is faster. Gravel gradation tends to the lower limit, and the modulus increases with the increase in coarse aggregate content. The coarse aggregate inside the soil forms a skeleton through contact. With the increase in the coarse aggregate contact point, the skeleton structure is constantly improved, and the modulus is constantly increased and grows fast. The research can provide a reference for the rational utilization of high liquid limit soil.
Study on Effect of Particle Sizeon Permeability of Clay Sand
XU Zhaodong, LI Ming, HONG Changwei, and HU Qizhi
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.033
Clay sand is widely distributed in Binyang area of Guangxi, which is commonly used as subgrade filling material. Adding a certain amount of clay to soil can change the particle grading characteristics and obtain better filling effect, but it will affect the permeability characteristics of soil and thus affect the quality of subgrade filling. The inhomogeneity coefficient and curvature coefficient of sand with different clay contents were obtained by particle gradation test of sand mixed with clay. The variable head permeability test was carried out on the clay sand with different gradation indexes, and the relationship among the inhomogeneity coefficient, the curvature coefficient, and the permeability coefficient was obtained, respectively. The test results show that the permeability coefficient decreases with the increase in the inhomogeneity coefficient of clay sand. As the curvature coefficient increases gradually, the permeability coefficient increases. With the increase in the inhomogeneity coefficient, the limited particle size of the soil particles increases, and the particle size can be filled more under the same void ratio. Moreover, the pores are filled more fully, which further reduces the permeability coefficient and reduces the permeability.
Experimental Research on Mechanical Properties of Injected Red Clay
ZHANG Kai, LIU Yan, and PENG Shuigen
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.035
This paper studied the mechanical properties of red clay overlying karst caves before and after grouting, including its strength characteristics and dynamic characteristics. The internal friction angle φ and cohesion c of the red clay were analyzed by fast shear test. The critical dynamic stress, dynamic shear modulus, damping ratio, and softening index of the clay were analyzed by dynamic triaxial test. The test results show that without grouting, the red clay overlying karst caves is in a soft plastic state (liquid index I L = 0.9); the internal friction angle φ is only 21.1°, and the cohesion c is only 9.7 kPa. The red clay enters a hard state (I L = −0.4), and its shear strength is further improved after the grouting amount reaches 1 200 L and 10 days of curing. The increase in grouting amount is helpful to restrain the growth of axial cumulative strain and increase the critical dynamic stress of the sample, so as to improve the anti-vibration and anti-collapse ability of the red clay overlaying the karst cave and reduce the collapse of the soil cave. The increase in grouting amount also helps to improve the dynamic shear modulus, damping ratio, and softening index, thus reducing the damage degree of soil.
Prediction Model of Permanent Deformation of High Content Crumb Rubber/SBS Composite Modified Asphalt Mixture
ZHANG Qingyu, ZHANG Jiawang, and ZHAO Yi
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.037
Influence of Admixtures on Durability of Concrete in Corrosive Environment
ZHANG Aili, GUO Yanfeng, and SUN Hong
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.038
To study the evolution law of compressive strength, flexural strength, and erosion resistance of concrete under a corrosive environment, firstly, the corrosive environment was simulated with 3% Na2SO4 and NaCl solution, and then the performance change of concrete under the corrosive environment was analyzed by adding different contents of polypropylene fiber. The results show that: ① When the content of polypropylene fiber is 0–3%, the compressive strength and flexural strength of concrete gradually increase, and the maximum compressive strength and flexural strength of concrete in Na2SO4 and NaCl solutions are 50.2 MPa and 48.3 MPa, as well as 6.2 MPa and 5.8 MPa, respectively. When the content of polypropylene fiber is 3%–5%, the compressive strength and flexural strength of concrete gradually decrease. ② With the prolongation of corrosion time, the compressive strength and flexural strength of polypropylene fiber concrete decrease gradually. After 14 days of corrosion, the compressive strength and flexural strength of polypropylene fiber concrete in Na2SO4 and NaCl solutions are 45.3 MPa and 42.6 MPa, as well as 5.6 MPa and 4.9 MPa, respectively. ③ At 30 mm away from the surface, the SO24− concentration of concrete without fiber is 1.4%, and the Cl− concentration is 1.6%. The SO24− concentration of concrete with 3% polypropylene fiber is 1.1%, and Cl− concentration is 1.1%.
Engineering Properties and Application Proposals of African Shell Soil
ZHOU Xingye, TANG Hao, LIU Haiyan, XIAO Qian, and SHAN Lingyan
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.039
In order to find out the engineering properties of African shell soil and propose its rational use in highway construction, based on a planned highway project in Senegal, an experimental study was carried out to analyze the particle composition, physical properties, chemical properties, engineering properties, mechanical properties, and salinability of shell soil along the route. According to the method in French standards, the soil quality was classified, and the application proposal for subgrade filling was given. The results show that the shell soil is composed of coarse particles with a particle size of 1–40 mm, shell and sand mixture with a particle size of 0.5–1 mm, and sand with a particle size of less than 0.5 mm, with a mass percentage of 14%, 5%, and 81%, respectively. It has a certain engineering grading and can be classified as granular materials. Coarse-grained components and mixtures of shell and sand in shell soil are hard and have high mechanical strength, and the California bearing ratio (RCBR) is much higher than that of sand. The plastic index of sand in shell soil is only 4, and the plasticity is low; the main chemical components are quartz and a small amount of stone salt, indicating a certain saline-alkali property. The total salt content of shell soil is 0.73%, which can be judged as chlorine saline soil, and the salinization degree is medium saline soil. According to the classification method of soil quality in French standards, the shell soil in Senegal can be classified as A1ts, which can be used as the subgrade filling material of the planned highway after taking corresponding measures.
Study on Mix Design and Performance of Cement Stabilized Coral Reef Mixture
FAN Xueyong, XU Gang, and MA Qiang
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.040
The dredging process of harbor ponds will produce a large number of coral reef rocks. In order to reduce the impact of stone mining on the natural environment and improve the application of coral reef rock in the road base, this paper carried out the design of coral reef rock mixture grading according to Taylor n method, analyzed the impact of compaction process on the mixture grading through compaction test, and evaluated the degree of aggregate fragmentation with the breakage rate B5. The road performance of cement-stabilized coral reef rock mixture was studied by measuring the unconfined compressive strength, splitting strength, drying shrinkage, and temperature-induced shrinkage of the mixture. The results show that the compaction process will lead to aggregate particle breakage, and the degree of breakage is proportional to the coarse aggregate content of the mixture. The compressive strength and splitting strength of the mixture are directly proportional to the coarse particle content and cement content. In order to meet the strength requirements of the base material, the coarse particle content of the coral reef rock mixture should not be less than 50%, and the cement content should not be less than 4%. The shrinkage deformation of cement-stabilized coral reef rock mixture is obvious due to the high water loss rate in the early stage, and the shrinkage strain decreases with the increase in coarse aggregate content in the mixture. The temperature-induced shrinkage strain of the mixture is inversely proportional to the coarse aggregate content, and the temperature-induced shrinkage deformation of the mixture is larger when the temperature is 50–40 °C, so the influence of environmental temperature should be considered in the construction process.
Influence of Warm Mixture and Asphalt Type on Dynamic Modulusof Mixture
SONG Yunlian, JIANG Yu, and LIU Heng
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.041
Through dynamic modulus tests at different temperatures and loading frequencies, the dynamic mechanical properties of base asphalt and SBS-modified asphalt mixed with RH-type and Evo-type warm mix agents were studied. At the same time, the displacement factor at reference temperature was determined according to the time-temperature equivalent principle, and the master dynamic modulus curves of the warm mixed base asphalt mixture and the warm mixed SBS-modified asphalt mixture were fitted by the Sigmoial function. The results show that: ① At different temperatures and loading frequencies, the distribution of dynamic modulus and phase angle of warm mixed SBS-modified asphalt mixture is more concentrated than that of warm mixed base asphalt mixture, or in other words, the performance of warm mixed SBS-modified asphalt mixture is more stable. ② According to the master dynamic modulus curve with rutting factor at 50 °C and reference temperature at 20 °C at 0.01 Hz, the high temperature performance of the base asphalt mixture is improved after adding warm mix agents, while that of SBS-modified asphalt mixture is decreased. ③ In view of the environmental protection and mechanical properties, it is recommended to use an RH-type warm mix agent in the base asphalt mixture and Evo-type warm mix agent in the SBS-modified asphalt mixture.
Study on Preparation and PAC-13 Road Performance of High Viscosity Modified Asphalt
GUO Xiaosheng, FU Li, GUO Jiaohe, WANG Keqi, and LI Jiyan
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.042
In order to develop high-viscosity modified asphalt that meets the technical requirements of JTG/T 3350-03-2020 Technical Specifications for Design and Construction of Porous Asphalt Pavement, the influence of modifiers and stabilizers on the performance of high-viscosity modified asphalt was studied by using Sinopec Donghai asphalt as the base material through control variable method. The asphalt modification process was optimized by a uniform design test, and the road performance of the modified asphalt with high viscosity was evaluated by PAC-13 gradation. The results show that the high-viscosity modified asphalt prepared by Donghai asphalt through the wet process can fully meet the index requirements, and its dynamic viscosity at 60 °C is greater than 5 × 104 Pa·s and can be customized according to demand. Meanwhile, its Brookfield viscosity at 170 °C is low, which is conducive to uniform mixing of the mixture. The self-developed MAW-2 stabilizer can not only make the storage stability of the high-viscosity modified asphalt meet the requirements of the standard but also cooperate with the polymer modifier to improve the dynamic viscosity of the asphalt and its high temperature property. When the void ratio of the mixture is 20.3%, its Marshall stability can reach 12.7 kN, and the flyaway loss in the Cantabro test and flooding test is low at 20 °C, indicating good high temperature stability, which can effectively prevent the stone flying and other problems of the drainage asphalt pavement.
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.043
To achieve accurate determination of rubber powder content in rubber asphalt, two new methods were proposed. The first method is to calculate the content of rubber powder by measuring the content of cobalt (Co) and stibium (Sb) in matrix asphalt, rubber powder, and rubber asphalt. The second method is to calculate the content of rubber powder by weighing the residue after burning rubber asphalt and its components. The two methods were used to determine the content of rubber powder of six kinds of rubber asphalt prepared in the laboratory and four kinds of rubber asphalt sampled in the factory, and the accuracy and reliability of the two methods were verified. The results show that it is accurate to calculate the content of rubber powder according to the content of Co and Sb in rubber asphalt. The accuracy of calculating the content of rubber powder in rubber asphalt directly by using the percentage of residue after combustion is low, but the modified prediction model of rubber powder in the combustion test has high accuracy. The research results can provide a reference for the production quality control of rubber asphalt and the rapid and accurate determination of rubber powder content in practical engineering.
Study on Prediction of Shear Strength of Coarse-Grained Soil Use Parallel Gradation Method
LIU Yongwen, HU Pan, and MA Li
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.044
The shear strength of coarse-grained soil is difficult to be obtained by experiment in highway slag dumps. To address this issue, this paper used the parallel gradation method to configure the remade soil sample with small particle size and carried out direct shear tests of different sizes. The test results were compared with the shear strength parameters of the original coarse-grained soil, and the influence of the size effect was analyzed. The feasibility of using the parallel gradation method to predict the shear strength of coarse-grained soil was discussed. The results show that the direct shear test can predict the shear strength of the original coarse-grained soil better when the fine grain content of the soil sample using the parallel gradation method is small (0%–10%), and the sample preparation + test time is reduced to about 10% of the original time. When the fine grain content of the soil sample using the parallel gradation method is high (>10%), although the prediction effect of the internal friction angle is good, the cohesion deviates greatly from the original soil. When the above problem occurs, 4–5 groups of soil samples using the parallel gradation method are configured to conduct direct shear tests, and the Sigmoid function relationship curve between cohesion and fine grain content is established. By using the relationship curve to calculate the cohesion of the original soil, a better cohesion prediction effect can be achieved. This method can provide a reference for obtaining shear strength parameters of coarse-grained soil in the process of highway construction.
Study on Influence of Ultraviolet Radiation Aging on Rheological Properties of SBS-MCR Modified Asphalt
YE Xiangqian, ZOU Xiaolin, and TIAN Fafu
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.045
In order to study the effect of ultraviolet aging on the pavement performance of SBS-modified rubber powder (MCR) composite modified asphalt, an improved ultraviolet aging test chamber was used to simulate the ultraviolet radiation effect of asphalt cement in the actual road use process, and the influence of ultraviolet aging on the conventional indexes of asphalt was analyzed by conventional test methods. DSR and BBR tests were used to analyze the high temperature, low temperature, and fatigue rheological properties of asphalt samples after ultraviolet aging. The results show that with the increase in ultraviolet aging time, the penetration at 25 °C and ductility indexes at 5 °C of SBS-MCR composite modified asphalt decrease significantly; the dynamic viscosity at 60 °C increases significantly, and the softening point shows obvious two-stage aging characteristics. The rutting factor G*/sinδ of SBS-MCR composite modified asphalt is obviously increased after long-term ultraviolet aging, but the deformation recovery ability is decreased under high temperature conditions. Ultraviolet aging can increase the bending stiffness modulus S and reduce the creep recovery rate m, and the low temperature rheology of asphalt can be reduced as a whole. In addition, ultraviolet aging has an adverse effect on the fatigue rheological properties of asphalt.
Pavement Structure and Materials
Research on Comprehensive Optimization Design of Short Distance Toll Station Service Area for Suburban Road A Case Study of the Overall Plan Designof Huangcun Service Area of Guangzhou East Ring Expressway
LIAO Yonggang, DING Zhenzhong, GUO Kai, and WANG Xiaofei
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.046
Due to rapid economic development, the traffic demand has changed, and the expressway often needs to add other service functions on the basis of the original traffic service to achieve perfect traffic operation. Focusing on the Huangcun Toll Station and Huangcun Interchange of Guangzhou East Ring Highway, this paper put forward the overall scheme design of the short-distance Huangcun Service Area by using the land on both sides of the existing expressway. At the same time, through the simulation analysis of VISSIM software, the overall design scheme was verified to improve the traffic efficiency and safety between the toll station and the interchange. The research results can provide a reference for the flexible design and rational use of short-distance toll-service facilities on urban expressways.
Study on Safety Evaluation of Parallel Escape Laneson Mountain Expressways
LIU Weiwei, WAN Hang, ZHAO Yifei, ZHAO Yan, and QI Chenxu
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.047
Based on the AHP-TOPSIS method, a safety evaluation model of parallel escape lanes on mountainous expressways was established. The AHP method was used to classify and aggregate the related factors affecting the safety of parallel escape lanes, and a safety evaluation index system of target layer, criterion layer, and index layer was established. By using the “1–9 scale method” and combining expert opinions, the weights of single-layer indexes, comprehensive weights, and comprehensive weight sequences were determined. The close degree between the evaluation scheme and the positive ideal solution was calculated by the TOPSIS method, and the corresponding relationship between the close degree and the safety grade of parallel escape lanes at five levels was given. Based on the design results of three parallel escape lanes, the evaluation model was applied to evaluate its safety level, and improvement measures were proposed.
Application of BIM Technology in Highway Reconstruction and Extension Design
HUANG Yan
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.048
By analyzing the characteristics of highway reconstruction and expansion design, the organization structure of the BIM model suitable for highway reconstruction and expansion projects was proposed, and the application technical route of BIM in the design stage of highway reconstruction and expansion was summarized. In this paper, the modeling methods of the environmental model, old road engineering model, and new road engineering model were described in detail, and the application practice was carried out in many highway reconstruction and expansion projects in view of scheme demonstration and comparison, highway performance analysis, cross-sectional drawing and engineering volume statistics, auxiliary traffic organization design, etc.
Identification of Freeway Accident-Prone Sections Based on K-Means Clustering Algorithm
WU Zhimin, HUANG Jue, and XIANG Qi
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.049
In order to identify highway accident-prone sections, this paper presented a method based on the K-Means clustering algorithm to identify accident-prone sections. According to the accident severity, road production loss and average casualty compensation were introduced as the evaluation indexes of equivalent accident number, and the traditional equivalent accident number was improved. According to the statistical distribution characteristics of the improved equivalent accident number, the section length was determined, and the accident-prone section was initially identified by the cumulative frequency method. The K-Means clustering algorithm was used to cluster the initially selected accident-prone sections, and the final accident-prone sections were obtained. In order to verify the correctness of the proposed method, the accident-prone sections from Hekou to Pingtai of the Guangzhou–Wuzhou Expressway were identified. The results show that compared with the traditional equivalent accident number, the improved equivalent accident number can better reflect the accident severity. The improved equivalent accident number follows the negative binomial distribution, and the objective section length can be obtained according to its statistical distribution characteristics. The selection result of the K-Means clustering algorithm is superior to the DBSCAN algorithm, and the total length of accident-prone sections screened by the K-means clustering algorithm accounts for 66.7% of the initial results. This method can provide a strong theoretical basis for the management of accident-prone sections of expressways.
Application of BIM Technology in Expressway Reconstruction and Extension Construction Management
XIA Jianping, WANG Chao, XU Run, ZHAO Jie, and SONG Jie
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.050
In order to achieve more efficient management of expressway reconstruction and expansion projects, this paper studied the application of BIM technology in the management of expressway reconstruction and expansion projects and proposed a BIM technology-based reconstruction and expansion project management method, which has been successfully applied to the Beijing–Shanghai expressway reconstruction and expansion projects. The method mainly includes the following four aspects: intelligent site management based on a BIM collaborative management platform, standardized site construction management, oblique photography-assisted deep excavation site management, and more effective communication management based on BIM technology. Through the application exploration of this paper, BIM technology solved the problems of multiple management levels and difficult collaborative management in reconstruction and expansion projects, which could realize the reasonable arrangement of construction processes, accelerate the project progress, improve the project quality and management level, and provide a solid foundation for the future application research of BIM in the management of highway reconstruction and expansion projects.
Traffic Engineering and Management
Design Subcontract Management under FIDIC Contract Terms-Based on North-South Montenegro Highway Project
FENG Yuesen and GAO Yichen
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.051
This paper sorted out the subcontracting management in the design of the north-south expressway project in Montenegro, defined the necessary process of subcontractor selection, and provided management means for subcontractor design progress and quality control. It also analyzed some problems in the design subcontracting management and gave solutions, providing references for other projects in the surrounding area or similar projects under FIDIC contract terms.
Study on Stopping Sight Distance of Driver less Open Test Road in Xiangjiang New Distric
LU Chao, LI Zhenfa, WANG Wusheng, and HU Shengkui
Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.052
The General Office of the National Development and Reform Commission (2020) Document No. 202 Intelligent Vehicle Innovation & Development Strategy plans the gradual development and application of driverless supporting technologies in some cities and expressways, but it has not yet issued specifications and documents on the technical standards for driverless roads. With the rapid development of driverless technology, it is necessary to study the technical indicators of related open test roads and dedicated roads, especially the indicator of human, vehicle, road, and environmental safety, namely parking sight distance. In this paper, a new formula for calculating parking sight distance was proposed by combining the traditional formula for parking sight distance and the principle of driverless braking, so as to provide theoretical guidance for future research on parking sight distance on driverless roads. road engineering, driverless technology, parking sight distance, calculation formula
