Volume 43, Issue 1 (2023)
Article
Experimental study on the diagonal shear of asphalt mixture at micro‐surfaces
HUANG Weirong, YANG Yuzhu, WANG Cheng, HUANG Feng, and YANG Bo
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.031
A new 45° diagonal shear test was conducted to study the shear properties of the SBR-modified emulsified asphalt mixture at the micro-surface under the influence of different loading rates, different interface states, and different temperatures and water. The shear failure forms at the micro-surface at different temperatures were explained, and the effects of viscous layer oil, soil, and water on the shear strength at the micro-surface were analyzed. The results show that a faster loading rate at the micro-surface indicates higher shear strength. The shear failure mode of micro-surface at normal temperature is mainly an interlayer shear failure, while that at high temperature is a self-shear failure. When the surface of the original pavement is rough, the spread of viscous layer oil has little contribution to the increase in interlayer shear strength, and the mud water will reduce the interlayer shear strength at the micro-surface. Water immersion will damage the interlayer shear strength at the micro-surface, and spraying viscous layer oil can effectively improve the water damage resistance of the interface between the micro-surface and the original pavement.
Study on thermal property of fast growing grass fiber and its asphalt mortar
XIA Chaoming, JIANG Kang, WU Chaofan, and LIU Kefei
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.032
In order to investigate the thermal properties of fast-growing grass fiber and its asphalt mortar, the physical properties and thermal properties of bamboo fiber, reed fiber, and its asphalt mortar were tested and compared with those of lignin fiber and its asphalt mortar by physical property test, thermal weight loss test, and differential scanning calorimetry test. The results show that the addition of plant fiber can effectively improve the high temperature performance of asphalt, but it has a slight inhibition effect on the low temperature performance of asphalt. The quality loss of plant fiber in different temperature ranges is the same. Among the three plant fibers, lignin fiber has the best thermal stability, followed by bamboo fiber and reed fiber. Plant fiber can effectively improve the thermal melting property of asphalt mortar, improve the thermal stability of asphalt mortar, and reduce the temperature sensitivity. Asphalt mortar of bamboo fiber has the best low temperature cracking resistance and temperature sensitivity, and the low temperature stability of fast-growing grass fiber is better than that of lignin fiber.
Uniaxial shear test and mesoscopic numerical simulation of cemental soil based on PFC2D method
YANG Zhihui and LI Shanhua
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.033
Uniaxial compression tests were carried out on stable soft soil samples with different cement contents. Based on the test results, a mesoscopic numerical simulation of PFC2D discrete element particle flow during soil sample deformation was conducted to analyze the mechanical behavior and displacement field distribution of cement soil after failure. The results show that with the increase in cement content, the uniaxial shear strength and elastic modulus of the solidified soft soil sample show an exponential function and rise, and the failure strain shows a quadratic function with the increase in cement content. The mechanical parameters and stress-strain curves of cement soil samples obtained by PFC2D discrete element particle flow simulation are close to the test results, and the discrete element simulation results show that the cement content has a significant effect on the mechanical properties of soil. With the increase in cement content, the failure mode of solidified soft soil gradually changes from crushing failure to shear failure. The displacement vector field obtained by discrete element simulation accurately reflects the failure mode characteristics of cement-solidified soft soil under uniaxial compression load.
Study on effect of fiber stabilizers on water temperature cycle damage resistance of drainage asphalt mixtures
LIU Fuming, WU Di, HE Qingde, and YANG Zhiping
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.034
In order to study the effect of fiber stabilizer on the water temperature cycle damage resistance of drainage asphalt mixture, drainage asphalt mixture without fiber stabilizer and with wood fiber, polyester fiber, and basalt fiber, respectively, were compared through tests. By standard dispersion test and immersed dispersion test, the anti-spalling ability of the mixture was analyzed. Under the same asphalt condition, the standard dispersion loss of the drainage asphalt mixture was reduced to different degrees after adding fiber stabilizer, which could increase the anti-spalling property of the drainage asphalt mixture to some extent. The splitting, indirect tensile, and rutting tests were carried out on samples with and without water temperature cycle damage to analyze the water temperature cycle damage resistance of the mixture. The splitting strength of the drainage asphalt mixture increased after adding fiber stabilizer. The indirect tensile test finds that the stiffness modulus of the drainage asphalt mixture is increased after adding fiber stabilizer, and the low-temperature cracking resistance of the asphalt mixture with basalt fiber is the best, followed by wood fiber. The rutting test shows that the addition of basalt fiber stabilizer has the most obvious improvement on the dynamic stability of the drainage asphalt mixture. The results show that the addition of polyester fiber and basalt fiber can obviously improve the influence of the water immersion environment on the spalling of the drainage asphalt mixture, and basalt fiber can obviously improve the water temperature cycle damage resistance, low temperature cracking resistance, and high-temperature stability of the mixture.
Experimental analysis on recycling and mechanical properties of waste cement
CHEN Liang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.035
In order to recycle waste cement, construction waste cement materials were collected in the laboratory, and they were crushed, ground, and heat treated to facilitate reuse. Then, the waste cement was combined with the commonly used active fly ash admixture to prepare a new cement material for test analysis. The results show that the new cement material produced by industrial by-product, fly ash and waste cement material is feasible. A small amount of construction waste cement material (about 5%) can increase the 28-day compressive strength of cement by more than 50%, and the compressive strength of the prepared building material can reach about 90 MPa.
Experimental study on characteristics and stability of different aged steel slag aggregate
ZHANG Hongri, WANG Guiyao, FENG Jian, LAN Tianzhu, and WU Tao
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.036
Steel slag aggregate has good building material properties, but the utilization rate of steel slag in road engineering is low at present. In this paper, the chemical composition, basic physical and mechanical indexes, f⁃CaO, f⁃MgO, pulverization rate, CRB expansion rate, and other indexes of open-air aged steel slag aggregate in Fangchenggang, Guangxi Province for 0, 6, and 12 months were studied. The results show that the physical and mechanical properties of steel slag aggregate basically meet the requirements of road base materials and subgrade fillers, but the indexes of f⁃CaO, pulverization rate, and CRB expansion rate of steel slag aggregate aged 0 and 6 months fail to meet the requirements of road base and backfill materials. The steel slag aggregate aged 12 months is slightly less than the standard limit. It can be seen that the steel slag aggregate used for road base and backfill materials must be aged in the open air for at least 12 months to meet the road stability requirements.
Influence factors of deicing and thaw performance of asphalt mixture with low freezing point
ZHOU Shuiwen, LIN Fang, ZHANG Xiaohua, ZHANG Lingbo, and JIANG Haoqiu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.037
The conductivity test was used to study the release law of thawing and deicing components. The freezing test was used to study the cooling law of the mixture, and the thawing rate test was used to study the thawing and deicing performance. The results show that the release of thawing and deicing components of materials with a low freezing point is temperature-dependent, and the release at the high temperature is 3.49–3.77 times that at the low temperature. The granular materials tend to dissolve in water, which results in the release rate of thawing and deicing components faster than that of the filler materials. The freezing process is divided into three stages. The freezing point and duration of the freezing stage are affected by the type and amount of material, as well as the water content, and the freezing point of ZG-10S is the lowest. Increasing the dosage and decreasing the water content are equivalent to increasing the concentration of the solution, which can effectively reduce the freezing point. The melting time has the greatest and most significant influence on the thawing and deicing performance, followed by temperature because the temperature dependence of the release rate determines the limited effect of thawing and deicing.
Study on pavement performance of waterborne epoxy emulsified asphalt and its application in micro‐surface
JIANG Hai and LIU Dachang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.038
In order to improve the pavement performance at micro-surface, waterborne epoxy resin was used to modify the emulsified asphalt, and the compatibility, microstructure, mechanical properties, rheological properties, and pavement performance of mixtures of the modified emulsified asphalt were studied. The storage stability test shows that the epoxy emulsion has good compatibility with emulsified asphalt. With the increase in waterborne epoxy resin content, the modified emulsified asphalt tends to form an epoxy resin-dominated skeleton structure. At the same time, with the increase in waterborne epoxy resin content, the adhesion and mechanical properties of emulsified asphalt and aggregate are significantly improved. At 20% content, the bonding strength is increased by more than two times, and the shear strength is increased by more than one time. Rheological tests show that the waterborne epoxy resin can improve the rutting resistance and elastic recovery rate of emulsified asphalt, and the high temperature performance is significantly improved. The research on the performance of the mixture at the micro-surface shows that the waterborne epoxy resin can significantly improve the water stability and rutting resistance of the emulsified asphalt, and the water stability and rutting resistance of the mixture tend to be stable when the content reaches 20%. In summary, for the modified emulsified asphalt system in this paper, it is recommended that the content of waterborne epoxy resin should be 10%–20%.
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.039
In order to improve the crack resistance of recycled asphalt mixture, a new styrenic block copolymer (SBS)/rubber composite modified asphalt with excellent crack resistance was proposed for the regeneration of reclaimed asphalt pavement (RAP). Based on the creep of low temperature bending beam, confined temperature stress, and four-point bending fatigue test, the low temperature cracking resistance and fatigue cracking performance of composite modified asphalt and SBS-modified asphalt were studied. The results show that the addition of rubber can improve the low temperature and medium temperature crack resistance of recycled asphalt concrete, which may be related to the propagation of micro-cracks formed in the initial cracking of the mixture into the polymer network to absorb the fracture energy and inhibit the further development of micro-cracks. Further analysis of the fracture temperature shows that the composite modified asphalt mixture can extend the service temperature range of the pavement by about 6 °C than the ordinary SBS-modified asphalt mixture, which is conducive to the promotion and application of recycled asphalt mixture in the cold area of northwest China.
Study on anti‐scattering performance of asphalt concrete on aggregate scattering pavement of highway
YANG Siyuan and CHEN Guiliang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.040
Due to the lack of quantitative evaluation methods for aggregate scattering degree of expressway asphalt pavement in China and abroad, according to the disease characteristics of surface layer spalling, this paper adopted the Cantabro standard dispersion test to sample the concrete of the section with aggregate scattering of Huangqunan Expressway (G3) in Zhejiang Province. The dispersion impact damage modes of the mixture with different severity were analyzed, and the anti-dispersion performance of concrete was evaluated by mass loss rate and water absorption rate. The results show that aggregate scattering will reduce the density of the concrete structure at the surface layer, and the anti-dispersion performance of the damaged section is lower than that of the normal road surface. A more serious appearance scattering degree means a higher water absorption rate, lower anti-dispersion performance of the concrete and more broken specimens generated by the dispersion impact. Finally, based on the test results, the relevant suggestions for the treatment of aggregate scattering are put forward.
Study on the effect of quicklime on the properties of cold mix asphalt
LIU Tao, YI Ming, and SONG Tao
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.041
The low initial strength of cold mixed asphalt mixture leads to the delay of traffic opening time, and the large void ratio leads to poor water stability and other problems, which seriously hinder the development of cold mixed environment-friendly construction mode. In this paper, based on the principle that the heat of quicklime in the presence of water promotes the rapid loss of water in the cold mixed mixture, the mixing test and cohesion test of the MS-3 slurry cold mixed asphalt mixture with quicklime were carried out to explore the influence of quicklime on the demulsification time and cohesion. Then, the effect of quicklime on the initial strength and water stability of the cold mixed mixture was verified by testing the void ratio and uniaxial penetration strength of the AC-13 cold mixed asphalt mixture. The test results show that the process of demulsification of the cold mixed mixture is accelerated by the reaction of quicklime with water and the formation of alkaline calcium hydroxide, and the formation of early strength can greatly shorten the time of traffic opening. At the same time, the composite gelling structure has a significant effect on improving the overall strength and water stability of the pavement.
Specially Invited Articles
The calculation theory of humidity for subgrade ：A perspective review
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.001
Subgrade humidity has a significant impact on its stiffness, deformation, and other properties. The theoretical calculation method of humidity field has always been one of the key issues in road engineering as a research method to evaluate its evolution law and mechanism. This paper reviewed and summarized the control equation of subgrade humidity calculation, hydraulic characteristics of unsaturated subgrade soil, and influencing factors of humidity. It was found that there were few studies on the coupling effects of multiple fields and factors such as stress, seepage, vegetation, and atmosphere in the whole calculation method system. It is suggested to carry out such studies to accurately evaluate the subgrade humidity and the long-life design and practice of supporting road engineering.
The calculation theory of humidity for subgrade ：A perspective review
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.001
Subgrade humidity has a significant impact on its stiffness, deformation, and other properties. The theoretical calculation method of humidity field has always been one of the key issues in road engineering as a research method to evaluate its evolution law and mechanism. This paper reviewed and summarized the control equation of subgrade humidity calculation, hydraulic characteristics of unsaturated subgrade soil, and influencing factors of humidity. It was found that there were few studies on the coupling effects of multiple fields and factors such as stress, seepage, vegetation, and atmosphere in the whole calculation method system. It is suggested to carry out such studies to accurately evaluate the subgrade humidity and the long-life design and practice of supporting road engineering.
Subgrade Engineering
Field experiment on deep response of slope subjected to different rainfalls in Plateau mountainous area of Northwest Yunnan
CHEN He, LU Zhiqiang, LI Guo, and CHEN Zhengyu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.002
In order to investigate the characteristics and mechanism of deep response of slopes subjected to different rainfalls in plateau mountainous area of Northwest Yunnan, remote real-time monitoring devices were deployed to carry out slope prototype field tests, analyze the effects of natural rainfalls in different forms and intensities on deep displacement and groundwater level changes, and put forward suggestions for landslide monitoring and early warning. The results show that the characteristics of heavy rainfall, steep slope, and rock fragmentation during flood season can induce the frequent fluctuation of groundwater level in the deeper part of the slope, which results in the formation of two layers of deformation shear zone in the deep part of the slope. The shallow displacement increases with the increase in cumulative rainfall, and the cumulative rainfall required by continuous rainfall to induce shallow displacement is smaller than that by intermittent rainfall. The long-term continuous fluctuation of groundwater level is the main reason for the intermittent sharp increase in deep displacement. Monitoring indexes should be selected from the perspective of early warning, and more attention should be paid to the sequence of rainfall, groundwater level, and displacement used for landslide early warning.
Experimental study on shear strength of EHP piles
WANG Nanjiang, LIU Jianlong, QIU Chengchun, ZHANG Yuting, and TAO Xiaoyu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.003
The new environmental homogeneous plastic (EHP) pile improves the construction technology of traditional soil-cement mixing piles. It mixes the soil-cement slurry evenly in advance and then pours it into holes, so as to form piles with controllable physical properties. In order to test the strength of EHP piles, direct shear tests were carried out on field core sampling, field stirring sampling, and laboratory sampling, and the effects of pile depth, cement content, age, and curing conditions on shear strength were discussed. The test results show that the shear stress-displacement curve of the in-situ core sample is strain-softening; the shear strength distributes uniformly along the depth of the pile and increases with the increase in vertical pressure; the cohesion fluctuates based on a certain value, and the internal friction angle is little affected by the cement content. The shear strength of the standard curing samples in the laboratory tends to be stable at 14 days of age, with high early strength, and the mixing uniformity and curing conditions have a great influence on the shear strength. The shear strength of the in-situ core sample is lower than that of the standard curing sample in the laboratory, and the total mean shear strength reduction coefficient decreases with the increase in cement content, or in other words, the strength difference between the two increases.
Analysis on influence factors of swelling deformation of gravel pile in soft soil area based on orthogonal numerical test
FAN Liujun, LU Xiaoming, and MIAO Peng
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.004
The gravel pile composite foundation is usually accompanied by swelling deformation when vertical settlement deformation occurs. The research on the swelling deformation characteristics and influencing factors of gravel pile composite foundations is of great importance for analyzing the settlement rule and deformation mechanism of gravel pile composite foundations. Based on an orthogonal numerical test, this paper used the finite element software Midas GTS to analyze the main influencing factors of the swelling deformation of the gravel pile and used range and variance analysis to analyze the sensitivity and significance of each influencing factor. Finally, through regression analysis, the optimized swelling deformation formula was obtained. The results show that the elastic modulus of soft soil, as well as the cohesion and displacement rate of gravel pile, has significant effects on the maximum swelling strain. The cohesion and displacement rate of soft soil have a significant influence on the maximum swelling depth. The elastic modulus and displacement rate of soft soil have a significant influence on the swelling deformation length. The mechanical parameters of gravel piles have little influence on the swelling deformation characteristics. The single factor analysis shows that when the elastic modulus of soft soil is small, increasing the elastic modulus can effectively reduce the maximum swelling strain and swelling deformation length. The increase in cohesion of soft soil can reduce the maximum swelling strain, and the maximum swelling position moves down to a certain extent, or in other words, the failure point of the gravel pile moves down.
Study on ultimate bearing capacity characteristics of overlying shell foundation
BIAN Guirong, LI Fuyou, QIAN Xiaotong, and XIE Ke
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.005
For the calculation of the ultimate bearing capacity of the overlying hard crust foundation, based on the theory of Meerhoff and Hanna’s impact and shear failure, the sealing effect and stress diffusion effect of the overlying hard crust foundation were considered, and the formula for calculating the ultimate bearing capacity of the overlying hard crust double-layer foundation was derived and verified by an actual engineering example. The maximum error between the measured value and the calculated value of Hansen’s weighted average method, diffusion angle method, and Meerhoff and Hanna’s method was 74.2%, 31.5%, and 15.2% respectively, while the error was less than 6% by using the improved algorithm. It shows that it is necessary to consider the sealing effect and stress diffusion effect of the overlying hard crust foundation when calculating the ultimate bearing capacity of the foundation. At the same time, this method can be used as a reference for calculating the ultimate bearing capacity of the overlying hard crust foundation.
Field experiment on deep response of slope subjected to different rainfalls in Plateau mountainous area of Northwest Yunnan
CHEN He, LU Zhiqiang, LI Guo, and CHEN Zhengyu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.002
In order to investigate the characteristics and mechanism of deep response of slopes subjected to different rainfalls in plateau mountainous area of Northwest Yunnan, remote real-time monitoring devices were deployed to carry out slope prototype field tests, analyze the effects of natural rainfalls in different forms and intensities on deep displacement and groundwater level changes, and put forward suggestions for landslide monitoring and early warning. The results show that the characteristics of heavy rainfall, steep slope, and rock fragmentation during flood season can induce the frequent fluctuation of groundwater level in the deeper part of the slope, which results in the formation of two layers of deformation shear zone in the deep part of the slope. The shallow displacement increases with the increase in cumulative rainfall, and the cumulative rainfall required by continuous rainfall to induce shallow displacement is smaller than that by intermittent rainfall. The long-term continuous fluctuation of groundwater level is the main reason for the intermittent sharp increase in deep displacement. Monitoring indexes should be selected from the perspective of early warning, and more attention should be paid to the sequence of rainfall, groundwater level, and displacement used for landslide early warning.
Experimental study on shear strength of EHP piles
WANG Nanjiang, LIU Jianlong, QIU Chengchun, ZHANG Yuting, and TAO Xiaoyu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.003
The new environmental homogeneous plastic (EHP) pile improves the construction technology of traditional soil-cement mixing piles. It mixes the soil-cement slurry evenly in advance and then pours it into holes, so as to form piles with controllable physical properties. In order to test the strength of EHP piles, direct shear tests were carried out on field core sampling, field stirring sampling, and laboratory sampling, and the effects of pile depth, cement content, age, and curing conditions on shear strength were discussed. The test results show that the shear stress-displacement curve of the in-situ core sample is strain-softening; the shear strength distributes uniformly along the depth of the pile and increases with the increase in vertical pressure; the cohesion fluctuates based on a certain value, and the internal friction angle is little affected by the cement content. The shear strength of the standard curing samples in the laboratory tends to be stable at 14 days of age, with high early strength, and the mixing uniformity and curing conditions have a great influence on the shear strength. The shear strength of the in-situ core sample is lower than that of the standard curing sample in the laboratory, and the total mean shear strength reduction coefficient decreases with the increase in cement content, or in other words, the strength difference between the two increases.
Analysis on influence factors of swelling deformation of gravel pile in soft soil area based on orthogonal numerical test
FAN Liujun, LU Xiaoming, and MIAO Peng
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.004
The gravel pile composite foundation is usually accompanied by swelling deformation when vertical settlement deformation occurs. The research on the swelling deformation characteristics and influencing factors of gravel pile composite foundations is of great importance for analyzing the settlement rule and deformation mechanism of gravel pile composite foundations. Based on an orthogonal numerical test, this paper used the finite element software Midas GTS to analyze the main influencing factors of the swelling deformation of the gravel pile and used range and variance analysis to analyze the sensitivity and significance of each influencing factor. Finally, through regression analysis, the optimized swelling deformation formula was obtained. The results show that the elastic modulus of soft soil, as well as the cohesion and displacement rate of gravel pile, has significant effects on the maximum swelling strain. The cohesion and displacement rate of soft soil have a significant influence on the maximum swelling depth. The elastic modulus and displacement rate of soft soil have a significant influence on the swelling deformation length. The mechanical parameters of gravel piles have little influence on the swelling deformation characteristics. The single factor analysis shows that when the elastic modulus of soft soil is small, increasing the elastic modulus can effectively reduce the maximum swelling strain and swelling deformation length. The increase in cohesion of soft soil can reduce the maximum swelling strain, and the maximum swelling position moves down to a certain extent, or in other words, the failure point of the gravel pile moves down.
Study on ultimate bearing capacity characteristics of overlying shell foundation
BIAN Guirong, LI Fuyou, QIAN Xiaotong, and XIE Ke
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.005
For the calculation of the ultimate bearing capacity of the overlying hard crust foundation, based on the theory of Meerhoff and Hanna’s impact and shear failure, the sealing effect and stress diffusion effect of the overlying hard crust foundation were considered, and the formula for calculating the ultimate bearing capacity of the overlying hard crust double-layer foundation was derived and verified by an actual engineering example. The maximum error between the measured value and the calculated value of Hansen’s weighted average method, diffusion angle method, and Meerhoff and Hanna’s method was 74.2%, 31.5%, and 15.2% respectively, while the error was less than 6% by using the improved algorithm. It shows that it is necessary to consider the sealing effect and stress diffusion effect of the overlying hard crust foundation when calculating the ultimate bearing capacity of the foundation. At the same time, this method can be used as a reference for calculating the ultimate bearing capacity of the overlying hard crust foundation.
Pavement Engineering
Review and outlook for long‐life asphalt pavement
XU Xizhong, WEI Jincheng, YAN Xiangpeng, and ZHANG Zhengchao
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.006
In order to make clear the research status of long-life asphalt pavement in China and abroad, this paper summarized the development characteristics, pavement structure, design index, pavement material, dynamic response analysis of pavement, fatigue performance estimation, and other hot issues of long-life asphalt pavement, compared the structural characteristics of long-life asphalt pavement in various countries, and summarized the results of pavement material design and optimization. The research progress of the dynamic response of asphalt pavement was summarized, and the development direction of long-life asphalt pavement was discussed. The comprehensive analysis shows that long-life asphalt pavement is the development trend of asphalt pavement in the future. At present, there are still some shortcomings in the research on long-life asphalt pavement, such as the lack of a unified design index, poor accuracy of mechanical response prediction model, and weak pertinence of structure and material design. Further research is needed from the aspects of solid engineering analysis and verification, mechanical response prediction model modification, structure and material multi-scale genomic analysis, etc.
Application of digital image processing in cracks of concrete pavement
GAO Fan, HE Chunguang, WANG Pengzhang, QIN Yanping, and DUO Huaqiong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.007
The image obtained by using the traditional crack detection method of concrete pavement has some problems, such as low contrast and high noise, which makes it difficult to meet the requirements of modern road engineering management or non-destructive testing. In order to eliminate the interference in crack images, digital image processing technology was used to improve the image quality through computers. This paper took digital image processing as the core and introduced its development and application in pavement cracks. Based on the research progress and achievements of digital image processing on pavement cracks in recent years, the principles and characteristics of digital image processing in removing noise in crack images, augmentation, segmentation, and feature extraction were analyzed. Finally, the existing problems were summarized, and the future development trends and application prospects were discussed. Digital image processing technology can effectively improve the quality of pavement crack images and enhance the important characteristics, which is of great application value in concrete pavement crack image processing.
Study on modulus characteristics of semi‐flexible pavement
CAI Yubin, GONG Minghui, XIONG Zijia, DENG Cheng, PENG Gang, ZHANG Lihua, and HONG Jinxiang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.008
Semi-flexible pavement has the advantages of good bearing capacity and strong shear deformation resistance and is an effective means to solve the rutting disease of intersections, bus stops, and other sections. However, due to the difference in mechanical properties, semi-flexible pavement can not completely refer to the design method of cement concrete pavement or asphalt concrete pavement, and one of the important tasks of establishing a design system suitable for semi-flexible pavement is to analyze the material modulus characteristics of pavement. In this paper, the dynamic modulus, indirect tensile stiffness modulus, and rebound modulus of laboratory forming and coring specimens were tested based on laboratory tests, and the pavement deflection data was collected by drop hammer bending meter. The test results show that the dynamic modulus of semi-flexible pavement material and asphalt mixture is similar in the range of medium temperature. Under high temperature and low frequency conditions, the dynamic modulus of the two materials is significantly different. By comparing rebound modulus and deflection data, it is found that the modulus of semi-flexible pavement is about twice that of asphalt pavement, while the bending of the former is only 1/2 that of the latter. The results show that the influence of the test method and loading mode on the modulus of the two materials is significantly different, and the pavement design should further select the modulus parameters under different test conditions according to the two typical failure modes of the pavement.
Analysis on pavement early damage characteristics and influence factors of Baiyin section of national highway 109
SHI Fuzhou, HAN Fei, TANG Dandan, LIU Wuwen, and ZHANG Jinyuan
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.009
In order to explore the cause of early damage of highway asphalt pavement in Baiyin area of Gansu Province, this paper analyzed the main factors that affected the performance of asphalt pavement and investigated the use of asphalt pavement in this area, climate environment, and traffic conditions. By taking Baiyin section of National Highway 109 as an example, the specific data were deeply analyzed. Based on the investigation of pavement use, the situation and decay rule of local asphalt pavement were summarized. According to the investigation of the climate environment, the influence of solar radiation, temperature difference, and other conditions on the performance of local asphalt pavement was analyzed. Based on the investigation of traffic conditions, the influence of the proportion of oversized trucks and traffic load grade on the performance of local asphalt pavement was clarified. The results show that the natural climate environment, traffic load grade, the thickness of pavement surfaces, and the rationality of maintenance method are the main reasons that affect the early damage of the pavement.
Analysis and evaluation of application effect of hot mix plan regeneration technology in asphalt pavement
YANG Yanhai, CUI Hong, YANG Ye, and QIAN Baitong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.010
In order to evaluate the practical application effect of plant-mixing hot regeneration technology, this paper, based on the actual project of plant-mixing hot regeneration technology in Liaoning Province, analyzed the use status, technical performance, and construction technology of pavement materials made by plant-mixing hot regeneration technology via measuring the volume index, asphalt content, grading composition, and strength of pavement core samples. The results show that the strength characteristics, high temperature stability, and low temperature crack resistance of the pavement materials made by plant-mixing hot regeneration technology can meet the normal use requirements of asphalt pavement under moderate traffic volume. The overall performance attenuation of pavement made by plant-mixing hot regeneration technology is faster than that of ordinary hot mixed asphalt pavement, and minor or intermediate repair is needed after 5–6 years of pavement regeneration. Therefore, under the condition of moderate traffic volume, the plant-mixing hot regeneration technology has a good practical application effect and is an effective method to realize the sustainable development of asphalt pavement repair and maintenance.
Review and outlook for long‐life asphalt pavement
XU Xizhong, WEI Jincheng, YAN Xiangpeng, and ZHANG Zhengchao
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.006
In order to make clear the research status of long-life asphalt pavement in China and abroad, this paper summarized the development characteristics, pavement structure, design index, pavement material, dynamic response analysis of pavement, fatigue performance estimation, and other hot issues of long-life asphalt pavement, compared the structural characteristics of long-life asphalt pavement in various countries, and summarized the results of pavement material design and optimization. The research progress of the dynamic response of asphalt pavement was summarized, and the development direction of long-life asphalt pavement was discussed. The comprehensive analysis shows that long-life asphalt pavement is the development trend of asphalt pavement in the future. At present, there are still some shortcomings in the research on long-life asphalt pavement, such as the lack of a unified design index, poor accuracy of mechanical response prediction model, and weak pertinence of structure and material design. Further research is needed from the aspects of solid engineering analysis and verification, mechanical response prediction model modification, structure and material multi-scale genomic analysis, etc.
Application of digital image processing in cracks of concrete pavement
GAO Fan, HE Chunguang, WANG Pengzhang, QIN Yanping, and DUO Huaqiong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.007
The image obtained by using the traditional crack detection method of concrete pavement has some problems, such as low contrast and high noise, which makes it difficult to meet the requirements of modern road engineering management or non-destructive testing. In order to eliminate the interference in crack images, digital image processing technology was used to improve the image quality through computers. This paper took digital image processing as the core and introduced its development and application in pavement cracks. Based on the research progress and achievements of digital image processing on pavement cracks in recent years, the principles and characteristics of digital image processing in removing noise in crack images, augmentation, segmentation, and feature extraction were analyzed. Finally, the existing problems were summarized, and the future development trends and application prospects were discussed. Digital image processing technology can effectively improve the quality of pavement crack images and enhance the important characteristics, which is of great application value in concrete pavement crack image processing.
Study on modulus characteristics of semi‐flexible pavement
CAI Yubin, GONG Minghui, XIONG Zijia, DENG Cheng, PENG Gang, ZHANG Lihua, and HONG Jinxiang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.008
Semi-flexible pavement has the advantages of good bearing capacity and strong shear deformation resistance and is an effective means to solve the rutting disease of intersections, bus stops, and other sections. However, due to the difference in mechanical properties, semi-flexible pavement can not completely refer to the design method of cement concrete pavement or asphalt concrete pavement, and one of the important tasks of establishing a design system suitable for semi-flexible pavement is to analyze the material modulus characteristics of pavement. In this paper, the dynamic modulus, indirect tensile stiffness modulus, and rebound modulus of laboratory forming and coring specimens were tested based on laboratory tests, and the pavement deflection data was collected by drop hammer bending meter. The test results show that the dynamic modulus of semi-flexible pavement material and asphalt mixture is similar in the range of medium temperature. Under high temperature and low frequency conditions, the dynamic modulus of the two materials is significantly different. By comparing rebound modulus and deflection data, it is found that the modulus of semi-flexible pavement is about twice that of asphalt pavement, while the bending of the former is only 1/2 that of the latter. The results show that the influence of the test method and loading mode on the modulus of the two materials is significantly different, and the pavement design should further select the modulus parameters under different test conditions according to the two typical failure modes of the pavement.
Analysis on pavement early damage characteristics and influence factors of Baiyin section of national highway 109
SHI Fuzhou, HAN Fei, TANG Dandan, LIU Wuwen, and ZHANG Jinyuan
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.009
In order to explore the cause of early damage of highway asphalt pavement in Baiyin area of Gansu Province, this paper analyzed the main factors that affected the performance of asphalt pavement and investigated the use of asphalt pavement in this area, climate environment, and traffic conditions. By taking Baiyin section of National Highway 109 as an example, the specific data were deeply analyzed. Based on the investigation of pavement use, the situation and decay rule of local asphalt pavement were summarized. According to the investigation of the climate environment, the influence of solar radiation, temperature difference, and other conditions on the performance of local asphalt pavement was analyzed. Based on the investigation of traffic conditions, the influence of the proportion of oversized trucks and traffic load grade on the performance of local asphalt pavement was clarified. The results show that the natural climate environment, traffic load grade, the thickness of pavement surfaces, and the rationality of maintenance method are the main reasons that affect the early damage of the pavement.
Analysis and evaluation of application effect of hot mix plan regeneration technology in asphalt pavement
YANG Yanhai, CUI Hong, YANG Ye, and QIAN Baitong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.010
In order to evaluate the practical application effect of plant-mixing hot regeneration technology, this paper, based on the actual project of plant-mixing hot regeneration technology in Liaoning Province, analyzed the use status, technical performance, and construction technology of pavement materials made by plant-mixing hot regeneration technology via measuring the volume index, asphalt content, grading composition, and strength of pavement core samples. The results show that the strength characteristics, high temperature stability, and low temperature crack resistance of the pavement materials made by plant-mixing hot regeneration technology can meet the normal use requirements of asphalt pavement under moderate traffic volume. The overall performance attenuation of pavement made by plant-mixing hot regeneration technology is faster than that of ordinary hot mixed asphalt pavement, and minor or intermediate repair is needed after 5–6 years of pavement regeneration. Therefore, under the condition of moderate traffic volume, the plant-mixing hot regeneration technology has a good practical application effect and is an effective method to realize the sustainable development of asphalt pavement repair and maintenance.
Bridge Engineering & Tunnel Engineering
Test and finite element analysis on flexural properties of steel plate‒UHPC composite beam
HUANG Yun, ZHAO Hua, and TU Lei
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.011
In order to study the flexural properties of steel plate-ultra-high performance concrete (UHPC) composite beams, the static test of the flexural properties of a steel sheet-UHPC composite beam was first carried out. Then, Abaqus finite element software was used to simulate the whole process of static loading of the specimen, and different ways were used to simulate the studs in the composite beam. The most appropriate model was thus selected. Finally, based on the calibrated finite element model, the parameters of the steel plate-UHPC composite beam were analyzed, the main parameters included: UHPC compressive strength, steel plate strength, and stud spacing and layout. The results show that in the finite element simulation analysis, the surface-surface contact finite element model is used, and the simulation analysis results are in good agreement with the measured values, which can better reflect the change law of deflection, strain, and slip in the steel plate-UHPC composite beam and be used as a reference for the subsequent finite element simulation analysis of steel plate-UHPC composite beams. The influence of each parameter on the ultimate bearing capacity of steel plate-UHPC composite beam in descending order is as follows: steel plate strength >UHPC compressive strength > stud spacing. In the structural design, it is necessary to pay attention to the selection and arrangement of studs in the shear section, while the studs in the pure section can be relatively weakened.
Study on reliability of special shaped arch bridge with spatial three‐cable‐plane inclined suspenders under live load
ZHU Liming, SHEN Kun, and WANG Xingyun
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.012
Because the structure of a special shaped arch bridge is complicated, there are few studies on the fatigue reliability of its suspender. In order to study the fatigue reliability of the suspender of complex shaped arch bridges under live load, the actual project of a 157 m through-type steel arch bridge with three-cable-plane inclined suspenders with special shaped tie bars was studied. The fatigue reliability formula based on Weibull distribution was applied to analyze the fatigue reliability of the suspender under different live load conditions. The results show that the design live load ensures a higher safety reserve and meets the allowable stress requirements of the code, but the live load stress amplitude of some short suspenders in the midspan is large, and the fatigue reliability index is close to the critical value. Therefore, the target value given in the code can be appropriately adjusted. During construction and operation, special attention should be paid to the stress of the short suspender to ensure the safety of the structure.
Research on bridge technical condition evaluation system based on BIM
XIA Zili, JING Qiang, GAO Wenbo, HUANG Liguan, and WU Xiaodong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.013
There are some practical difficulties in bridge technical condition assessment, such as low visualization degree, strong subjectivity of assessment, low efficiency of disease location, and poor continuity of assessment data. In view of the requirements of bridge technical condition assessment and the above-mentioned problems, this paper reviewed the standard system of bridge technical condition assessment in China and the application of BIM in bridge operation and maintenance, analyzed the modelling points and assessment business processes of bridge BIM model, and designed the overall framework and business module functions of the BIM-based technical condition assessment system. The bridge technical condition assessment system was developed based on the Qingzhou Bridge of Hong Kong-Zhuhai-Macao Bridge project and was initially applied to the bridge technical condition assessment, so as to improve the visualization level and efficiency of on-site operations, standardize the storage of bridge assessment data, and achieve long-term tracking of bridge service performance.
Study on pavement structure performance based on polymer alloy material for steel deck pavement
YANG Bo, HE Zhaoyi, LIU Pan, LI Kai, SHENG Xingyue, and LI Lu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.014
Based on the characteristics of light weight and high strength of polymer alloy materials, three new steel bridge deck pavement structures based on polymer alloy materials were proposed in this paper. Their high temperature performance, interface bonding performance, fatigue resistance, and skid resistance were investigated, and the performance performance was compared with that of traditional pavement structures. The test results show that the thickness of the pavement layer has a greater influence on the high temperature performance of “polymer alloy material + high-elasticity modified asphalt concrete SMA10” but has less influence on the high temperature performance of “polymer alloy material + high-toughness epoxy asphalt concrete EA10” and “poured asphalt concrete GA10 + polymer alloy material”. The polymer alloy pavement structure has good high temperature performance, interface bonding performance, and fatigue resistance, and the overall performance is similar to that of cast asphalt concrete and epoxy asphalt concrete pavement structures, which can fully meet the requirements of steel bridge deck pavement for material and structure and reduce the dead weight of the pavement layer, so as to achieve lightweight and high-strength pavement of steel bridge decks.
Comparative study on steel bridge maintenance and technical specifications of China and the United States
YANG Yi, LI Chenghuan, LIU Duo, and ZHANG Jiandong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.015
By systematically investigating the relevant codes of bridge maintenance in China and the United States, this paper compared the relevant regulations of steel bridge maintenance from the three aspects of steel bridge inspection, damage assessment, and maintenance and reinforcement and summarized the reference points of the existing maintenance codes for steel bridges, which has important reference value for improving the technical standards of steel bridge maintenance and enhancing the technical level of maintenance.
Influence of curvature radius on mechanical properties of small and medium span continuous rigid frame bridge during construction stages
XIE Yangfu, YE Yuansheng, GUI Shuirong, and YANG Yu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.016
In order to study the mechanical properties and the influence of curvature radius on the mechanical properties of curved rigid frame bridge constructed by span-by-span assembly method, this paper took the continuous rigid frame bridge with a two-box standard section (35 + 35 + 35) m of Hongdu Overpass in Nanchang City as the engineering background. By changing the curvature radius, the influence of curvature radius on the mechanical properties of small- and medium-span continuous rigid frame bridges constructed by span-by-span assembly method during construction was studied. The results show that the mechanical properties such as the main beam stress, vertical displacement, lateral displacement, torque, and bottom stress of the established front span will be affected by the construction of the rear span in the application of the span-by-span assembly method, and the influence increases with the decrease in the curvature radius. When the curvature radius is too small, the mechanical indexes are easy to exceed the safe allowable values. By considering the mechanical properties in the design and construction phase, the curvature radius of such bridges should not be less than 75 m.
Research on monitoring and control of demolition construction of prestressed concrete continuous beam bridge
BAI Yinghua and TANG Xu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.017
The demolition of an old bridge is a complex dynamic process. In order to ensure the safety of the structure in the process of bridge demolition and ensure the smooth and safe demolition of the old bridge, this paper took the demolition construction of a three-span prestressed concrete continuous beam bridge as an example, established the space model of the whole bridge through the finite element simulation modeling software Midas Civil, and calculated the stress and deformation of the structure at each construction stage. At the same time, the stress and linear changes of the main beam at each construction stage were monitored in real time, and the measured data of the two key construction stages when the main beam structure system was transformed were compared with the theoretical data to analyze the stress and linear changes of the structure. The results show that the stress and linear change trend of the main beam structure is basically consistent with the theoretical calculation in the process of bridge demolition and is always within the safe and controllable range.
Analysis on local relative deformation of vertical and horizontal split block section of ultra wide steel box‐girder
LIU Li, PENG Chengming, and LUO Hang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.018
In order to meet the requirement that the channel should not be occupied during the construction of the 4th Bridge over the Panama Canal, an innovative construction scheme was proposed for the erection of the ultra-wide overweight steel box girder with central double cable planes (standard section length of 13 m, width of 51 m, and weight of about 370 t), or in other words, the steel box girder was divided into two horizontal segments after vertical segmentation and then horizontally lifted onto the bridge deck through the cable tower. The steel box girder was moved to the bridge deck crane at the cantilever end, and the tail moved forward and rotated 90° in the air. After adjusting the attitude, the steel box girder was horizontally moved to match the position. In order to understand the deformation of the steel box girder matching after horizontal segmentation and determine a reasonable docking process, the finite element software was used to analyze the local relative deformation of steel box girder installation with horizontal segments, and the results were compared with the whole segment installation. The results show that the method has an obvious horizontal biased load effect, especially in the middle lifting condition, but the deformation of the side web is significantly reduced than that of the middle web when the horizontal displacement is matched, and the maximum seam height difference is 4.2 mm. Compared with the whole segment installation, there will be two vertical and horizontal splicing planes after horizontal segmentation, among which the horizontal splicing plane deformation is larger than that along the bridge. Therefore, it is recommended to match the horizontal splicing plane first and then the remaining area of the horizontal bridge splicing plane after matching the middle web with greater stiffness. The splicing plane matching along the bridge should also prioritize the diaphragms with greater stiffness and then match the local area between the diaphragms. In general, the local relative deformation of the proposed horizontal segmentation scheme is controllable, and it can meet the construction requirements through reasonable matching methods.
Design and experimental study on special spherical support of Pingtang Bridge
TANG Zhi, MA Baihu, DU Bin, XU Xiangdong, and XIA Junyong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.019
The vertical bearing capacity of the 16# pier of Pingtang Bridge is 10 000 kN, and the horizontal bearing capacity along the bridge is 12 000 kN, which is 120% of the vertical bearing capacity. The support angle needs to reach the technical parameter requirements of 0.05 rad, which far exceeds the requirements of 10–40% horizontal force of conventional highway supports. According to the specific engineering situation, a new type of support with a large horizontal bearing capacity was designed. Firstly, the finite element model of the support was established to analyze the mechanical properties of the support, and the performance of the support and the durability of the support material were tested. The results show that there is no obvious stress concentration phenomenon in the new support, and the influence of the longitudinal angle on the stress of each component is greater than that of the transverse angle. The design of the curved rotating sleeve structure of the support can ensure that the horizontal force follows a plane-to-plane transfer. The scale test results of the support meet the requirements of the corresponding specifications, and the support can meet the strength requirements under the limit working conditions without stress damage. The use of an S-Lide wear-resistant sliding block and high-durability anti-corrosion system design can greatly improve the sliding resistance and anti-corrosion of the support.
Study on practical method of safety assessment for bridges under heavy‐cargo transportation
JIANG Xu, WANG Wanfeng, HE Zhensheng, and GAO Xuefeng
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.020
In order to meet the requirements of the industry for the high efficiency, safety, and reliability of the traffic safety assessment of heavy-duty vehicles, this paper proposed a method that combined a real-time monitoring system with a finite element method for the traffic safety assessment of heavy-duty vehicles on bridges and verified the method through practical projects. The paper evaluated the bridge’s technical condition level before the heavy-duty vehicle passes and determined the resistance reduction factor considering the bridge’s technical condition level. The finite element analysis model of the bridge was established, and the reliability of the model was verified by the measured data. On this basis, the safety assessment of the bridge was carried out by the actual load checking method. The bridge was also monitored in real time during the passage of heavy-duty vehicles. The results show that the technical condition level of the bridge is Class A. The finite element model of the real bridge can reliably evaluate the bearing capacity of the bridge. During the passage of heavy-duty vehicles, the bridge is in an elastic state, and the passage of heavy-duty vehicles does not cause damage to the bridge structure.
Research on vibration reduction measures of short‐hole blasting for pile group foundation of bridge
LONG Lidun, JI Zhongyan, LI Shaofang, and ZHOU Xu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.021
In the construction of pile hole blasting of group pile foundation of bridges, due to the small clear distance between piles, the blasting vibration will have adverse effects on the wall protection of adjacent pile holes and the poured pile core concrete. Measures thus should be taken to control the seismic wave vibration velocity. In view of the inapplicability of conventional blasting vibration reduction measures such as reducing charge and setting isolation ditch in the construction of pile group foundation of the bridge, this paper proposed vibration reduction measures such as setting isolation holes and using air bags to replace part of stemming. The feasibility and vibration reduction effect of the two measures were verified by comparative tests, and the practical application was carried out in the construction of the pile foundation of the 4# main tower of Kaizhou Lake Grand Bridge, with good results obtained. In addition, the quality and safety of pile group foundation construction are guaranteed without greatly increasing the cost and reducing the work efficiency, which has a good reference value for the construction of similar projects.
Research and analysis on controlled blasting demolition of continuous thin‐walled box ribbed arch bridge
MA Shaojun, CHEN Huibin, CHAI Wendong, ZHANG Chunquan, and WANG Yuan
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.022
The 1st bridge of the Jialing River in Pengan County is erected over the Jialing River, a tributary of the Yangtze River. Due to earthquakes and perennial high load operation, the overall technical condition is “Class Ⅴ”, which cannot meet the requirements of the design load grade. This bridge is the longest highway bridge dismantled in Sichuan Province. Its structure is a multi-span continuous thin-walled box ribbed arch bridge. In addition, there are obvious diseases, so the demolition is difficult, and the safety risk is great. For the demolition of the bridge by controlled blasting, numerical simulation, shaped charge cutting blasting, long hanging deep hole drilling, and other technical means were adopted, and the demolition work was successfully completed. The technical experience can provide reference for similar bridge demolition.
Installation construction technology of composite girder cable‐stayed bridge superstructure in deep‐cutting gorge
REN Lei, LU Liang, and DONG Zhengliang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.023
In view of the installation problems of superimposed beam cable-stayed bridge across the deep canyon, this paper studied the superimposed beam lifting, transport on beam, and superimposed beam installation and proposed three kinds of lifting technology with tower truss crane, beam lifting door crane, and large tower crane, as well as two kinds of installation technology including piecemeal assembly by full rotating deck crane and whole segment assembly truss deck crane. It also made a relative comparative analysis, solving the difficulty in vertical lifting on such bridges and providing a reference for the construction of the same type of cable-stayed bridges.
Analysis of influence parameters of steel corrugated plate‐concrete composite arch culvert
ZHANG Haijun
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.024
In order to explore the parameter effect of a composite arch culvert with corrugated steel plate and concrete, based on the engineering background of a composite arch culvert, the influence rules of four parameters, namely fill height, pipe diameter, wall thickness, and uneven settlement, on the stress and deformation of the arch culvert were analyzed based on the control variable method. The results show that the deformation and stress of the arch culvert are positively correlated with the fill height h and pipe diameter R. When h < 25 m, the deformation and stress increase linearly with the increase in the fill height, and when h > 25 m, the deformation and stress increase in a curve form. When R < 4 m, both of them increase linearly with the increase in pipe diameter, and when R > 4 m, the curve increases, and the change rate accelerates obviously. When the wall thickness T is 2–6 m, the deformation and stress increase linearly. When T > 6 m, the stress of the corrugated steel plate is basically unchanged. The horizontal uneven settlement has an obvious influence on the stress of the arch culvert, and increasing the pipe diameter can effectively control the additional internal force caused by the uneven settlement.
Research on reasonable completion state and construction stage of Fenghuang Road Bridge
CHEN Qiang, GAO Libao, and DU Hongliang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.025
In order to study the reasonable completion state of Fenghuang Road Bridge and analyze the construction stage, the finite element model was first established by Midas/Civil, and the correlation matrix was extracted. The minimum strain energy of Fenghuang Road Bridge was used as the objective function, and the mathematical optimization model was established by Matlab to determine the reasonable completion state and construction sequence of the bridge. To ensure reasonable cable force of the bridge, the construction cable force was solved by the forward assembly iteration, and the law of the construction cable force was basically the same as that of the bridge cable force. The model met the requirements of the specification according to the design and calculation.
Research on damage location based on time reversal and ultrasound‐probability imaging algorithm
YIN Xinfeng, YANG Jinyi, and ZHANG Ming
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.026
In order to study the location of structural damage, an improved time-reversal (TR)-based ultrasound-probabilistic imaging (TRPDI) algorithm was proposed in this paper. The electrical signal was applied to the piezoelectric ceramics (PZT) attached to the surface of the aluminium plate to generate an ultrasonic Lamb wave with good propagation performance in the aluminium plate. Based on Lamb wave theory and TR theory, the damage index was optimized, and the damage imaging algorithm was used to analyze the damage degree of the specimen and locate the damage. Three different data processing methods were used to obtain the active components in the signal, and the damage existence judgment and damage location research were carried out, respectively. The experiments show that the TRPDI algorithm can improve location accuracy and has great application potential in engineering damage locations.
Experiment research of high pressure jet grouting pile on ultra‐shallow buried tunnel in strong weathered stratum
LU Liyang, LIU Huan, and LI Pinpin
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.027
By taking the ultra-shallow buried construction of Xinwu Tunnel in Luoding–Xinyi Expressway in Guangdong Province as the engineering background, the key construction parameters and formation reinforcement effect of high-pressure rotary churning pile in ultra-shallow buried tunnel surrounding rock of fully weathered strata were compared. The results show that: ① slurry pressure, rotary churning speed, and lifting speed have obvious effects on the static load bearing capacity of a single pile. Under the same static load condition, greater slurry pressure indicates a lower cumulative settlement value of a single pile and a smaller increase in cumulative settlement value, and the change rate of rebound value is basically the same. With the increase in rotary churning speed, the lower cumulative settlement value of a single pile means that the change rate of the cumulative settlement value of a single pile decreases, and the change rate of rebound value decreases. With the increase in lifting speed, the cumulative settlement value of a single pile increases, and the change rate of cumulative settlement value decreases; the change rate of rebound value basically remains unchanged. ②The cement soil of the pile body is uniform and brittle, with high strength, and the formation at the slurry site is mainly a loose silty clay layer and sand-bearing layer. ③After the bottom of the tunnel is strengthened by a high-pressure rotary churning pile, the top surrounding rock is more stable after the excavation of the ultra-shallow buried tunnel, and the cracks between the surrounding rock are filled with cement slurry; the integrity is improved. The pile body effectively limits the deformation of the soil outside the side wall to the inside of the tunnel and plays a certain role in stopping water. The reinforcement by a high-pressure rotary churning pile improves the integrity of surrounding rock, consolidates the soft soil above the tunnel arch, and creates conditions for the safe excavation of the shallow buried section of the tunnel.
Study on parameter optimization of feet‐lock anchor pipes of tunnels in unconsolidated formation
TANG Heqing, JIANG Xishan, and YANG Peng
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.028
In order to give full play to the supporting role of the feet-lock anchor pipe in the tunnel with unconsolidated formation, it is necessary to obtain the optimal construction parameters of the feet-lock anchor pipe. Based on a tunnel project on the Huaping–Lijiang Expressway in Yunnan Province, this paper conducted numerical simulation and field test analysis. By comparing the arch subsidence and horizontal convergence of the supporting structure when the feet-lock anchor pipe with different parameters was constructed, the paper explored the characteristics and causes of the influence of construction parameters on the feet-lock effect. The results show that the feet-lock anchor pipes can effectively reduce the deformation of the supporting structure in unconsolidated formation, and the arch subsidence and horizontal convergence of the tunnel are significantly reduced. In the construction parameters of feet-lock anchor pipes, the angle and length of the anchor pipe have an obvious influence on the feet-lock effect, but the height has little influence. By combining the research conclusion with engineering application and considering the operability and economy, the optimal construction parameters for this kind of formation are proposed.
Simulation study on flame retardant effect of warm‐mixed flame retardant pavement in highway tunnel
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.029
In order to obtain the flame retardant effect of the warm-mixed flame retardant asphalt pavement in highway tunnels, based on the finite element method and thermodynamics theory, the thermal analysis module of Ansys finite element software was used to study the flame retardant effect of ordinary asphalt pavement, flame retardant asphalt pavement, and warm-mixed flame retardant asphalt pavement under different fire scales. The maximum temperature of the three types of pavement increased with the increase in the fire scale. Under any fire scale, the flame retardant effect of the warm-mixed flame retardant asphalt pavement was increased by 4.9%–8.5% compared with that of the ordinary asphalt pavement. The smaller fire scale indicated a more obvious cooling effect. Under the minimum fire scale, the temperature below the asphalt pavement was higher than the aging temperature of the asphalt. When the fire scale was 5–100 MW, the average growth rate of the mixture required to complete the repair of flame retardant asphalt pavement and warm-mixed flame retardant asphalt pavement was −9.3% and −12.8%, respectively. The relationship model of the maximum temperature of pavement and the fire scale was proposed, and the quality of the mixture required for post-disaster repair was calculated, which provided a reference for the prevention and repair of tunnel fires.
Study on arrangement law of grouting bolt in mountain tunnel
ZHAO Licai
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.030
In the sandy soil area with abundant water content, grouted bolts can solve the problems of poor stability of surrounding rock and groundwater erosion in tunnel construction. However, the unreasonable arrangement of grouted bolts will cause the waste of slurry and fail to achieve the predetermined grouting effect. Based on the differential equation of slurry diffusion, this paper realized the numerical simulation of grouted bolts in a tunnel through software secondary development. Combined with mathematical statistics, the influence of the distance of grouted bolts, tunnel radius, and grouting time on the formation of grouting rings in mountain tunnels was studied. The results show that there is a power function relationship between the distance of grouted bolts and the grouting time and an exponential function relationship between tunnel radius and grouting time. In the multi-core circular tunnel, the spacing between grouted bolts in different radius segments needs to be different, and the conversion relationship between the distance of grouted bolts can be completed by the formula obtained by research.
Test and finite element analysis on flexural properties of steel plate‒UHPC composite beam
HUANG Yun, ZHAO Hua, and TU Lei
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.011
In order to study the flexural properties of steel plate-ultra-high performance concrete (UHPC) composite beams, the static test of the flexural properties of a steel sheet-UHPC composite beam was first carried out. Then, Abaqus finite element software was used to simulate the whole process of static loading of the specimen, and different ways were used to simulate the studs in the composite beam. The most appropriate model was thus selected. Finally, based on the calibrated finite element model, the parameters of the steel plate-UHPC composite beam were analyzed, the main parameters included: UHPC compressive strength, steel plate strength, and stud spacing and layout. The results show that in the finite element simulation analysis, the surface-surface contact finite element model is used, and the simulation analysis results are in good agreement with the measured values, which can better reflect the change law of deflection, strain, and slip in the steel plate-UHPC composite beam and be used as a reference for the subsequent finite element simulation analysis of steel plate-UHPC composite beams. The influence of each parameter on the ultimate bearing capacity of steel plate-UHPC composite beam in descending order is as follows: steel plate strength >UHPC compressive strength > stud spacing. In the structural design, it is necessary to pay attention to the selection and arrangement of studs in the shear section, while the studs in the pure section can be relatively weakened.
Study on reliability of special shaped arch bridge with spatial three‐cable‐plane inclined suspenders under live load
ZHU Liming, SHEN Kun, and WANG Xingyun
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.012
Because the structure of a special shaped arch bridge is complicated, there are few studies on the fatigue reliability of its suspender. In order to study the fatigue reliability of the suspender of complex shaped arch bridges under live load, the actual project of a 157 m through-type steel arch bridge with three-cable-plane inclined suspenders with special shaped tie bars was studied. The fatigue reliability formula based on Weibull distribution was applied to analyze the fatigue reliability of the suspender under different live load conditions. The results show that the design live load ensures a higher safety reserve and meets the allowable stress requirements of the code, but the live load stress amplitude of some short suspenders in the midspan is large, and the fatigue reliability index is close to the critical value. Therefore, the target value given in the code can be appropriately adjusted. During construction and operation, special attention should be paid to the stress of the short suspender to ensure the safety of the structure.
Research on bridge technical condition evaluation system based on BIM
XIA Zili, JING Qiang, GAO Wenbo, HUANG Liguan, and WU Xiaodong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.013
There are some practical difficulties in bridge technical condition assessment, such as low visualization degree, strong subjectivity of assessment, low efficiency of disease location, and poor continuity of assessment data. In view of the requirements of bridge technical condition assessment and the above-mentioned problems, this paper reviewed the standard system of bridge technical condition assessment in China and the application of BIM in bridge operation and maintenance, analyzed the modelling points and assessment business processes of bridge BIM model, and designed the overall framework and business module functions of the BIM-based technical condition assessment system. The bridge technical condition assessment system was developed based on the Qingzhou Bridge of Hong Kong-Zhuhai-Macao Bridge project and was initially applied to the bridge technical condition assessment, so as to improve the visualization level and efficiency of on-site operations, standardize the storage of bridge assessment data, and achieve long-term tracking of bridge service performance.
Study on pavement structure performance based on polymer alloy material for steel deck pavement
YANG Bo, HE Zhaoyi, LIU Pan, LI Kai, SHENG Xingyue, and LI Lu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.014
Based on the characteristics of light weight and high strength of polymer alloy materials, three new steel bridge deck pavement structures based on polymer alloy materials were proposed in this paper. Their high temperature performance, interface bonding performance, fatigue resistance, and skid resistance were investigated, and the performance performance was compared with that of traditional pavement structures. The test results show that the thickness of the pavement layer has a greater influence on the high temperature performance of “polymer alloy material + high-elasticity modified asphalt concrete SMA10” but has less influence on the high temperature performance of “polymer alloy material + high-toughness epoxy asphalt concrete EA10” and “poured asphalt concrete GA10 + polymer alloy material”. The polymer alloy pavement structure has good high temperature performance, interface bonding performance, and fatigue resistance, and the overall performance is similar to that of cast asphalt concrete and epoxy asphalt concrete pavement structures, which can fully meet the requirements of steel bridge deck pavement for material and structure and reduce the dead weight of the pavement layer, so as to achieve lightweight and high-strength pavement of steel bridge decks.
Comparative study on steel bridge maintenance and technical specifications of China and the United States
YANG Yi, LI Chenghuan, LIU Duo, and ZHANG Jiandong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.015
By systematically investigating the relevant codes of bridge maintenance in China and the United States, this paper compared the relevant regulations of steel bridge maintenance from the three aspects of steel bridge inspection, damage assessment, and maintenance and reinforcement and summarized the reference points of the existing maintenance codes for steel bridges, which has important reference value for improving the technical standards of steel bridge maintenance and enhancing the technical level of maintenance.
Influence of curvature radius on mechanical properties of small and medium span continuous rigid frame bridge during construction stages
XIE Yangfu, YE Yuansheng, GUI Shuirong, and YANG Yu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.016
In order to study the mechanical properties and the influence of curvature radius on the mechanical properties of curved rigid frame bridge constructed by span-by-span assembly method, this paper took the continuous rigid frame bridge with a two-box standard section (35 + 35 + 35) m of Hongdu Overpass in Nanchang City as the engineering background. By changing the curvature radius, the influence of curvature radius on the mechanical properties of small- and medium-span continuous rigid frame bridges constructed by span-by-span assembly method during construction was studied. The results show that the mechanical properties such as the main beam stress, vertical displacement, lateral displacement, torque, and bottom stress of the established front span will be affected by the construction of the rear span in the application of the span-by-span assembly method, and the influence increases with the decrease in the curvature radius. When the curvature radius is too small, the mechanical indexes are easy to exceed the safe allowable values. By considering the mechanical properties in the design and construction phase, the curvature radius of such bridges should not be less than 75 m.
Research on monitoring and control of demolition construction of prestressed concrete continuous beam bridge
BAI Yinghua and TANG Xu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.017
The demolition of an old bridge is a complex dynamic process. In order to ensure the safety of the structure in the process of bridge demolition and ensure the smooth and safe demolition of the old bridge, this paper took the demolition construction of a three-span prestressed concrete continuous beam bridge as an example, established the space model of the whole bridge through the finite element simulation modeling software Midas Civil, and calculated the stress and deformation of the structure at each construction stage. At the same time, the stress and linear changes of the main beam at each construction stage were monitored in real time, and the measured data of the two key construction stages when the main beam structure system was transformed were compared with the theoretical data to analyze the stress and linear changes of the structure. The results show that the stress and linear change trend of the main beam structure is basically consistent with the theoretical calculation in the process of bridge demolition and is always within the safe and controllable range.
Analysis on local relative deformation of vertical and horizontal split block section of ultra wide steel box‐girder
LIU Li, PENG Chengming, and LUO Hang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.018
In order to meet the requirement that the channel should not be occupied during the construction of the 4th Bridge over the Panama Canal, an innovative construction scheme was proposed for the erection of the ultra-wide overweight steel box girder with central double cable planes (standard section length of 13 m, width of 51 m, and weight of about 370 t), or in other words, the steel box girder was divided into two horizontal segments after vertical segmentation and then horizontally lifted onto the bridge deck through the cable tower. The steel box girder was moved to the bridge deck crane at the cantilever end, and the tail moved forward and rotated 90° in the air. After adjusting the attitude, the steel box girder was horizontally moved to match the position. In order to understand the deformation of the steel box girder matching after horizontal segmentation and determine a reasonable docking process, the finite element software was used to analyze the local relative deformation of steel box girder installation with horizontal segments, and the results were compared with the whole segment installation. The results show that the method has an obvious horizontal biased load effect, especially in the middle lifting condition, but the deformation of the side web is significantly reduced than that of the middle web when the horizontal displacement is matched, and the maximum seam height difference is 4.2 mm. Compared with the whole segment installation, there will be two vertical and horizontal splicing planes after horizontal segmentation, among which the horizontal splicing plane deformation is larger than that along the bridge. Therefore, it is recommended to match the horizontal splicing plane first and then the remaining area of the horizontal bridge splicing plane after matching the middle web with greater stiffness. The splicing plane matching along the bridge should also prioritize the diaphragms with greater stiffness and then match the local area between the diaphragms. In general, the local relative deformation of the proposed horizontal segmentation scheme is controllable, and it can meet the construction requirements through reasonable matching methods.
Design and experimental study on special spherical support of Pingtang Bridge
TANG Zhi, MA Baihu, DU Bin, XU Xiangdong, and XIA Junyong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.019
The vertical bearing capacity of the 16# pier of Pingtang Bridge is 10 000 kN, and the horizontal bearing capacity along the bridge is 12 000 kN, which is 120% of the vertical bearing capacity. The support angle needs to reach the technical parameter requirements of 0.05 rad, which far exceeds the requirements of 10–40% horizontal force of conventional highway supports. According to the specific engineering situation, a new type of support with a large horizontal bearing capacity was designed. Firstly, the finite element model of the support was established to analyze the mechanical properties of the support, and the performance of the support and the durability of the support material were tested. The results show that there is no obvious stress concentration phenomenon in the new support, and the influence of the longitudinal angle on the stress of each component is greater than that of the transverse angle. The design of the curved rotating sleeve structure of the support can ensure that the horizontal force follows a plane-to-plane transfer. The scale test results of the support meet the requirements of the corresponding specifications, and the support can meet the strength requirements under the limit working conditions without stress damage. The use of an S-Lide wear-resistant sliding block and high-durability anti-corrosion system design can greatly improve the sliding resistance and anti-corrosion of the support.
Study on practical method of safety assessment for bridges under heavy‐cargo transportation
JIANG Xu, WANG Wanfeng, HE Zhensheng, and GAO Xuefeng
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.020
In order to meet the requirements of the industry for the high efficiency, safety, and reliability of the traffic safety assessment of heavy-duty vehicles, this paper proposed a method that combined a real-time monitoring system with a finite element method for the traffic safety assessment of heavy-duty vehicles on bridges and verified the method through practical projects. The paper evaluated the bridge’s technical condition level before the heavy-duty vehicle passes and determined the resistance reduction factor considering the bridge’s technical condition level. The finite element analysis model of the bridge was established, and the reliability of the model was verified by the measured data. On this basis, the safety assessment of the bridge was carried out by the actual load checking method. The bridge was also monitored in real time during the passage of heavy-duty vehicles. The results show that the technical condition level of the bridge is Class A. The finite element model of the real bridge can reliably evaluate the bearing capacity of the bridge. During the passage of heavy-duty vehicles, the bridge is in an elastic state, and the passage of heavy-duty vehicles does not cause damage to the bridge structure.
Research on vibration reduction measures of short‐hole blasting for pile group foundation of bridge
LONG Lidun, JI Zhongyan, LI Shaofang, and ZHOU Xu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.021
In the construction of pile hole blasting of group pile foundation of bridges, due to the small clear distance between piles, the blasting vibration will have adverse effects on the wall protection of adjacent pile holes and the poured pile core concrete. Measures thus should be taken to control the seismic wave vibration velocity. In view of the inapplicability of conventional blasting vibration reduction measures such as reducing charge and setting isolation ditch in the construction of pile group foundation of the bridge, this paper proposed vibration reduction measures such as setting isolation holes and using air bags to replace part of stemming. The feasibility and vibration reduction effect of the two measures were verified by comparative tests, and the practical application was carried out in the construction of the pile foundation of the 4# main tower of Kaizhou Lake Grand Bridge, with good results obtained. In addition, the quality and safety of pile group foundation construction are guaranteed without greatly increasing the cost and reducing the work efficiency, which has a good reference value for the construction of similar projects.
Research and analysis on controlled blasting demolition of continuous thin‐walled box ribbed arch bridge
MA Shaojun, CHEN Huibin, CHAI Wendong, ZHANG Chunquan, and WANG Yuan
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.022
The 1st bridge of the Jialing River in Pengan County is erected over the Jialing River, a tributary of the Yangtze River. Due to earthquakes and perennial high load operation, the overall technical condition is “Class Ⅴ”, which cannot meet the requirements of the design load grade. This bridge is the longest highway bridge dismantled in Sichuan Province. Its structure is a multi-span continuous thin-walled box ribbed arch bridge. In addition, there are obvious diseases, so the demolition is difficult, and the safety risk is great. For the demolition of the bridge by controlled blasting, numerical simulation, shaped charge cutting blasting, long hanging deep hole drilling, and other technical means were adopted, and the demolition work was successfully completed. The technical experience can provide reference for similar bridge demolition.
Installation construction technology of composite girder cable‐stayed bridge superstructure in deep‐cutting gorge
REN Lei, LU Liang, and DONG Zhengliang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.023
In view of the installation problems of superimposed beam cable-stayed bridge across the deep canyon, this paper studied the superimposed beam lifting, transport on beam, and superimposed beam installation and proposed three kinds of lifting technology with tower truss crane, beam lifting door crane, and large tower crane, as well as two kinds of installation technology including piecemeal assembly by full rotating deck crane and whole segment assembly truss deck crane. It also made a relative comparative analysis, solving the difficulty in vertical lifting on such bridges and providing a reference for the construction of the same type of cable-stayed bridges.
Analysis of influence parameters of steel corrugated plate‐concrete composite arch culvert
ZHANG Haijun
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.024
In order to explore the parameter effect of a composite arch culvert with corrugated steel plate and concrete, based on the engineering background of a composite arch culvert, the influence rules of four parameters, namely fill height, pipe diameter, wall thickness, and uneven settlement, on the stress and deformation of the arch culvert were analyzed based on the control variable method. The results show that the deformation and stress of the arch culvert are positively correlated with the fill height h and pipe diameter R. When h < 25 m, the deformation and stress increase linearly with the increase in the fill height, and when h > 25 m, the deformation and stress increase in a curve form. When R < 4 m, both of them increase linearly with the increase in pipe diameter, and when R > 4 m, the curve increases, and the change rate accelerates obviously. When the wall thickness T is 2–6 m, the deformation and stress increase linearly. When T > 6 m, the stress of the corrugated steel plate is basically unchanged. The horizontal uneven settlement has an obvious influence on the stress of the arch culvert, and increasing the pipe diameter can effectively control the additional internal force caused by the uneven settlement.
Research on reasonable completion state and construction stage of Fenghuang Road Bridge
CHEN Qiang, GAO Libao, and DU Hongliang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.025
In order to study the reasonable completion state of Fenghuang Road Bridge and analyze the construction stage, the finite element model was first established by Midas/Civil, and the correlation matrix was extracted. The minimum strain energy of Fenghuang Road Bridge was used as the objective function, and the mathematical optimization model was established by Matlab to determine the reasonable completion state and construction sequence of the bridge. To ensure reasonable cable force of the bridge, the construction cable force was solved by the forward assembly iteration, and the law of the construction cable force was basically the same as that of the bridge cable force. The model met the requirements of the specification according to the design and calculation.
Research on damage location based on time reversal and ultrasound‐probability imaging algorithm
YIN Xinfeng, YANG Jinyi, and ZHANG Ming
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.026
In order to study the location of structural damage, an improved time-reversal (TR)-based ultrasound-probabilistic imaging (TRPDI) algorithm was proposed in this paper. The electrical signal was applied to the piezoelectric ceramics (PZT) attached to the surface of the aluminium plate to generate an ultrasonic Lamb wave with good propagation performance in the aluminium plate. Based on Lamb wave theory and TR theory, the damage index was optimized, and the damage imaging algorithm was used to analyze the damage degree of the specimen and locate the damage. Three different data processing methods were used to obtain the active components in the signal, and the damage existence judgment and damage location research were carried out, respectively. The experiments show that the TRPDI algorithm can improve location accuracy and has great application potential in engineering damage locations.
Experiment research of high pressure jet grouting pile on ultra‐shallow buried tunnel in strong weathered stratum
LU Liyang, LIU Huan, and LI Pinpin
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.027
By taking the ultra-shallow buried construction of Xinwu Tunnel in Luoding–Xinyi Expressway in Guangdong Province as the engineering background, the key construction parameters and formation reinforcement effect of high-pressure rotary churning pile in ultra-shallow buried tunnel surrounding rock of fully weathered strata were compared. The results show that: ① slurry pressure, rotary churning speed, and lifting speed have obvious effects on the static load bearing capacity of a single pile. Under the same static load condition, greater slurry pressure indicates a lower cumulative settlement value of a single pile and a smaller increase in cumulative settlement value, and the change rate of rebound value is basically the same. With the increase in rotary churning speed, the lower cumulative settlement value of a single pile means that the change rate of the cumulative settlement value of a single pile decreases, and the change rate of rebound value decreases. With the increase in lifting speed, the cumulative settlement value of a single pile increases, and the change rate of cumulative settlement value decreases; the change rate of rebound value basically remains unchanged. ②The cement soil of the pile body is uniform and brittle, with high strength, and the formation at the slurry site is mainly a loose silty clay layer and sand-bearing layer. ③After the bottom of the tunnel is strengthened by a high-pressure rotary churning pile, the top surrounding rock is more stable after the excavation of the ultra-shallow buried tunnel, and the cracks between the surrounding rock are filled with cement slurry; the integrity is improved. The pile body effectively limits the deformation of the soil outside the side wall to the inside of the tunnel and plays a certain role in stopping water. The reinforcement by a high-pressure rotary churning pile improves the integrity of surrounding rock, consolidates the soft soil above the tunnel arch, and creates conditions for the safe excavation of the shallow buried section of the tunnel.
Study on parameter optimization of feet‐lock anchor pipes of tunnels in unconsolidated formation
TANG Heqing, JIANG Xishan, and YANG Peng
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.028
In order to give full play to the supporting role of the feet-lock anchor pipe in the tunnel with unconsolidated formation, it is necessary to obtain the optimal construction parameters of the feet-lock anchor pipe. Based on a tunnel project on the Huaping–Lijiang Expressway in Yunnan Province, this paper conducted numerical simulation and field test analysis. By comparing the arch subsidence and horizontal convergence of the supporting structure when the feet-lock anchor pipe with different parameters was constructed, the paper explored the characteristics and causes of the influence of construction parameters on the feet-lock effect. The results show that the feet-lock anchor pipes can effectively reduce the deformation of the supporting structure in unconsolidated formation, and the arch subsidence and horizontal convergence of the tunnel are significantly reduced. In the construction parameters of feet-lock anchor pipes, the angle and length of the anchor pipe have an obvious influence on the feet-lock effect, but the height has little influence. By combining the research conclusion with engineering application and considering the operability and economy, the optimal construction parameters for this kind of formation are proposed.
Simulation study on flame retardant effect of warm‐mixed flame retardant pavement in highway tunnel
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.029
In order to obtain the flame retardant effect of the warm-mixed flame retardant asphalt pavement in highway tunnels, based on the finite element method and thermodynamics theory, the thermal analysis module of Ansys finite element software was used to study the flame retardant effect of ordinary asphalt pavement, flame retardant asphalt pavement, and warm-mixed flame retardant asphalt pavement under different fire scales. The maximum temperature of the three types of pavement increased with the increase in the fire scale. Under any fire scale, the flame retardant effect of the warm-mixed flame retardant asphalt pavement was increased by 4.9%–8.5% compared with that of the ordinary asphalt pavement. The smaller fire scale indicated a more obvious cooling effect. Under the minimum fire scale, the temperature below the asphalt pavement was higher than the aging temperature of the asphalt. When the fire scale was 5–100 MW, the average growth rate of the mixture required to complete the repair of flame retardant asphalt pavement and warm-mixed flame retardant asphalt pavement was −9.3% and −12.8%, respectively. The relationship model of the maximum temperature of pavement and the fire scale was proposed, and the quality of the mixture required for post-disaster repair was calculated, which provided a reference for the prevention and repair of tunnel fires.
Study on arrangement law of grouting bolt in mountain tunnel
ZHAO Licai
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.030
In the sandy soil area with abundant water content, grouted bolts can solve the problems of poor stability of surrounding rock and groundwater erosion in tunnel construction. However, the unreasonable arrangement of grouted bolts will cause the waste of slurry and fail to achieve the predetermined grouting effect. Based on the differential equation of slurry diffusion, this paper realized the numerical simulation of grouted bolts in a tunnel through software secondary development. Combined with mathematical statistics, the influence of the distance of grouted bolts, tunnel radius, and grouting time on the formation of grouting rings in mountain tunnels was studied. The results show that there is a power function relationship between the distance of grouted bolts and the grouting time and an exponential function relationship between tunnel radius and grouting time. In the multi-core circular tunnel, the spacing between grouted bolts in different radius segments needs to be different, and the conversion relationship between the distance of grouted bolts can be completed by the formula obtained by research.
Pavement Structure and Materials
Experimental study on the diagonal shear of asphalt mixture at micro‐surfaces
HUANG Weirong, YANG Yuzhu, WANG Cheng, HUANG Feng, and YANG Bo
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.031
A new 45° diagonal shear test was conducted to study the shear properties of the SBR-modified emulsified asphalt mixture at the micro-surface under the influence of different loading rates, different interface states, and different temperatures and water. The shear failure forms at the micro-surface at different temperatures were explained, and the effects of viscous layer oil, soil, and water on the shear strength at the micro-surface were analyzed. The results show that a faster loading rate at the micro-surface indicates higher shear strength. The shear failure mode of micro-surface at normal temperature is mainly an interlayer shear failure, while that at high temperature is a self-shear failure. When the surface of the original pavement is rough, the spread of viscous layer oil has little contribution to the increase in interlayer shear strength, and the mud water will reduce the interlayer shear strength at the micro-surface. Water immersion will damage the interlayer shear strength at the micro-surface, and spraying viscous layer oil can effectively improve the water damage resistance of the interface between the micro-surface and the original pavement.
Study on thermal property of fast growing grass fiber and its asphalt mortar
XIA Chaoming, JIANG Kang, WU Chaofan, and LIU Kefei
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.032
In order to investigate the thermal properties of fast-growing grass fiber and its asphalt mortar, the physical properties and thermal properties of bamboo fiber, reed fiber, and its asphalt mortar were tested and compared with those of lignin fiber and its asphalt mortar by physical property test, thermal weight loss test, and differential scanning calorimetry test. The results show that the addition of plant fiber can effectively improve the high temperature performance of asphalt, but it has a slight inhibition effect on the low temperature performance of asphalt. The quality loss of plant fiber in different temperature ranges is the same. Among the three plant fibers, lignin fiber has the best thermal stability, followed by bamboo fiber and reed fiber. Plant fiber can effectively improve the thermal melting property of asphalt mortar, improve the thermal stability of asphalt mortar, and reduce the temperature sensitivity. Asphalt mortar of bamboo fiber has the best low temperature cracking resistance and temperature sensitivity, and the low temperature stability of fast-growing grass fiber is better than that of lignin fiber.
Uniaxial shear test and mesoscopic numerical simulation of cemental soil based on PFC2D method
YANG Zhihui and LI Shanhua
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.033
Uniaxial compression tests were carried out on stable soft soil samples with different cement contents. Based on the test results, a mesoscopic numerical simulation of PFC2D discrete element particle flow during soil sample deformation was conducted to analyze the mechanical behavior and displacement field distribution of cement soil after failure. The results show that with the increase in cement content, the uniaxial shear strength and elastic modulus of the solidified soft soil sample show an exponential function and rise, and the failure strain shows a quadratic function with the increase in cement content. The mechanical parameters and stress-strain curves of cement soil samples obtained by PFC2D discrete element particle flow simulation are close to the test results, and the discrete element simulation results show that the cement content has a significant effect on the mechanical properties of soil. With the increase in cement content, the failure mode of solidified soft soil gradually changes from crushing failure to shear failure. The displacement vector field obtained by discrete element simulation accurately reflects the failure mode characteristics of cement-solidified soft soil under uniaxial compression load.
Study on effect of fiber stabilizers on water temperature cycle damage resistance of drainage asphalt mixtures
LIU Fuming, WU Di, HE Qingde, and YANG Zhiping
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.034
In order to study the effect of fiber stabilizer on the water temperature cycle damage resistance of drainage asphalt mixture, drainage asphalt mixture without fiber stabilizer and with wood fiber, polyester fiber, and basalt fiber, respectively, were compared through tests. By standard dispersion test and immersed dispersion test, the anti-spalling ability of the mixture was analyzed. Under the same asphalt condition, the standard dispersion loss of the drainage asphalt mixture was reduced to different degrees after adding fiber stabilizer, which could increase the anti-spalling property of the drainage asphalt mixture to some extent. The splitting, indirect tensile, and rutting tests were carried out on samples with and without water temperature cycle damage to analyze the water temperature cycle damage resistance of the mixture. The splitting strength of the drainage asphalt mixture increased after adding fiber stabilizer. The indirect tensile test finds that the stiffness modulus of the drainage asphalt mixture is increased after adding fiber stabilizer, and the low-temperature cracking resistance of the asphalt mixture with basalt fiber is the best, followed by wood fiber. The rutting test shows that the addition of basalt fiber stabilizer has the most obvious improvement on the dynamic stability of the drainage asphalt mixture. The results show that the addition of polyester fiber and basalt fiber can obviously improve the influence of the water immersion environment on the spalling of the drainage asphalt mixture, and basalt fiber can obviously improve the water temperature cycle damage resistance, low temperature cracking resistance, and high-temperature stability of the mixture.
Experimental analysis on recycling and mechanical properties of waste cement
CHEN Liang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.035
In order to recycle waste cement, construction waste cement materials were collected in the laboratory, and they were crushed, ground, and heat treated to facilitate reuse. Then, the waste cement was combined with the commonly used active fly ash admixture to prepare a new cement material for test analysis. The results show that the new cement material produced by industrial by-product, fly ash and waste cement material is feasible. A small amount of construction waste cement material (about 5%) can increase the 28-day compressive strength of cement by more than 50%, and the compressive strength of the prepared building material can reach about 90 MPa.
Experimental study on characteristics and stability of different aged steel slag aggregate
ZHANG Hongri, WANG Guiyao, FENG Jian, LAN Tianzhu, and WU Tao
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.036
Steel slag aggregate has good building material properties, but the utilization rate of steel slag in road engineering is low at present. In this paper, the chemical composition, basic physical and mechanical indexes, f⁃CaO, f⁃MgO, pulverization rate, CRB expansion rate, and other indexes of open-air aged steel slag aggregate in Fangchenggang, Guangxi Province for 0, 6, and 12 months were studied. The results show that the physical and mechanical properties of steel slag aggregate basically meet the requirements of road base materials and subgrade fillers, but the indexes of f⁃CaO, pulverization rate, and CRB expansion rate of steel slag aggregate aged 0 and 6 months fail to meet the requirements of road base and backfill materials. The steel slag aggregate aged 12 months is slightly less than the standard limit. It can be seen that the steel slag aggregate used for road base and backfill materials must be aged in the open air for at least 12 months to meet the road stability requirements.
Influence factors of deicing and thaw performance of asphalt mixture with low freezing point
ZHOU Shuiwen, LIN Fang, ZHANG Xiaohua, ZHANG Lingbo, and JIANG Haoqiu
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.037
The conductivity test was used to study the release law of thawing and deicing components. The freezing test was used to study the cooling law of the mixture, and the thawing rate test was used to study the thawing and deicing performance. The results show that the release of thawing and deicing components of materials with a low freezing point is temperature-dependent, and the release at the high temperature is 3.49–3.77 times that at the low temperature. The granular materials tend to dissolve in water, which results in the release rate of thawing and deicing components faster than that of the filler materials. The freezing process is divided into three stages. The freezing point and duration of the freezing stage are affected by the type and amount of material, as well as the water content, and the freezing point of ZG-10S is the lowest. Increasing the dosage and decreasing the water content are equivalent to increasing the concentration of the solution, which can effectively reduce the freezing point. The melting time has the greatest and most significant influence on the thawing and deicing performance, followed by temperature because the temperature dependence of the release rate determines the limited effect of thawing and deicing.
Study on pavement performance of waterborne epoxy emulsified asphalt and its application in micro‐surface
JIANG Hai and LIU Dachang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.038
In order to improve the pavement performance at micro-surface, waterborne epoxy resin was used to modify the emulsified asphalt, and the compatibility, microstructure, mechanical properties, rheological properties, and pavement performance of mixtures of the modified emulsified asphalt were studied. The storage stability test shows that the epoxy emulsion has good compatibility with emulsified asphalt. With the increase in waterborne epoxy resin content, the modified emulsified asphalt tends to form an epoxy resin-dominated skeleton structure. At the same time, with the increase in waterborne epoxy resin content, the adhesion and mechanical properties of emulsified asphalt and aggregate are significantly improved. At 20% content, the bonding strength is increased by more than two times, and the shear strength is increased by more than one time. Rheological tests show that the waterborne epoxy resin can improve the rutting resistance and elastic recovery rate of emulsified asphalt, and the high temperature performance is significantly improved. The research on the performance of the mixture at the micro-surface shows that the waterborne epoxy resin can significantly improve the water stability and rutting resistance of the emulsified asphalt, and the water stability and rutting resistance of the mixture tend to be stable when the content reaches 20%. In summary, for the modified emulsified asphalt system in this paper, it is recommended that the content of waterborne epoxy resin should be 10%–20%.
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.039
In order to improve the crack resistance of recycled asphalt mixture, a new styrenic block copolymer (SBS)/rubber composite modified asphalt with excellent crack resistance was proposed for the regeneration of reclaimed asphalt pavement (RAP). Based on the creep of low temperature bending beam, confined temperature stress, and four-point bending fatigue test, the low temperature cracking resistance and fatigue cracking performance of composite modified asphalt and SBS-modified asphalt were studied. The results show that the addition of rubber can improve the low temperature and medium temperature crack resistance of recycled asphalt concrete, which may be related to the propagation of micro-cracks formed in the initial cracking of the mixture into the polymer network to absorb the fracture energy and inhibit the further development of micro-cracks. Further analysis of the fracture temperature shows that the composite modified asphalt mixture can extend the service temperature range of the pavement by about 6 °C than the ordinary SBS-modified asphalt mixture, which is conducive to the promotion and application of recycled asphalt mixture in the cold area of northwest China.
Study on anti‐scattering performance of asphalt concrete on aggregate scattering pavement of highway
YANG Siyuan and CHEN Guiliang
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.040
Due to the lack of quantitative evaluation methods for aggregate scattering degree of expressway asphalt pavement in China and abroad, according to the disease characteristics of surface layer spalling, this paper adopted the Cantabro standard dispersion test to sample the concrete of the section with aggregate scattering of Huangqunan Expressway (G3) in Zhejiang Province. The dispersion impact damage modes of the mixture with different severity were analyzed, and the anti-dispersion performance of concrete was evaluated by mass loss rate and water absorption rate. The results show that aggregate scattering will reduce the density of the concrete structure at the surface layer, and the anti-dispersion performance of the damaged section is lower than that of the normal road surface. A more serious appearance scattering degree means a higher water absorption rate, lower anti-dispersion performance of the concrete and more broken specimens generated by the dispersion impact. Finally, based on the test results, the relevant suggestions for the treatment of aggregate scattering are put forward.
Study on the effect of quicklime on the properties of cold mix asphalt
LIU Tao, YI Ming, and SONG Tao
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.041
The low initial strength of cold mixed asphalt mixture leads to the delay of traffic opening time, and the large void ratio leads to poor water stability and other problems, which seriously hinder the development of cold mixed environment-friendly construction mode. In this paper, based on the principle that the heat of quicklime in the presence of water promotes the rapid loss of water in the cold mixed mixture, the mixing test and cohesion test of the MS-3 slurry cold mixed asphalt mixture with quicklime were carried out to explore the influence of quicklime on the demulsification time and cohesion. Then, the effect of quicklime on the initial strength and water stability of the cold mixed mixture was verified by testing the void ratio and uniaxial penetration strength of the AC-13 cold mixed asphalt mixture. The test results show that the process of demulsification of the cold mixed mixture is accelerated by the reaction of quicklime with water and the formation of alkaline calcium hydroxide, and the formation of early strength can greatly shorten the time of traffic opening. At the same time, the composite gelling structure has a significant effect on improving the overall strength and water stability of the pavement.
Traffic Engineering and Management
Research on design process of toll interchange‐expressway in the area of Funiu Mountain
ZHANG Jie, YANG Qing, and CHAI Xiaolong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.042
Currently, the expressways under construction in Henan Province are mainly concentrated in the Funiu Mountain area in the west, such as Yaoshan–Luanchuan–Xixia Expressway, Xixia–Xichuan Expressway, Yingchi–Luanchuan Expressway, and Luanchuan–Lushi Expressway. These projects are characterized by complex terrain conditions, difficult design, large-scale engineering, and a cluster of long tunnels and grand bridges. Under such complex conditions, how to arrange the interchange reasonably and ensure the optimal project plan becomes the key point of successful project design. This paper summarized the typical characteristics of toll interchange in Funiu Mountain area in recent years and put forward the design process of design preparation, control factor analysis, scheme formulation, and determination of the optimal scheme. In addition, the stage design process of Jiguandong Interchange over the Luanchuan–Lushi Expressway in Henan Province was analyzed.
Variable speed limit control method for highway under dense fog
SUN Jiancheng and QIAO Jiaxing
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.043
In order to solve the problem of traffic safety on expressways under dense fog and change the original fixed speed limit measures, a variable speed limit control method based on the safe allowable speed was proposed. The speed limit value was calculated based on the regulations in road traffic safety law on the speed under dense fog by considering that the traffic law does not mention the road alignment conditions, road conditions, and other factors, and the monitor data was used to approximate replace the data of individual vehicles for data optimization, and the safe speed and safe distance of vehicles under dense fog were obtained. Based on this information, the paper provided a basis for setting dynamic variable speed limit information board and further determined the control flow of variable speed limit. The simulation test results of VISSIM show that compared with the fixed speed limit control, the minimum average speed of the variable speed control section is increased by 12.16%, and the maximum difference of average speed is decreased by 26.37%. Compared with the traditional fixed speed limit method, the variable speed limit control method can effectively guarantee travel safety and improve travel efficiency on expressways under dense fog.
Study on dynamic allocation optimization of highway pavement maintenance funds
ZOU Yi
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.044
The conflict between the lack of maintenance funds and the growth of maintenance demand restricts the improvement of highway pavement technologies. In this paper, the state space of pavement maintenance demand was defined by the technical condition of the pavement, and the state of demand under different maintenance measures was designed as a Markov decision process. The dynamic allocation optimization model of highway pavement maintenance funds was established, and the corresponding genetic algorithm was designed. Finally, an example was given to simulate the optimized model. The results show that the Markov decision process can dynamically allocate highway pavement maintenance funds, make the whole pavement maintenance demand state tend to be smooth, and maximize the improvement effect of pavement technical conditions.
Research on design process of toll interchange‐expressway in the area of Funiu Mountain
ZHANG Jie, YANG Qing, and CHAI Xiaolong
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.042
Currently, the expressways under construction in Henan Province are mainly concentrated in the Funiu Mountain area in the west, such as Yaoshan–Luanchuan–Xixia Expressway, Xixia–Xichuan Expressway, Yingchi–Luanchuan Expressway, and Luanchuan–Lushi Expressway. These projects are characterized by complex terrain conditions, difficult design, large-scale engineering, and a cluster of long tunnels and grand bridges. Under such complex conditions, how to arrange the interchange reasonably and ensure the optimal project plan becomes the key point of successful project design. This paper summarized the typical characteristics of toll interchange in Funiu Mountain area in recent years and put forward the design process of design preparation, control factor analysis, scheme formulation, and determination of the optimal scheme. In addition, the stage design process of Jiguandong Interchange over the Luanchuan–Lushi Expressway in Henan Province was analyzed.
Variable speed limit control method for highway under dense fog
SUN Jiancheng and QIAO Jiaxing
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.043
In order to solve the problem of traffic safety on expressways under dense fog and change the original fixed speed limit measures, a variable speed limit control method based on the safe allowable speed was proposed. The speed limit value was calculated based on the regulations in road traffic safety law on the speed under dense fog by considering that the traffic law does not mention the road alignment conditions, road conditions, and other factors, and the monitor data was used to approximate replace the data of individual vehicles for data optimization, and the safe speed and safe distance of vehicles under dense fog were obtained. Based on this information, the paper provided a basis for setting dynamic variable speed limit information board and further determined the control flow of variable speed limit. The simulation test results of VISSIM show that compared with the fixed speed limit control, the minimum average speed of the variable speed control section is increased by 12.16%, and the maximum difference of average speed is decreased by 26.37%. Compared with the traditional fixed speed limit method, the variable speed limit control method can effectively guarantee travel safety and improve travel efficiency on expressways under dense fog.
Study on dynamic allocation optimization of highway pavement maintenance funds
ZOU Yi
Date posted: 3-17-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.01.044
The conflict between the lack of maintenance funds and the growth of maintenance demand restricts the improvement of highway pavement technologies. In this paper, the state space of pavement maintenance demand was defined by the technical condition of the pavement, and the state of demand under different maintenance measures was designed as a Markov decision process. The dynamic allocation optimization model of highway pavement maintenance funds was established, and the corresponding genetic algorithm was designed. Finally, an example was given to simulate the optimized model. The results show that the Markov decision process can dynamically allocate highway pavement maintenance funds, make the whole pavement maintenance demand state tend to be smooth, and maximize the improvement effect of pavement technical conditions.
