摘要：
To study the evolution of the rheological properties of warm mix asphalt (WMA) and its mastic viscoelastic drive prediction model, different dosages of Sasobit (S) and Evotherm 3G (G) WMA were prepared. The temperature sensitivity, high temperature deformation resistance, and low temperature viscoelastic properties of the two WMA were analyzed using a bonding material high and low temperature performance test. By combining the Refatus and Burgers models, the optimal dosage of the two warm mixes (S and G) was determined to be 4.0 % and 0.6 %, respectively. The prediction accuracy of three micromechanical models, including Hashin and Buttlar, for the high temperature performance of mastic was compared through the particle reinforcement theory system. The results showed that the warm mix additives significantly improved the high temperature stability performance of the asphalt, reduced the temperature sensitivity of the asphalt, and the Refatus model parameter a was decreased by 9.15 % and 1.0 % for B-S-4 and B-G-0.6 (denoting 4 % S and 0.6 % G added to the SBS modified asphalt, respectively). The creep deformation of WMA was smaller than that of the asphalt in the original samples, and the warm mix additives effectively improved the low temperature cracking resistance of asphalt. The Buttlar model optimally predicted the high temperature performance in the mastic (71 °C/29 °C correlation coefficient R 2 = 0.991/0.917), and the adsorption of mineral powders with SBS modified asphalt was superior to that of the base asphalt. At the same time, the warming agent had a detrimental effect on the asphalt adsorption. The results provide a theoretical basis for predicting WMA mastic’s multiscale performance and for designing sustainable pavement materials.
To study the evolution of the rheological properties of warm mix asphalt (WMA) and its mastic viscoelastic drive prediction model, different dosages of Sasobit (S) and Evotherm 3G (G) WMA were prepared. The temperature sensitivity, high temperature deformation resistance, and low temperature viscoelastic properties of the two WMA were analyzed using a bonding material high and low temperature performance test. By combining the Refatus and Burgers models, the optimal dosage of the two warm mixes (S and G) was determined to be 4.0 % and 0.6 %, respectively. The prediction accuracy of three micromechanical models, including Hashin and Buttlar, for the high temperature performance of mastic was compared through the particle reinforcement theory system. The results showed that the warm mix additives significantly improved the high temperature stability performance of the asphalt, reduced the temperature sensitivity of the asphalt, and the Refatus model parameter a was decreased by 9.15 % and 1.0 % for B-S-4 and B-G-0.6 (denoting 4 % S and 0.6 % G added to the SBS modified asphalt, respectively). The creep deformation of WMA was smaller than that of the asphalt in the original samples, and the warm mix additives effectively improved the low temperature cracking resistance of asphalt. The Buttlar model optimally predicted the high temperature performance in the mastic (71 °C/29 °C correlation coefficient R 2 = 0.991/0.917), and the adsorption of mineral powders with SBS modified asphalt was superior to that of the base asphalt. At the same time, the warming agent had a detrimental effect on the asphalt adsorption. The results provide a theoretical basis for predicting WMA mastic’s multiscale performance and for designing sustainable pavement materials.
作者机构：
National Engineering Research Center of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha, HN 410114, China;[Liyan Liu] School of Transportation, Changsha University of Science & Technology, Changsha, HN 410114, China;[Shirong Zhou; Zhong Zhou] School of Civil Engineering, Central South University, Changsha, HN 410075, China;[Hao Yang] National Engineering Research Center of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha, HN 410114, China<&wdkj&>School of Transportation, Changsha University of Science & Technology, Changsha, HN 410114, China
通讯机构：
[Shirong Zhou; Zhong Zhou] S;School of Civil Engineering, Central South University, Changsha, HN 410075, China
摘要：
Defects in tunnel linings accelerate structural deterioration, reduce service life, and pose serious safety risks. Existing algorithms for detecting defect signals in ground-penetrating radar (GPR) images often struggle to balance accuracy and efficiency, with limited capacity to extract meaningful features. To address these limitations, this paper proposes a lightweight algorithm, MGD-DETR, for accurate recognition of internal tunnel lining defects, using RT-DETR as the base model. First, a Multi-HGNet backbone feature extraction network is introduced to reduce model size (MS) and enhance dynamic fusion and interaction between feature layers, thereby improving feature extraction. Second, the lightweight convolution module GSConv replaces standard convolution operations to reduce the parameter count. Third, a dual attention module (DAM) is integrated to dynamically adjust spatial and channel feature weights, improving the model’s generalization performance. Five models—RT-DETR, YOLO-LD, YOLOv10, YOLOv11, and SSD—were used for comparative evaluation. Experimental results show that MGD-DETR outperforms the other models across all metrics, achieving a mean average precision (mAP) of 0.834, mean F1 score (mF1) of 0.818, MS of 26.9 M, and frames per second (FPS) of 91.2f/s, enabling fast and accurate recognition of defect signals and facilitate subsequent deployment into tunnel detection mobile devices.
Defects in tunnel linings accelerate structural deterioration, reduce service life, and pose serious safety risks. Existing algorithms for detecting defect signals in ground-penetrating radar (GPR) images often struggle to balance accuracy and efficiency, with limited capacity to extract meaningful features. To address these limitations, this paper proposes a lightweight algorithm, MGD-DETR, for accurate recognition of internal tunnel lining defects, using RT-DETR as the base model. First, a Multi-HGNet backbone feature extraction network is introduced to reduce model size (MS) and enhance dynamic fusion and interaction between feature layers, thereby improving feature extraction. Second, the lightweight convolution module GSConv replaces standard convolution operations to reduce the parameter count. Third, a dual attention module (DAM) is integrated to dynamically adjust spatial and channel feature weights, improving the model’s generalization performance. Five models—RT-DETR, YOLO-LD, YOLOv10, YOLOv11, and SSD—were used for comparative evaluation. Experimental results show that MGD-DETR outperforms the other models across all metrics, achieving a mean average precision (mAP) of 0.834, mean F1 score (mF1) of 0.818, MS of 26.9 M, and frames per second (FPS) of 91.2f/s, enabling fast and accurate recognition of defect signals and facilitate subsequent deployment into tunnel detection mobile devices.
通讯机构：
[Zhou, CJ ] G;Guangzhou Univ, Sch Civil Engn & Transportat, Guangzhou 510006, Peoples R China.
关键词：
urban rail transit ridership;land use;temporal heterogeneity;panel data analysis;transit-oriented development
摘要：
Understanding how land use affects urban rail transit (URT) ridership is essential for facilitating URT usage. While previous studies have explored the way that land use impacts URT ridership, few have figured out how this impact evolves over time. Utilizing URT turnstile and land use data in Beijing, we employed panel data analysis methods to verify the existence of the temporal heterogeneity of the impact and capture this temporal heterogeneity. The results identified time-varying impacts of land use on the URT boarding and alighting trips on weekdays and non-weekdays and also demonstrated the rationality of the mixed effects time-varying coefficient panel data (TVC-P) model in capturing this temporal heterogeneity accurately. The TVC-P model revealed how land use density appealed to URT commuting during weekday morning peak times, and how it triggered the generation of URT commutes during the weekday evening rush hours. The land use diversity promoted URT trips over an extended period on non-weekdays. Additionally, the study identified the time-varying impacts of specific land use on URT ridership. These insights provide both theoretical and empirical support for developing policies and actions that improve the efficiency of transportation systems and foster alignment between land use and transport.
关键词：
Discrete element method;Gap-graded soils;Particle size distribution;Peak strength;Anisotropy;Predictive formula
摘要：
Gap-graded soils, extensively utilized in geotechnical and hydraulic engineering, exhibit diverse strength characteristics governed by their distinctive particle size distribution (PSD). To investigate the influence of PSD on the shear strength of gap-graded soils, this study utilizes the Discrete Element Method (DEM) to reproduce drained conventional triaxial tests of gap-graded soils across a wide range of fine particle content (FC = 1-40%) and particle size ratio (SR = 2.5-6.0). The simulation results reveal that the peak shear strength follows a characteristic unimodal curve versus FC, attaining its maximum value at about FC = 25%. SR governs peak strength through critical FC thresholds: negligible impact at FC < 10%, whereas significant enhancement occurs at FC = 25%. Micromechanical analysis reveals that branch anisotropy evolution controls strength behaviour. Shear strength inversely correlates with peak branch anisotropy as reduced branch anisotropy promotes homogenized contact force distribution. FC and SR collectively regulate macroscopic strength through coupled control of branch anisotropy evolution, where their synergistic interaction governs force chain reorganization and stress distribution homogeneity. Based on these insights, a novel predictive formula for peak strength incorporating both SR and FC were proposed, providing guidance for optimized deployment of gap-graded soils in engineering practice.
关键词：
temperature field;long longitudinal slope;finite element;mechanical response
摘要：
With the rapid increase in traffic volume and the number of heavy-duty vehicles, the load on asphalt pavements has increased significantly. Especially on sections with long longitudinal slopes, the internal stress conditions of asphalt pavement have become even more complex. This study aims to investigate the thermal-mechanical coupling behavior of asphalt pavement structures on long longitudinal slopes under the combined influence of temperature fields and moving loads. A pavement temperature field model was developed based on the climatic conditions of Nanning (AAT: 21.8 °C; Tmax: 37 °C; Tmin: 3 °C; AAP: 1453.4 mm). In addition, a three-dimensional finite element model of asphalt pavement structures on long longitudinal slopes was established using finite element software. Variations in pavement mechanical responses were compared under different vehicle axle loads (100-200 kN), slope gradients (0-5%), braking coefficients (0-0.7), and asphalt mixture layer thicknesses (2-8 cm). The results indicate that the pavement structure exhibits a strong capacity for pressure attenuation, with the middle and lower surface layers showing more pronounced stress reduction-up to 40%-significantly greater than the 6.5% observed in the upper surface layer. As the axle load increases from 100 kN to 200 kN, the internal mechanical responses of the pavement show a linear relationship with load magnitude, with an average increase of approximately 29%. In addition, the internal shearing stress of the pavement is more sensitive to changes in slope and braking coefficient; when the slope increases from 0% to 5% and the braking coefficient increases from 0 to 0.7, the shear stress at the bottom of the upper surface layer increases by 12% and 268%, respectively. This study provides guidance for the design of asphalt pavements on long longitudinal slopes. In future designs, special attention should be given to enhancing the shear strength of the surface layer and improving the interlayer bonding performance. In particular, under conditions of steep slopes and frequent heavy vehicle traffic, the thickness and modulus of the upper surface asphalt mixture may be appropriately increased.
摘要：
As an emerging environmentally friendly solid waste-based composite foam lightweight soil, saponified slag fly ash (SS-FA) foam lightweight soil has a wide range of application prospects in road engineering. In this paper, the dynamic characteristics of SS-FA foam light soil material were investigated. Dynamic triaxial tests under different cyclic loading conditions were designed to analyze the variation rules of dynamic elastic modulus and damping ratio. The results showed that the stress-strain curve of SS-FA foam lightweight soil can be divided into three stages: elastic stage, plateau stage, and stress yielding stage. Under cyclic dynamic load, with the increase of dynamic stress amplitude, the dynamic elastic modulus of 400–700 kg/m3 samples gradually increased to the maximum, reaching 235.24 MPa, 324.54 MPa, 356.45 MPa, 379.67 MPa, respectively. The damping ratio, on the other hand, shows a tendency to first decrease and then slowly increase to stabilize. The dynamic elastic modulus is positively correlated with density grade, confining pressure and loading frequency. The damping ratio decreases with the increase of density grade and loading frequency, and increases with the increase of confining pressure. The electron microscope test was designed and image processing and data statistics were carried out. Through the grey correlation analysis, the correlation degree between the microstructure parameters of SS-FA foamed lightweight soil and the macroscopic mechanical properties is basically above 0.6, indicating that the two have a significant correlation. A normalized prediction formula model between the dynamic elastic modulus of materials and the conditional parameters was established. The R 2 of the linear fitting of the predicted value is 0.964, indicating that the prediction model has a high degree of fitting and a good prediction effect. The research results revealed the dynamic mechanical properties of foamed lightweight soil, and provided a reference for the application of SS-FA foamed lightweight soil in subgrade engineering.
As an emerging environmentally friendly solid waste-based composite foam lightweight soil, saponified slag fly ash (SS-FA) foam lightweight soil has a wide range of application prospects in road engineering. In this paper, the dynamic characteristics of SS-FA foam light soil material were investigated. Dynamic triaxial tests under different cyclic loading conditions were designed to analyze the variation rules of dynamic elastic modulus and damping ratio. The results showed that the stress-strain curve of SS-FA foam lightweight soil can be divided into three stages: elastic stage, plateau stage, and stress yielding stage. Under cyclic dynamic load, with the increase of dynamic stress amplitude, the dynamic elastic modulus of 400–700 kg/m3 samples gradually increased to the maximum, reaching 235.24 MPa, 324.54 MPa, 356.45 MPa, 379.67 MPa, respectively. The damping ratio, on the other hand, shows a tendency to first decrease and then slowly increase to stabilize. The dynamic elastic modulus is positively correlated with density grade, confining pressure and loading frequency. The damping ratio decreases with the increase of density grade and loading frequency, and increases with the increase of confining pressure. The electron microscope test was designed and image processing and data statistics were carried out. Through the grey correlation analysis, the correlation degree between the microstructure parameters of SS-FA foamed lightweight soil and the macroscopic mechanical properties is basically above 0.6, indicating that the two have a significant correlation. A normalized prediction formula model between the dynamic elastic modulus of materials and the conditional parameters was established. The R 2 of the linear fitting of the predicted value is 0.964, indicating that the prediction model has a high degree of fitting and a good prediction effect. The research results revealed the dynamic mechanical properties of foamed lightweight soil, and provided a reference for the application of SS-FA foamed lightweight soil in subgrade engineering.
关键词：
Polyvinyl alcohol fiber reinforced concrete;analysis of the synergistic effects of PCEs and HPMC;performance testing and molecular dynamics simulation;characterization of mechanical properties and fiber dispersion characteristics;multi-site adsorption and competitive adsorption effects
摘要：
PCEs and HPMC are vital to PVA-FRC, where imbalance causes bleeding and viscosity issues, affecting fiber distribution and performance. This study investigates the synergistic mechanisms of PCEs and HPMC on fiber dispersion and mechanical properties through macroscopic experiments and microscopic simulations. Experimental results show that an increase in HPMC dosage or a decrease in PCE dosage reduces fiber uniformity. The mechanical properties of PVA-FRC are influenced by multiple factors, leading to complex non-linear trends. The best performance is achieved when PCE is 0.4% of cement mass and HPMC does not exceed 0.1%. Molecular dynamics simulations show that PCEs and HPMC influence the hydration behavior of C.S.H. gel, transforming it from a single-point adsorption mode to a multi-point adsorption mode. PCEs promote fluidity by displacing water molecules from the active sites, while HPMC forms charge transfer complexes with C.S.H. gel, preventing gel particle aggregation and improving the slurry's viscosity and stability.
摘要：
The occurrence of top-down (TD) cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service. A coupled simulation model integrating the finite difference method (FDM) and discrete element method (DEM) was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack. The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road. Finally, an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress, vertical shear stress, and vertical compressive stress. The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface, while the longitudinal development of TD crack has minimal impact. This phenomenon may result in more severe fatigue failure on the middle surface. With the vertical and longitudinal development of TD crack, the vertical shear stress and compressive stress show obvious "two-stage" characteristics. When the crack's vertical length reaches 40 mm, there is a sharp increase in stress on the upper surface. As the crack continues to propagate vertically, the growth of stress on the upper surface becomes negligible, while the stress in the middle and lower layers increased significantly. Conversely, for longitudinal development of TD crack, any changes in stress are insignificant when their length is less than 180 mm; however, as they continue to develop longitudinally beyond this threshold, there is a sharp increase in stress levels. These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.
The occurrence of top-down (TD) cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service. A coupled simulation model integrating the finite difference method (FDM) and discrete element method (DEM) was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack. The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road. Finally, an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress, vertical shear stress, and vertical compressive stress. The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface, while the longitudinal development of TD crack has minimal impact. This phenomenon may result in more severe fatigue failure on the middle surface. With the vertical and longitudinal development of TD crack, the vertical shear stress and compressive stress show obvious "two-stage" characteristics. When the crack's vertical length reaches 40 mm, there is a sharp increase in stress on the upper surface. As the crack continues to propagate vertically, the growth of stress on the upper surface becomes negligible, while the stress in the middle and lower layers increased significantly. Conversely, for longitudinal development of TD crack, any changes in stress are insignificant when their length is less than 180 mm; however, as they continue to develop longitudinally beyond this threshold, there is a sharp increase in stress levels. These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.
期刊：
Frontiers in Materials,2025年12:1656467 ISSN：2296-8016
通讯作者：
Jin, X
作者机构：
[Liu, Jinguo; Xia, Chengdong; Liu, Duyang; Ling, Yumeng; Huang, Bin; Liu, Bowen; Jin, Xin; Liu, Chenxi; Wang, Dikuan] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha, Peoples R China.;[Huang, Bin] Hunan Prov Expressway Grp Co Ltd, Changsha, Peoples R China.;[Xiao, Ge] Modern Investment Co Ltd, Changsha, Peoples R China.;[Xia, Chengdong] Hong Kong Polytech Univ, Dept Civil & Environm Engn, Hong Kong, Peoples R China.;[Xia, Chengdong] Xiangjiang Lab, Changsha, Peoples R China.
通讯机构：
[Jin, X ] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha, Peoples R China.
关键词：
Ultra-thin overlay;Chemically toughened asphalt;Loading rate;Strength response;Rate sensitivity;Unified strength model
摘要：
To enhance the mechanical performance of ultra-thin asphalt overlays subjected to heavy traffic and harsh environmental conditions, this study developed a high-performance asphalt mixture (SMA-8) incorporating a chemically toughened modified binder, specifically designed for ultra-thin overlay applications. The strength response of this mixture under varying loading rates was systematically evaluated through direct tensile, indirect tensile, and unconfined compressive tests, with emphasis on rate-dependent behavior and strength evolution across different stress states. Experimental results revealed that all strength indices increased with loading rate following power-law trends. Among them, the indirect tensile strength exhibited the highest sensitivity to loading rate, while compressive strength demonstrated the highest overall magnitude. Using Mohr-Coulomb theory, cohesion and internal friction angle were derived from tensile and compressive test results under different loading conditions. Cohesion increased significantly with loading rate, whereas the internal friction angle showed a non-monotonic variation, suggesting complex interfacial failure mechanisms. A unified strength model was proposed by establishing normalized conversion relationships among the three loading modes, providing a generalized framework for strength characterization of ultra-thin overlay materials. This study offers both theoretical insights and practical guidance for the mechanical design, strength evaluation, and engineering application of chemically modified high-performance ultra-thin overlays.
期刊：
Transportation Safety and Environment,2025年7(2) ISSN：2631-6765
通讯作者：
Jian Xiang
作者机构：
[Wang, Yi] School of Hydraulic and Ocean Engineering, Changsha University of Science & Technology , Changsha 410114, Hunan , China;[Xiang, Jian; Pan, Junliang; Wang, Jie; Chen, Tao] School of Transportation, Changsha University of Science & Technology , Changsha 410114, Hunan , China;Hunan Communications Research Institute Co., Ltd. , Changsha 410114, Hunan , China;[Wang, Hao] School of Transportation, Changsha University of Science & Technology , Changsha 410114, Hunan , China<&wdkj&>Hunan Communications Research Institute Co., Ltd. , Changsha 410114, Hunan , China
通讯机构：
[Jian Xiang] S;School of Transportation, Changsha University of Science & Technology , Changsha 410114, Hunan , China
摘要：
This study introduces a multi-area cooperative merging control strategy to enhance the safety and efficiency of connected and autonomous vehicles (CAVs) at freeway merging areas with multiple mainline lanes and a dual-lane ramp. The strategy integrates lane changing in advance tactics for upstream mainline vehicles and speed regulation for ramp vehicles into a structured control framework. This framework comprises distinct areas for proactive mainline lane changing in advance, ramp speed regulation and cooperative merging. For the mainline lane-changing area, we propose a strategy that relies on maintaining a minimum safety distance and optimizing speed benefits, thereby enhancing merging opportunities for ramp vehicles and balancing downstream traffic flows. In the ramp speed regulation area, a vehicular speed control model is established, utilizing a ‘FIFO rule’ based on the vehicles’ arrival times at the acceleration lane start, coupled with a virtual platoon concept to synchronize and optimize platoon speeds for efficient travel on ramps. In the cooperative merging area, vehicle trajectories on the mainline and ramp are optimized in a rolling horizon manner, facilitating seamless integration of ramp vehicles into the mainline. Simulation results indicate that our proposed cooperative control method significantly surpasses uncontrolled and trajectory-only optimization approaches in control efficiency across varying traffic demands. This method demonstrates notable advancements in average speed, delay reduction and fewer stops, with minimized fluctuations and increased control stability. Additionally, the cooperative control approach demonstrates superior adaptability across different numbers of ramp lanes, with scenarios involving dual-lane ramps exhibiting a more pronounced advantage.
摘要：
Objective This study aims to address the limitations of using historical crash data and trajectory data for crash and conflict identification. Specifically, it focuses on enhancing real-time conflict identification by investigating the influence of traffic flow state variables and their interactions on conflicts.
This study aims to address the limitations of using historical crash data and trajectory data for crash and conflict identification. Specifically, it focuses on enhancing real-time conflict identification by investigating the influence of traffic flow state variables and their interactions on conflicts.
Methods Vehicle trajectory data from HighD were processed, allowing extraction of traffic flow state and corresponding conflict during a specific time interval (10 s). Logistic regression models were further used to verify the impact of variables, including interaction terms, on the conflicts for different lane categories (inner, middle, and outer lanes). Additionally, machine learning techniques were employed to compare conflict identification performance including or excluding variable interactions.
Vehicle trajectory data from HighD were processed, allowing extraction of traffic flow state and corresponding conflict during a specific time interval (10 s). Logistic regression models were further used to verify the impact of variables, including interaction terms, on the conflicts for different lane categories (inner, middle, and outer lanes). Additionally, machine learning techniques were employed to compare conflict identification performance including or excluding variable interactions.
Results The interaction terms of the traffic flow state variables have significant effects on the conflicts for different categories of lanes. It is therefore essential to consider both the individual effects of traffic variables and their interaction effects to analyze conflict risk. Considering variable interactions leads to improved conflict identification accuracy and reduced identification error rates in comparison to the condition where interaction items are not taken into account.
The interaction terms of the traffic flow state variables have significant effects on the conflicts for different categories of lanes. It is therefore essential to consider both the individual effects of traffic variables and their interaction effects to analyze conflict risk. Considering variable interactions leads to improved conflict identification accuracy and reduced identification error rates in comparison to the condition where interaction items are not taken into account.
Conclusions The interaction terms of traffic flow state variables significantly affect and enhance conflict identification, improving accuracy and reducing error rates. These findings contribute to advancing the high-precision identification of real-time conflict identification, with implications for improving road safety measures.
The interaction terms of traffic flow state variables significantly affect and enhance conflict identification, improving accuracy and reducing error rates. These findings contribute to advancing the high-precision identification of real-time conflict identification, with implications for improving road safety measures.
期刊：
Environment, Development and Sustainability,2025年:1-31 ISSN：1387-585X
通讯作者：
Zhai, Z
作者机构：
[Gao, Shirong; Zhai, Zhao] Changsha Univ Sci & Technol, Sch Transportat, 960 South Wanjiali Rd, Changsha, Peoples R China.;[Gao, Shirong; Zhai, Zhao] Changsha Univ Sci & Technol, Hunan Int Sci & Technol Innovat Cooperat Base Adv, Changsha 410114, Hunan, Peoples R China.;[Shan, Ming] Cent South Univ, Sch Civil Engn, 68 South Shaoshan Rd, Changsha, Peoples R China.
通讯机构：
[Zhai, Z ] C;Changsha Univ Sci & Technol, Sch Transportat, 960 South Wanjiali Rd, Changsha, Peoples R China.;Changsha Univ Sci & Technol, Hunan Int Sci & Technol Innovat Cooperat Base Adv, Changsha 410114, Hunan, Peoples R China.
关键词：
Environmentally responsible behavior;Stimulus-Organism-Response;Institutional theory;Theory of planned behavior
摘要：
In the context of sustainable development, environmental responsibility behavior in megaprojects has become critical. However, the comprehensive interplay of internal and external factors influencing contractors' environmental responsibility behavior remains underexplored. This study integrates institutional theory and the theory of planned behavior into the Stimulus-Organism-Response framework to construct a theoretical model. Through this framework, the study investigates the driving factors and their mechanisms affecting the environmental responsibility behavior of megaproject contractors. A total of 256 questionnaires were collected from megaproject contractors, and partial least squares structural equation modeling was used for analysis. Results show that coercive, mimetic, and normative pressures positively influence contractors' attitudes, subjective norms, and perceived behavioral control. These internal factors, in turn, positively affect contractors' environmentally responsible behavior intention and ultimately their actual behavior. Furthermore, coercive and mimetic pressures positively impact contractors' environmental responsibility behavior, and this relationship is enhanced by corporate green culture. Normative pressure also positively affects environmental responsibility behavior, with this effect strengthened by a strong moral identity. These findings provide theoretical and practical guidance for enhancing contractors' environmental awareness and promoting sustainable development of megaprojects.
关键词：
Configuration;FsQCA;NCA;Transportation system resilience
摘要：
With the deep integration of digital technology and transportion system, building a new transportion system with high resilience has become a key issue to ensure sustainable urban development. It not only improves the safety resilience of cities, but also effectively alleviates their traffic congestion, thereby promoting economic prosperity and sustainable urban development. In the context of digital ecology, this study combined Necessary Condition Analysis (NCA) and Fuzzy Set Qualitative Comparative Analysis (fsQCA) to analyze the multifaceted paths of five digital factors to build the transportation system resilience. The findings reveal that achieving higher transportation system resilience requires a comprehensive consideration of multiple factors rather than relying solely on a single condition; there are three paths to build the resilience of transportation system, i.e., digital foundation-economically-enabled, digital foundation-socially-enabled and digital empowerment-multiple-enabled paths; among them, digital foundation, digital economy and digital society play more critical roles in building the transportation system resilience. This study can provide a reference for these cities with low transportation system resilience to choose appropriate paths to effectively build their transportation system resilience based on their unique conditions and locally-tailored policies.
摘要：
Soft soil poses significant challenges in highway engineering due to its low strength and high compressibility. This study proposes using xanthan gum biopolymer as an environmentally friendly agent to improve the mechanical behavior of soft soil. Laboratory tests were conducted to analyze the unconfined compressive strength (UCS) and compressibility of xanthan-gum-stabilized soft soil under dry-wet cycles. Physicochemical analysis was performed to examine the pH value, electrical conductivity, and total dissolved solids (TDS) of the stabilized soil. Additionally, microscopic tests were performed to investigate the stabilization mechanism. The results demonstrate that the UCS of the stabilized soil consistently increases with curing age while it decreases under dry-wet cycles. Moreover, the UCS, durability, and modulus of compressibility of the stabilized soil initially increase significantly and then slightly decrease with increasing xanthan gum dosage. At the optimal xanthan gum dosage (1.5%), the UCS reaches 376.3 kPa at 28 d of curing and drops by only 24.1% even after ten dry-wet cycles, and the modulus of compressibility is enhanced to 37.13 MPa; meanwhile, the corresponding compression index and coefficient of compressibility are reduced to 0.082 and 0.061 MPa-1, respectively, indicating satisfactory performance of the stabilized soil as highway foundation material. The stabilization mechanism of xanthan-gum-treated soft soil primarily involves the bonding and filling effects of the hydrogel resulting from the hydration of xanthan gum. These findings suggest that xanthan gum is a promising and effective stabilizing agent for soft soil as it can significantly reduce soil water content and void ratio.
摘要：
This paper proposes a novel hierarchical controller for connected truck platoons. To this end, the predecessor following topology is used to characterize the communication connectivity between connected trucks. Then, a longitudinal efficient controller consisting of upper-level and lower-level controllers is proposed. In particular, the upper-level controller is designed based on the kinematic model to handle the car-following interactions between connected trucks and delays in communication and input. The lower-level controller comprises a feedforward and a feedback control law. The feedforward control law converts the desired acceleration from the upper-level controller into the vehicle throttle or braking pressure using the inverse dynamic model, while the feedback control law compensates for the control error caused by unknown vehicle parameters. In addition, in the linear region, the internal stability is analyzed based on the second-order kinematic model using s-domain analysis and linearization method, respectively. Then, the string stability is proved. The influence of parameters on the stability performance is extensively discussed using the stability diagram. Finally, the feasibility of the proposed controller is verified via co-simulations in PreScan and TruckSim, in terms of acceleration, velocity, and spacing error profiles.
摘要：
Hot mix asphalt mixture is considered the ideal approach to reuse waste plastics in high-value applications because of its very high amount of usage in highway construction. However, the differences in polarity and density between polymers and asphalt lead to polymer coalescence and therefore the poor storage stability of modified asphalt. These challenges are exalted when recycling commingled plastics. This study introduced an innovative compatibilization strategy and mechanism for co-stabilizing commingled plastics and pyrolyzed rubber in asphalt. Commingled plastics were first grafted with maleic anhydride for surface activation, followed by reactive kneading with pyrolyzed rubber and crosslinking agent to form an integrated thermoplastic elastomer (ITPE) for asphalt modification. The mechanical, thermal, and interfacial behaviors of the ITPE were evaluated through tensile testing, thermogravimetric analysis, and scanning electron microscopy. The storage stability and rheological properties of the modified binder blends were evaluated through the cigar tube test and dynamic shear rheometer testing. Results demonstrated a successful formation of imide bonds in the ITPE, which can improve the strength, ductility, and thermal stability of rubber-plastic composites. Appropriate utilization of crosslinking agents can improve both rutting and fatigue resistance of ITPE-modified asphalt with good storage stability because of the co-existence of rigid plastic and soft rubbery regimes and the formation of a crosslink network. However, excessive content of crosslinker led to severe phase separation and reduced storage stability of modified binder blends. Extra crosslinker tended to float in asphalt because of its low density and caused an excessive formation of the crosslink network in the top section of the asphalt.
摘要：
Connected vehicles (CVs) serve as an important connection from human-driven vehicles (HDVs) to pure connected autonomous vehicles, whose main function is to improve driver’s operation combined with driver assistance systems (DAS). By utilizing information shared on CVs, DAS is capable of automatically calculating and analyzing safe and efficient driving behaviors for drivers. However, drivers may operate by combining their personal thoughts with shared recommendation of DAS, which will usually result in a response time-delay. Therefore, the paper presents an innovative feedback control strategy that considers the driver’s visual angle response time-delay for the two-dimensional two-lane car-following model (TDTLCFM) combined with compliance rate of CVs drivers to DAS to optimize and improve DAS. Through the linear analysis and Hopf bifurcation analysis to obtain the stability conditions and equilibrium points of the traffic flow. And then designing the feedback controller to suppress traffic instability so as to suppress traffic bifurcation caused by driver’s response time-delay. Finally, numerical simulation was conducted on 100 vehicles, and the simulation results show that the controller can effectively suppress traffic congestion without changing the equilibrium point, significantly improving traffic efficiency and stability. At the same time, numerical simulations of heterogeneous traffic flow composed of HDVs and CVs indicate that the stability of mixed flows varies with the market penetration rate of CVs, the higher the market penetration rate, the stronger the anti-interference ability of the mixed flow.
Connected vehicles (CVs) serve as an important connection from human-driven vehicles (HDVs) to pure connected autonomous vehicles, whose main function is to improve driver’s operation combined with driver assistance systems (DAS). By utilizing information shared on CVs, DAS is capable of automatically calculating and analyzing safe and efficient driving behaviors for drivers. However, drivers may operate by combining their personal thoughts with shared recommendation of DAS, which will usually result in a response time-delay. Therefore, the paper presents an innovative feedback control strategy that considers the driver’s visual angle response time-delay for the two-dimensional two-lane car-following model (TDTLCFM) combined with compliance rate of CVs drivers to DAS to optimize and improve DAS. Through the linear analysis and Hopf bifurcation analysis to obtain the stability conditions and equilibrium points of the traffic flow. And then designing the feedback controller to suppress traffic instability so as to suppress traffic bifurcation caused by driver’s response time-delay. Finally, numerical simulation was conducted on 100 vehicles, and the simulation results show that the controller can effectively suppress traffic congestion without changing the equilibrium point, significantly improving traffic efficiency and stability. At the same time, numerical simulations of heterogeneous traffic flow composed of HDVs and CVs indicate that the stability of mixed flows varies with the market penetration rate of CVs, the higher the market penetration rate, the stronger the anti-interference ability of the mixed flow.
摘要：
As an essential component of China's comprehensive transportation network, freeways play an irreplaceable role in promoting regional economic integration, improving logistics efficiency, and serving public travel. However, the development of freeways faces challenges such as the underutilization of road resources, significant financial pressure for construction and maintenance, and imbalanced revenue and expenditure leading to heavy debt burdens, which severely impact the sustainable development of freeways. Optimizing freeway toll rates is an effective measure to alleviate these issues, playing a crucial role in enhancing the operational efficiency of the road network and increasing the revenue of freeway operating enterprises. Existing studies have focused on finding the optimal toll rates for freeways based on bi-level programming models, neglecting the dynamic relationships among individual travel behavior preferences, toll rates, travel demand, and toll revenue. Grounded in bounded rationality theory, the research employs microscopic traffic simulation technology to analyze the dynamic relationships among freeway toll rates, travel demand, and toll revenue. The results confirm that travel demand decreases as toll rates increase, while toll revenue exhibits asymmetric "synchronization" and "asynchronization" phases, peaking at CYN 58.9 thousand (USD 8246) when the toll rate reaches CYN 0.45/km (USD 0.06/km). Additionally, users' rationality levels significantly affect the stabilization time of toll revenue, and the speed difference between freeways and parallel roads demonstrates a threshold effect on travel demand and revenue. These findings provide theoretical and technical support for optimizing freeway toll strategies, enhancing operational efficiency, and promoting sustainable transportation development.
关键词：
Asphalt fine aggregate matrix;Nano-CT scanning;Blue light scanning;Aggregate model;Specific surface area
摘要：
This research aims to clarify uncertainties in asphalt and filler proportions for Fine Aggregate Matrix (FAM) mix design and to determine the Nominal Maximum Aggregate Size (NMAS). The three-dimensional blue light scanning apparatus and high-precision balances were utilized to generate an aggregate model library encompassing four size ranges. The aggregate model library facilitated investigating the aggregates' distribution of various physical parameters. The model proposed using the short and middle axes of the minimum bounding box as particle size indicators. The aggregate particle size distribution conformed to a Gaussian pattern, and a power function relationship was identified between specific surface area and particle size. Nano-CT and image segmentation techniques were used to determine the thicknesses of the pure asphalt layer and asphalt mastic on aggregate surfaces. These data and aggregate distribution models helped calculate FAM mix proportions for NMAS of 4.75 mm, 2.36 mm, and 1.18 mm in AC-13, OGFC-13, and SMA-13, respectively. FAM beamlet specimens were created using rotary compaction and precision cutting, then tested with the Meso Scale Under Microscope Universal Load Frame (μTS) to observe strain behavior under three-point bending and uniaxial tension. The strain coefficient of variation was proposed to assess material homogeneity. The study found cohesive cracking in FAM with 1.18 mm NMAS and adhesive cracking at sizes above 2.36 mm. FAM with 1.18 mm NMAS is recommended as a dispersive medium, optimizing its function as a matrix material.
This research aims to clarify uncertainties in asphalt and filler proportions for Fine Aggregate Matrix (FAM) mix design and to determine the Nominal Maximum Aggregate Size (NMAS). The three-dimensional blue light scanning apparatus and high-precision balances were utilized to generate an aggregate model library encompassing four size ranges. The aggregate model library facilitated investigating the aggregates' distribution of various physical parameters. The model proposed using the short and middle axes of the minimum bounding box as particle size indicators. The aggregate particle size distribution conformed to a Gaussian pattern, and a power function relationship was identified between specific surface area and particle size. Nano-CT and image segmentation techniques were used to determine the thicknesses of the pure asphalt layer and asphalt mastic on aggregate surfaces. These data and aggregate distribution models helped calculate FAM mix proportions for NMAS of 4.75 mm, 2.36 mm, and 1.18 mm in AC-13, OGFC-13, and SMA-13, respectively. FAM beamlet specimens were created using rotary compaction and precision cutting, then tested with the Meso Scale Under Microscope Universal Load Frame (μTS) to observe strain behavior under three-point bending and uniaxial tension. The strain coefficient of variation was proposed to assess material homogeneity. The study found cohesive cracking in FAM with 1.18 mm NMAS and adhesive cracking at sizes above 2.36 mm. FAM with 1.18 mm NMAS is recommended as a dispersive medium, optimizing its function as a matrix material.
作者机构：
[Sun, Wenke; Sun, WK; Wen, Zhiqiang] Univ Chinese Acad Sci, Chinese Acad Sci, Coll Earth & Planetary Sci, Key Lab Earth Syst Numer Modeling & Applicat, Beijing 100049, Peoples R China.;[Rao, Weilong] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410114, Peoples R China.
通讯机构：
[Sun, WK ] U;Univ Chinese Acad Sci, Chinese Acad Sci, Coll Earth & Planetary Sci, Key Lab Earth Syst Numer Modeling & Applicat, Beijing 100049, Peoples R China.
关键词：
Loading of the Earth;Satellite gravity;Time variable gravity;Asia;Moho depth
摘要：
Active tectonic movements and surface deformation are observed in the eastern Tibetan Plateau. Understanding variations in crustal thickness and the deep Moho interface is crucial for elucidating the expansion of the Tibetan Plateau. This study utilizes InSAR to derive vertical surface deformation and applies loading corrections based on Green's function method. Additionally, satellite gravity data are used to separate hydrological and tectonic signals to infer changes in the Moho interface. Our results indicate that the regionally averaged loading effects, estimated using localized Green's functions, account for approximately 16.5 per cent of the InSAR-derived vertical displacement field. This contribution exhibits significant spatial variability, exceeding 100 per cent in regions with strong hydrological activity. The loading calculation is highly sensitive to Earth model: the relative difference between the load displacement obtained using the local Green's function and that obtained with an average Green's function reaches 48.2 per cent. After applying loading corrections, a more accurate Moho uplift rate of |$- $| 8.2 ± 3.1 mm a −1 is obtained. The findings support the conclusion that the Moho interface rises in the southern region of the study area, with crustal thinning, while the Moho surface sinks in the northern region, with crustal thickening.
