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.
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.
摘要：
In order to investigate the influence of the coexistence of clay and silt on the compression characteristics of sand, one-dimensional compression consolidation tests were carried out on reconstituted saturated sand-silt-clay mixtures with a constant initial void ratio, and the effects of fines content (FC) and clay-silt ratio (CS) on the compression characteristics of mixed soils were studied. The mechanism of the experimental results was additionally explained from a microscopic perspective. The test results show that: the compressibility of mixed soil increased with the increase in FC; the compressibility change rule of mixed soils with different CS is consistent under the same FC; the influence of CS on the e-lgp (the void ratio (e) versus logarithm of the pressure (p)) curve of mixed soil is inconsistent when FC is different: when FC = 3%, the compressibility of mixed soil decreased with the increase in CS; when FC = 7% and 10%, the compressibility of mixed soil gradually increased with the increase in CS; when FC = 5%, the compressibility of mixed soil did not show an obvious changing law with the increase in CS, and the compressibility of the specimen with FC = 5%-CS = 1 (FC = 5%, CS = 1) was the largest; when CS was same, the difference between e-lgp curves of mixed soil with different FC increased with the increase in CS. The compression model of sand-silt-clay mixtures was established, which can consider the effects of FC and CS. The reliability and applicability of the proposed model were verified by combining the experimental results of this paper and the test data of sand-clay mixture and sand-silt mixture in other literature.
关键词：
sustainable transportation;freeway crash;injury severity;interactive effect;random parameters logit model
摘要：
Freeway transportation safety issues have attracted public concern in China for decades. This study aims to identify the factors influencing the injury severity of freeway crashes and to quantify their effects on the likelihood of various crash severity levels, with consideration of heterogeneity and interactions. The empirical analysis is based on three years of crash data from two mountainous freeways in Guangdong, China, covering the years of 2021 to 2023. A random parameters logit model with interaction terms is developed for the analysis. Goodness-of-fit indicators reveal that accommodating the interactive effects can significantly improve model fit performance. The estimation results of the parameters and marginal effects indicate that the factors related to vehicle type, time of day, crash season and cause, 3D curvature, and traffic volume have significant effects on crash severity. Notably, interactive effects are revealed between spring and evening, autumn and fixed objects, and non-local vehicles and improper driving. According to the findings, some countermeasures on safety education, traffic management, and freeway design are provided for preventing freeway crash injury, which is helpful for the development of sustainable transportation systems.
通讯机构：
[Hao, W ] C;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410114, Hunan, Peoples R China.
关键词：
Reliability;Stability analysis;Numerical stability;Thermal stability;Autonomous vehicles;Connected vehicles;Roads;Mathematical models;Pricing;Electronic mail;Connected and autonomous vehicles;travel time reliability;mixed traffic flow
摘要：
Existing studies on traffic flow stability primarily focused on local stability, with little attention given to its extension to the network level, known as network stability. In this paper, a reliability-based equilibrium model in a mixed traffic network including human-driven vehicles and connected and autonomous vehicles is developed to analyze the impact of connected and autonomous vehicles on traffic flow stability. The basic characteristics of the model are first examined on a small network, demonstrating the non-uniqueness of the link flow in the user equilibrium pattern. Then, the model is extended to the case of a general network with Variational Inequality (VI) equations. In addition, a two-level optimization strategy is developed by incorporating the pricing and quantity control strategies to the reliability model. Numerical examples are conducted based on Sioux Falls networks to examine the performance of the proposed models.
期刊：
Resources, Conservation and Recycling,2025年215:108096 ISSN：0921-3449
通讯作者：
Liu, B
作者机构：
[Liu, Bin; Pan, Wei; Liu, B; Yu, Cong] Univ Hong Kong, Dept Civil Engn, Hong Kong 999077, Peoples R China.;[Liu, Bin; Liu, B; Li, Jingjing] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Dept Engn Management, Changsha 410114, Peoples R China.;[Kumar, Pankaj] Inst Global Environm Strategies, Hayama 2400115, Japan.;[Chen, Yifan] Zhejiang Univ Water Resources & Elect Power, Coll Water Conservancy & Environm Engn, Hangzhou 310018, Peoples R China.
通讯机构：
[Liu, B ] U;Univ Hong Kong, Dept Civil Engn, Hong Kong 999077, Peoples R China.;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Dept Engn Management, Changsha 410114, Peoples R China.
关键词：
Sustainable development;Water resilience;Nature-society dual water cycle;Climate change;Spatiotemporal analysis;China
摘要：
Water cycle resilience represents a vital part of sustainable water resources management for a region with severe water vulnerability issues. However, despite their importance, a current lack of systematic monitoring mechanisms has contributed to an insufficient grasp of their distribution in relation to water resources management practices, as well as their vulnerability to climate change and human impacts. This study develops a nature-society water cycle resilience index that integrates recover and supplement to water vulnerability, which is applied in the case study of China. The results indicate that the comprehensive level of water cycle resilience in China has been constantly improving in the past two decades, whilst varies significantly among provinces in water resources management performance and serious vulnerability issues. This study provides useful references for countries or large-scale regions around the world to promote resilience and sustainability in water resources planning and policy.
Water cycle resilience represents a vital part of sustainable water resources management for a region with severe water vulnerability issues. However, despite their importance, a current lack of systematic monitoring mechanisms has contributed to an insufficient grasp of their distribution in relation to water resources management practices, as well as their vulnerability to climate change and human impacts. This study develops a nature-society water cycle resilience index that integrates recover and supplement to water vulnerability, which is applied in the case study of China. The results indicate that the comprehensive level of water cycle resilience in China has been constantly improving in the past two decades, whilst varies significantly among provinces in water resources management performance and serious vulnerability issues. This study provides useful references for countries or large-scale regions around the world to promote resilience and sustainability in water resources planning and policy.
作者：
Zhang, Min;Zhao, Ya Nan;Wang, Chenxi;Jin, Duo;Chen, Qi
期刊：
Frontiers in Built Environment,2025年11:1670013 ISSN：2297-3362
作者机构：
[Zhang, Min; Wang, Chenxi; Jin, Duo] Mechanization Engineering Co. Ltd., China Railway No. 5 Engineering Group Co., Ltd., Hengyang, China;[Zhao, Ya Nan; Chen, Qi] School of Transportation, Changsha University of Science and Technology, Changsha, China
摘要：
In order to improve the pavement performance and toughness of foam asphalt cold recycled mixture (FACRM), the effects of lignin fiber on the pavement performance of FACRM at 0%, 0.3%, 0.6% and 0.9% dosage (relative to foam asphalt cold recycled mixtures) were investigated. Through the high temperature rutting, semi-circular bending and freeze-thaw splitting tests, the influence of different fiber dosage on the performance of FACRM was investigated, and the microscopic morphology of the fiber on the FACRM damage interface was observed by scanning electron microscope (SEM). The results show that: with the increase of lignin fiber dosage, the maximum dry density of FACRM shows a decreasing trend, the optimum moisture content and the optimum asphalt content gradually increase; dynamic stability, fracture energy and tensile strength ratio (TSR) show a pattern of change that first increases and then decreases; the fiber enhancement mechanism of FACRM pavement performance is that its dispersion of the bridge in the mixture to form the three-dimensional network structure plays the role of reinforcement. Comprehensive lignin fiber on the recycled mixture pavement performance and microscopic morphology of the results, the recommended use of its dosage of 0.3%.
摘要：
The influence mechanism of steel slag as coarse aggregate on the performance of asphalt mixture is not clear. This study starts from the influence of steel slag replacing limestone on the interaction between asphalt and aggregate interface. The interlayer device of the DSR test was improved, and steel slag-asphalt-steel slag (SAS), limestone-asphalt-steel slag (LAS), and limestone-asphalt-limestone (LAL) interlayers were constructed, in which LAS and SAS characterize the partial or total replacement of steel slag for limestone, respectively. The rheological behavior and uniaxial tensile failure characteristics of different interlayer systems were studied. The effect of steel slag replacing limestone on the interfacial interaction was characterized by the evolution of interfacial asphalt performance. The results showed that the influence of temperature and frequency on the complex shear modulus G* was greater than that of lithology and film thickness. Steel slag instead of limestone could increase the G* of interfacial asphalt. The fatigue resistance of interface asphalt gradually increased with the increase of temperature, and the fatigue performance of LAS and SAS interlayer interface asphalt formed by steel slag instead of limestone showed differences. Replacing limestone with steel slag could improve the long-term relaxation ability of interfacial asphalt. The substitution of steel slag for limestone had no negative effect on the tensile properties of interfacial asphalt, and the effect of temperature and film thickness on strength was more obvious than that of loading rate. The research results provided scientific guidance for promoting the resource utilization of steel slag.
The influence mechanism of steel slag as coarse aggregate on the performance of asphalt mixture is not clear. This study starts from the influence of steel slag replacing limestone on the interaction between asphalt and aggregate interface. The interlayer device of the DSR test was improved, and steel slag-asphalt-steel slag (SAS), limestone-asphalt-steel slag (LAS), and limestone-asphalt-limestone (LAL) interlayers were constructed, in which LAS and SAS characterize the partial or total replacement of steel slag for limestone, respectively. The rheological behavior and uniaxial tensile failure characteristics of different interlayer systems were studied. The effect of steel slag replacing limestone on the interfacial interaction was characterized by the evolution of interfacial asphalt performance. The results showed that the influence of temperature and frequency on the complex shear modulus G* was greater than that of lithology and film thickness. Steel slag instead of limestone could increase the G* of interfacial asphalt. The fatigue resistance of interface asphalt gradually increased with the increase of temperature, and the fatigue performance of LAS and SAS interlayer interface asphalt formed by steel slag instead of limestone showed differences. Replacing limestone with steel slag could improve the long-term relaxation ability of interfacial asphalt. The substitution of steel slag for limestone had no negative effect on the tensile properties of interfacial asphalt, and the effect of temperature and film thickness on strength was more obvious than that of loading rate. The research results provided scientific guidance for promoting the resource utilization of steel slag.
摘要：
Ensuring that land use efficiency and urbanization are in harmony has emerged as a critical concern requiring immediate attention to achieve sustainable urbanization in China. Taking the Chang-Zhu-Tan urban agglomeration (CZTUA) as an example, this study establishes an evaluation index system of land use efficiency and urbanization using multi-source remote sensing data in 2020 and analyzes the coupling coordination degree (CCD) between these factors. Furthermore, the standardization methods and exploratory spatial data analysis method are combined to investigate the spatial correlation of the CCD among land use efficiency and urbanization. The study shows that: (1) In CZTUA, there is a positive correlation between land use efficiency and urbanization and this promotes urbanization. (2) The overall coupling degree in the CZTUA is in the running-in level and most districts are at the elementary or middle rank coordinated levels. (3) The spatial clustering characteristics have the “center-periphery” pattern, with the further away from the core city, the lower the level of coupling coordination becomes. (4) From the perspective of geographical association, the High-High agglomeration, mainly located in Changsha City, showed higher development levels compared to surrounding areas. Development gradually diminished as one moves outward, forming a Low-High agglomeration. Low-Low agglomeration was represented by You, Chaling and Yanling districts. The methodology used in this study is relevant for promoting urbanization and improving land use efficiency in Chinese city clusters.
Ensuring that land use efficiency and urbanization are in harmony has emerged as a critical concern requiring immediate attention to achieve sustainable urbanization in China. Taking the Chang-Zhu-Tan urban agglomeration (CZTUA) as an example, this study establishes an evaluation index system of land use efficiency and urbanization using multi-source remote sensing data in 2020 and analyzes the coupling coordination degree (CCD) between these factors. Furthermore, the standardization methods and exploratory spatial data analysis method are combined to investigate the spatial correlation of the CCD among land use efficiency and urbanization. The study shows that: (1) In CZTUA, there is a positive correlation between land use efficiency and urbanization and this promotes urbanization. (2) The overall coupling degree in the CZTUA is in the running-in level and most districts are at the elementary or middle rank coordinated levels. (3) The spatial clustering characteristics have the “center-periphery” pattern, with the further away from the core city, the lower the level of coupling coordination becomes. (4) From the perspective of geographical association, the High-High agglomeration, mainly located in Changsha City, showed higher development levels compared to surrounding areas. Development gradually diminished as one moves outward, forming a Low-High agglomeration. Low-Low agglomeration was represented by You, Chaling and Yanling districts. The methodology used in this study is relevant for promoting urbanization and improving land use efficiency in Chinese city clusters.
摘要：
SBS-modified asphalt experiences significant deterioration in road performance due to alterations in asphalt composition and oxidative degradation of the SBS modifier during aging. To enhance the performance of aged SBS-modified asphalt, a component optimization system consisting of oleic acid, saturates B, aromatics A, and SBS was developed to explore the mechanisms of regulation. Using molecular dynamics ( MD ) simulations, this study examines the effects of these optimization materials on intermolecular forces, colloidal structure, and mechanical properties of aged SBS-modified asphalt in detail. The findings show that the introduction of optimization materials significantly improves the dispersibility of aged SBS-modified asphalt while suppressing asphaltene aggregation, thereby restoring the colloidal structure. The optimized material system significantly improves the low-temperature rheological properties of asphalt, thereby enhances its cracking resistance under cold conditions. From the perspective of diffusion kinetics, the optimized material composition significantly improves the diffusion rate of each component in the asphalt system. Notably, the optimized oleic acid + SBS exhibits the highest peak diffusion rate, significantly outperforming saturates B + SBS and aromatics A + SBS, demonstrating excellent molecular mobility dynamics.
SBS-modified asphalt experiences significant deterioration in road performance due to alterations in asphalt composition and oxidative degradation of the SBS modifier during aging. To enhance the performance of aged SBS-modified asphalt, a component optimization system consisting of oleic acid, saturates B, aromatics A, and SBS was developed to explore the mechanisms of regulation. Using molecular dynamics ( MD ) simulations, this study examines the effects of these optimization materials on intermolecular forces, colloidal structure, and mechanical properties of aged SBS-modified asphalt in detail. The findings show that the introduction of optimization materials significantly improves the dispersibility of aged SBS-modified asphalt while suppressing asphaltene aggregation, thereby restoring the colloidal structure. The optimized material system significantly improves the low-temperature rheological properties of asphalt, thereby enhances its cracking resistance under cold conditions. From the perspective of diffusion kinetics, the optimized material composition significantly improves the diffusion rate of each component in the asphalt system. Notably, the optimized oleic acid + SBS exhibits the highest peak diffusion rate, significantly outperforming saturates B + SBS and aromatics A + SBS, demonstrating excellent molecular mobility dynamics.
摘要：
Currently, isocyanate modified asphalt (IMA) has gradually attracted attention in the pavement field due to its good mechanical properties and environmental benefits. However, there also exists some challenges, such as high viscosity and poor low-temperature performance, for its further application. In this study, an environmental-friendly potential solving method is proposed by employing waste engine oil (WEO) as a co-modifier with polyaryl polymethylene isocyanate (PAPI). And the effect and modification mechanism of WEO and PAPI on neat asphalt are studied. Specifically, the optimal compositions of PAPI/WEO modified asphalt (PWMA) were firstly determined by learning the effects of the PAPI and WEO amounts on the viscosity, high- and low- temperature performance of neat asphalt. Then, the traditional physical properties, storage stability and aging resistance of PWMA and SBS modified asphalt (SBSMA) were analyzed and compared. Finally, the performance improvement mechanism of PWMA was detected by microscopic analyses. The result shows that adopting WEO as a kind of co-modifier can prepare excellent performance modified asphalt with PAPI. The prepared PWMA qualifies similar viscosity and high- and low- temperature performance to SBSMA, while has the better storage stability and aging resistance. Microscopic test results reveal that in the PWMA, PAPI reacts chemically with the neat asphalt to generate carbamate or urea macromolecular products, while WEO mainly plays the role of adsorbent and filler. These findings are significant for guiding the performance regulation of IMA by the environmental-friendly method.
Currently, isocyanate modified asphalt (IMA) has gradually attracted attention in the pavement field due to its good mechanical properties and environmental benefits. However, there also exists some challenges, such as high viscosity and poor low-temperature performance, for its further application. In this study, an environmental-friendly potential solving method is proposed by employing waste engine oil (WEO) as a co-modifier with polyaryl polymethylene isocyanate (PAPI). And the effect and modification mechanism of WEO and PAPI on neat asphalt are studied. Specifically, the optimal compositions of PAPI/WEO modified asphalt (PWMA) were firstly determined by learning the effects of the PAPI and WEO amounts on the viscosity, high- and low- temperature performance of neat asphalt. Then, the traditional physical properties, storage stability and aging resistance of PWMA and SBS modified asphalt (SBSMA) were analyzed and compared. Finally, the performance improvement mechanism of PWMA was detected by microscopic analyses. The result shows that adopting WEO as a kind of co-modifier can prepare excellent performance modified asphalt with PAPI. The prepared PWMA qualifies similar viscosity and high- and low- temperature performance to SBSMA, while has the better storage stability and aging resistance. Microscopic test results reveal that in the PWMA, PAPI reacts chemically with the neat asphalt to generate carbamate or urea macromolecular products, while WEO mainly plays the role of adsorbent and filler. These findings are significant for guiding the performance regulation of IMA by the environmental-friendly method.
摘要：
This research analyzed the characteristics of aggregate contact chain networks based on complex network theory. The contact chain network was extracted using Digital Image Processing (DIP) technology and Three-Dimensional (3D) reconstruction technology. The change rule of the contact chain network of asphalt mixture was analyzed using the complex network theory. From the results of the analysis, the filling particles existed during the compaction. The 4.75–9.5 mm and 9.5–13.2 mm aggregates may rotate to increase the stability of the skeleton structure. The clustering coefficient of the aggregate increased as the asphalt mixture was compacted, and the aggregate with a small size had a larger clustering coefficient. The distribution of shortest path length in each compaction stage obeyed the Gaussian distribution. The average shortest path length decreased with the increase of the compactness of the specimen, indicating that there was a good correlation between shortest path length and compactness.
This research analyzed the characteristics of aggregate contact chain networks based on complex network theory. The contact chain network was extracted using Digital Image Processing (DIP) technology and Three-Dimensional (3D) reconstruction technology. The change rule of the contact chain network of asphalt mixture was analyzed using the complex network theory. From the results of the analysis, the filling particles existed during the compaction. The 4.75–9.5 mm and 9.5–13.2 mm aggregates may rotate to increase the stability of the skeleton structure. The clustering coefficient of the aggregate increased as the asphalt mixture was compacted, and the aggregate with a small size had a larger clustering coefficient. The distribution of shortest path length in each compaction stage obeyed the Gaussian distribution. The average shortest path length decreased with the increase of the compactness of the specimen, indicating that there was a good correlation between shortest path length and compactness.
关键词：
transient infiltration;unsaturated soil;Rankine earth pressure;shear strength envelope shell;infiltration transitoire;sol non saturé;pression de terre selon Rankine;coque enveloppante de la résistance au cisaillement
摘要：
To investigate the spatiotemporal effect of transient rainfall infiltration on the earth pressures, a novel solution scheme is proposed by integrating transient seepage and the envelope shell model of unsaturated shear strength. The acquisition method of equivalent parameters (i.e., cohesion and friction angle) is put forward, presenting the nonlinearity of shear strength in both two dimensions: net normal stress and matric suction. Moreover, Iverson model is modified to depict the general initial distribution of pressure head and the post-rainfall dissipation by introducing the Gaussian function and the recession coefficient. Finally, the nonlinear Rankine earth pressure characteristics are captured by linking the matric suction, mass density, and the shear strength parameters in a self-consistent fashion. Case validation and parametric analysis show good adaptability of the proposed model in calculating the unsaturated earth pressure with depicting the subtle and overlooked effect of soil unit weight during water infiltration. Thus, it contributes to evaluating the influence of transient infiltration on the performance of retaining structures under rainfall conditions.
摘要：
为研究生物酶土壤固化剂与水泥复合固化红砂岩土的性能，探究复合固化红砂岩土用于高速公路底基层的可行性，以及研究生物酶土壤固化剂掺量对固化土力学性能与耐久性能的影响，并结合扫描电子显微镜微观试验分析稳定机理。结果表明：生物酶土壤固化剂的掺入可提高固化土的无侧限抗压强度、劈裂强度、抵抗贯入强度和弹性模量，最佳掺量为2；相同应力比下，复合固化土的疲劳寿命相比水泥单一固化土增长不明显，相同应力下，复合固化土的疲劳寿命相比水泥单一固化土显著增加。本研究为复合固化红砂岩土用于高速公路底基层提供参考。 您的浏览器不支持 audio 元素。 AI语音播报 In order to study the performance of red sandstone soil solidified by biological enzyme soil curing agent and cement, and to explore the feasibility of composite solidified red sandstone soil used in expressway subbase, the effects of biological enzyme soil curing agent dosages on mechanical properties and durability of solidified soil were carried out, and microscopic tests were carried out in combination with scanning electron microscopy to analyze the stability mechanism. The results show that the addition of biological enzyme soil curing agent improves the unconfined compressive strength, splitting tensile strength, penetration resistance strength and elastic modulus of solidified soil, and the optimal dosage is 2. Under the same stress ratio, the fatigue life of composite solidified soil has no obvious advantage compared with that of single solidified soil by cement, but under the same stress, the fatigue life of composite solidified soil increases significantly compared with that of single solidified soil by cement. This study provides a reference for the practical engineering application of composite solidified red sandstone soil in expressway subbase.
