In modern transportation,pavement is one of the most important civil infrastructures for the movement of vehicles and pedestrians.Pavement service quality and service life are of great importance for civil engineers a...In modern transportation,pavement is one of the most important civil infrastructures for the movement of vehicles and pedestrians.Pavement service quality and service life are of great importance for civil engineers as they directly affect the regular service for the users.Therefore,monitoring the health status of pavement before irreversible damage occurs is essential for timely maintenance,which in turn ensures public transportation safety.Many pavement damages can be detected and analyzed by monitoring the structure dynamic responses and evaluating road surface conditions.Advanced technologies can be employed for the collection and analysis of such data,including various intrusive sensing techniques,image processing techniques,and machine learning methods.This review summarizes the state-ofthe-art of these three technologies in pavement engineering in recent years and suggests possible developments for future pavement monitoring and analysis based on these approaches.展开更多
Contemporary demands necessitate the swift and accurate detection of cracks in critical infrastructures,including tunnels and pavements.This study proposed a transfer learning-based encoder-decoder method with visual ...Contemporary demands necessitate the swift and accurate detection of cracks in critical infrastructures,including tunnels and pavements.This study proposed a transfer learning-based encoder-decoder method with visual explanations for infrastructure crack segmentation.Firstly,a vast dataset containing 7089 images was developed,comprising diverse conditions—simple and complex crack patterns as well as clean and rough backgrounds.Secondly,leveraging transfer learning,an encoder-decoder model with visual explanations was formulated,utilizing varied pre-trained convolutional neural network(CNN)as the encoder.Visual explanations were achieved through gradient-weighted class activation mapping(Grad-CAM)to interpret the CNN segmentation model.Thirdly,accuracy,complexity(computation and model),and memory usage assessed CNN feasibility in practical engineering.Model performance was gauged via prediction and visual explanation.The investigation encompassed hyperparameters,data augmentation,deep learning from scratch vs.transfer learning,segmentation model architectures,segmentation model encoders,and encoder pre-training strategies.Results underscored transfer learning’s potency in enhancing CNN accuracy for crack segmentation,surpassing deep learning from scratch.Notably,encoder classification accuracy bore no significant correlation with CNN segmentation accuracy.Among all tested models,UNet-EfficientNet_B7 excelled in crack segmentation,harmonizing accuracy,complexity,memory usage,prediction,and visual explanation.展开更多
The increasing impact of the greenhouse effect on ecosystems is prompting transportation agencies to seek methods for reducing CO_(2)emissions during pavement construction and maintenance.Additionally,the laboratory m...The increasing impact of the greenhouse effect on ecosystems is prompting transportation agencies to seek methods for reducing CO_(2)emissions during pavement construction and maintenance.Additionally,the laboratory mix design process,which involves selecting aggregate gradation and binder content,is time-consuming and labor-intensive.To accelerate the traditional mix design procedure,this study presented a mix design procedure that can automatically determine gradation and binder content based on machine learning(ML)and a meta-heuristic algorithm.Specifically,ML approaches were employed to model the relationship between volumetric properties(mixture bulk specific gravity(Gmb)and air void(VV))and both mixture component properties and mixture proportion,based on a dataset collected from literature with 660 mixture designs.Integrated with the prediction of ML models and the modified multi-objective grey wolf optimization(MOGWO)algorithm,an automatic asphalt mix design was proposed to pursue three goals,including VV,cost,and CO_(2)emission.The results indicated that least squares support vector regression(LSSVR)and e Xtreme gradient boosting(XGBoost)achieved the highest prediction accuracies(correlation coefficient:0.92 for VV and 0.96 for Gmb).The MOGWO algorithm successfully found the 26 optimal mix designs for the case of VV vs.cost vs.CO_(2)emission.Compared to the traditional laboratory design,the optimal mixture with VV of4%achieves a cost saving of 2.46%and a reduction of 4.03%in carbon emission.The volumetric properties of the mixtures output by the approach also align closely with values measured in a laboratory.展开更多
Microwave heating,which is used for pre-treatment of concrete before it is comminuted,stands as a strong candidate for selective liberation of multiphase materials like concrete.This paper is concerned with the select...Microwave heating,which is used for pre-treatment of concrete before it is comminuted,stands as a strong candidate for selective liberation of multiphase materials like concrete.This paper is concerned with the selective liberation of concrete's raw constituents(particularly aggregate)for recycling by considering the water content of concrete as a parameter of microwave heating for the first time.The deterioration law of the concrete's performance was characterized by the variation in the splitting tensile strength and relative dynamic modulus after heating by microwave at different water contents.Besides,tests were conducted to evaluate the performance of the interface transition zone(ITZ)between aggregate and mortar as well as to investigate the reasons for the stripping behavior of aggregate-mortar,which included the interface tensile strength test,temperature measurement,and porosity test.The deterioration law of splitting tensile strength and relative dynamic modulus revealed that the performance of concrete was subject to different degrees of damage depending on the water content.Furthermore,experimental results showed that interface bonding strength between aggregate and mortar was dramatically impaired,and a large temperature difference was generated between the aggregate and mortar during microwave heating.Meanwhile,the permeable pores increased considerably even when the specimens were dried.In the presence of water,the intactness of ITZ between aggregate and mortar was destroyed by microwave heating,and its performance was significantly lowered,which led to the occurrence of stripping behavior between aggregate and mortar.This was reaffirmed by the microstructure presented by scanning electron microscopy.Thus,the newly developed microwave pretreatment improved by providing appropriate water contents for concrete corresponding to different strength grades is a promising method for recycling aggregate from waste concrete.展开更多
Damage to semi-rigid base asphalt pavement is related to improper matching of the pavement structure moduli.This study mainly focused on the modulus matching of structural layers and the development of a pavement stru...Damage to semi-rigid base asphalt pavement is related to improper matching of the pavement structure moduli.This study mainly focused on the modulus matching of structural layers and the development of a pavement structure optimization method.First,the modulus loss of existing pavement structures was analysed,and a three-dimensional finite element model was established based on the existing pavement.Second,the influence of the modulus of each structural layer on the mechanical response indicators and fatigue life was analysed.Based on the results,a pavement structure design method using the smoothness of the stress-strain curve as the modulus matching criterion of the structural layers was proposed.And it was found that a strain convex point was present and that the stress mutation between the structural layers was significant when the modulus matching of the pavement structure was reasonable.Further,the evaluation indicators were divided into two groups,namely,mechanical indicators and fatigue life indicators.And it was proposed an optimized pavement structure design method based on modulus matching and multi-indicator range analysis.Finally,the optimal modulus combination of pavement structure was determined by this method.The research systematically studied the influence of the modulus of each structural layer on the mechanical response and fatigue life of the pavement,and proposed the concept and specific executive criteria of modulus matching for the first time.Meanwhile,it also provided an effective optimization method for pavement structure design.展开更多
Mechanical properties of rock materials are related to textural characteristics. The relationships between mechanical properties and textural characteristics have been extensively investigated for differently types of...Mechanical properties of rock materials are related to textural characteristics. The relationships between mechanical properties and textural characteristics have been extensively investigated for differently types of rocks through experimental tests. Based on the experimental test data, single- and multiple- variant regression analyses are conducted among mechanical properties and textural characteristics. Textural characteristics of rock materials are influenced by the following factors： mineral composition, size, shape, and spatial distribution of mineral grains, porosity, and inherent microcracks. This study focuses on the first two： mineral composition and grain size. This study comprehensively summarizes the regression equations between mechanical properties and mineral content and the regression equations between mechanical properties and grain size. Further research directions are suggested at the end of this study.展开更多
The interface between asphalt binder and mineral aggregate directly affects the service life of pavement because the defects and stress concentration occur more easily there. The interaction between asphalt binder and...The interface between asphalt binder and mineral aggregate directly affects the service life of pavement because the defects and stress concentration occur more easily there. The interaction between asphalt binder and mineral aggregate is the main cause of forming the interface. This paper presents an extensive review on the test technologies and analysis methods of interfacial interaction, including molecular dynamics simulation, phase field approach, absorption tests, rheological methods and macro mechanical tests. All of the studies conducted on this topic clearly indicated that the interfacial interaction between asphalt binder and mineral aggregate is a physical-chemical process, and can be qualitatively characterized by microscopical technique （such as SEM and AFM）, and also can be quantitatively evaluated by rheological methods and interfacial mechanical tests. Molecular dynamics simulation and phase field approach were also demonstrated to be effective methods to study the interfacial behavior and its mechanism.展开更多
The road is one of the most important civil infrastructures for serving society,where its service quality and life have direct impacts on the safety and comfort of users.Therefore,road construction,condition detection...The road is one of the most important civil infrastructures for serving society,where its service quality and life have direct impacts on the safety and comfort of users.Therefore,road construction,condition detection and monitoring,and timely maintenance are particularly important for engineers.Many engineering applications of industrial informatics approaches,like image processing technology,widely used computer-based algorithms,and advanced sensors,have been initially and gradually applied to roads.This state-of-the-art review first summarized the research on industrial applications of advanced information technologies in recent years,while analyzing and comparing the advantages and disadvantages of each technology.Especially,five topics were focused on road construction,road maintenance with decision strategy,road structure evaluation,smart sensing in the road,and cooperative vehicle infrastructure system.It is expected that advanced industrial informatics can help engineers promote the development of smart,safe,and sustainable roads.展开更多
The waste clay bricks from debris of buildings were evaluated through lab tests as environ- mental friendly materials for pavement sub-base in the research. Five sets of coarse aggregates which contained 0, 25%, 50%, ...The waste clay bricks from debris of buildings were evaluated through lab tests as environ- mental friendly materials for pavement sub-base in the research. Five sets of coarse aggregates which contained 0, 25%, 50%, 75% and 100% crushed bricks, respectively, were blended with sand and treated by 5 % cement. The test results indicated that cement treated aggregate which contains crushed clay brick aggregate had a lower maximum dry density （MDD） and a higher optimum moisture content （OMC）. Moreover, the unconfined compressive strength （UCS）, resilience modulus, splitting strength, and frost resistance performance of the specimens decreased with increase of the amount of crushed clay brick aggregate. On the other hand, it can be observed that the use of crushed clay brick in the mixture decreased the dry shrinkage strain of the specimens. Compared with the asphalt pave- ment design specifications of China, the results imply that the substitution rate of natural aggregate with crushed clay brick aggregate in the cement treated aggregate sub-base material should be less than 50% （5 % cement content in the mixture）. Furthermore, it needs to be noted that the cement treated aggre- gate which contains crushed clay bricks should be cautiously used in the cold region due to its insuffi- cient frost resistance performance.展开更多
Pavement distress detection(PDD)plays a vital role in planning timely pavement maintenance that improves pavement service life.In order to promote the development of PDD technologies and find out the insufficiencies i...Pavement distress detection(PDD)plays a vital role in planning timely pavement maintenance that improves pavement service life.In order to promote the development of PDD technologies and find out the insufficiencies in PDD field,this paper reviews the technical development history and characteristics of various PDD technologies,which contributes to the current state of research on PDD.First,processes of PDD are briefly introduced.The PDD technologies based on radar ranging,2D image,laser ranging and 3 D structured light are illustrated.The newest 3D PDD technology based on interference fringe,which has better accuracy,is in progress.The principles and implementation processes of these methods are discussed.Finally,the shortcomings of these technologies in the field of PDD are concluded.Recommendations for future development are provided.The research results show that various PDD technologies have been continuously improved,developed,over the past decade,and have achieved a series of results.However,the measurements from existing PDD technologies can not be metrological traced to acquire the true dimensions of pavement distresses.The lack of metrological traceability technology in the PDD field needs to be further solved.In order to achieve more accurate and efficient PDD,the metrological traceability technology of PDD systems has become the future development direction in this field.展开更多
Pavement is an important part of transportation infrastructure.In order to maintain pavement before the damage and improve the service quality,it is necessary to develop an intelligent and durable pavement information...Pavement is an important part of transportation infrastructure.In order to maintain pavement before the damage and improve the service quality,it is necessary to develop an intelligent and durable pavement information monitoring system.However,the pavement dynamic response monitoring is highly costly,easily obsolete and statistically redundant.The emergence of the Internet of Things(IoT)technology promises to change that.In this paper,an architecture of a distributed road IoT monitoring system is proposed,which has an acquisition layer,a preprocessing layer,a processing layer,an interaction layer,an energy layer and a network layer.Then,a prototype wireless pavement vibration monitoring system based on the IoT is developed,which consists of a number of wireless sensing nodes,a gateway,a remote server and a browser.Finally,data preprocessing,wireless communication,time synchronization,data processing and visualization,which represent the key to an effective system,are tested and discussed.The prototype wireless pavement vibration monitoring system provides a viable scheme for upgrading the IoT system and its application in the road infrastructures.In the future,any smart road will have an IoT wireless monitoring system to monitor the traffic,environment,and pavement information,which help enable traffic guidance,signal control,danger warning,scientific maintenance decision-making.展开更多
According to specific bridge environment, optimal design piezoelectric cantilever beam structure by using results of theoretical calculations and simulation, verify natural frequencies of piezoelectric cantilever beam...According to specific bridge environment, optimal design piezoelectric cantilever beam structure by using results of theoretical calculations and simulation, verify natural frequencies of piezoelectric cantilever beam and production ability of data by experiment, thus formed a complete set of design method of piezoelectric cantilever beam. Considering natural frequency of vibration and intensity of the beam body, design a new type of piezoelectric cantilever beam structure. Paper analyzes the principle of sensor data acquisition and transmission, design a hardware integration system include signal conversion module, microcontroller module and wireless transmission module, test local read and wireless transmission for the combination structure of cantilever beam and data collection card, experimental verification of the radio piezoelectric vibrating cantilever vibration response is intact, the beam produced signal by vibration, acquisition card converts and wireless transmit data, this proved a good and intuitive linear response in simulation of bridge vibration test. Finally, the paper designed a kind of new wireless sensor of vibration cantilever beam, suitable for small bridge health monitoring based on Internet of things.展开更多
The fatigue damage is one of the most common distresses observed on the asphalt concrete pavement.To thoroughly understand the fatigue of asphalt concrete,the behaviors of the major components of asphalt concrete unde...The fatigue damage is one of the most common distresses observed on the asphalt concrete pavement.To thoroughly understand the fatigue of asphalt concrete,the behaviors of the major components of asphalt concrete under cyclic loading are investigated respectively in this study.A new experiment method is developed to evaluate the performances of asphalt binder,mastic and fine aggregates mixture under cyclic tensile loading.The fatigue test results of asphalt binder show that the fatigue performance of asphalt binder is closely related with loading magnitude,temperature and loading rate.Mastic specimens with different filler content are tested and the results indicate that mastic specimens with 30%filler content show better fatigue resistance and higher permanent strain.The micro-structure analysis of mastic and mixture indicates that the fatigue resistance is closely related with the air void content of specimen.3D digital specimens are developed to model the fatigue of the asphalt binder,mastic and mixture specimens based on the finite element method(FEM).Fatigue damage of asphalt concrete is simplified by a damage model.With proper selection of damage parameters,the simulation results agree well with laboratory test results and can be used as a basis for future fatigue research.展开更多
The tensile behavior of hybrid fiber reinforced concrete(HFRC)is important to the design of HFRC and HFRC structure.This study used an artificial neural network(ANN)model to describe the tensile behavior of HFRC.This ...The tensile behavior of hybrid fiber reinforced concrete(HFRC)is important to the design of HFRC and HFRC structure.This study used an artificial neural network(ANN)model to describe the tensile behavior of HFRC.This ANN model can describe well the tensile stress-strain curve of HFRC with the consideration of 23 features of HFRC.In the model,three methods to process output features(no-processed,mid-processed,and processed)are discussed and the mid-processed method is recommended to achieve a better reproduction of the experimental data.This means the strain should be normalized while the stress doesn’t need normalization.To prepare the database of the model,both many direct tensile test results and the relevant literature data are collected.Moreover,a traditional equation-based model is also established and compared with the ANN model.The results show that the ANN model has a better prediction than the equation-based model in terms of the tensile stress-strain curve,tensile strength,and strain corresponding to tensile strength of HFRC.Finally,the sensitivity analysis of the ANN model is also performed to analyze the contribution of each input feature to the tensile strength and strain corresponding to tensile strength.The mechanical properties of plain concrete make the main contribution to the tensile strength and strain corresponding to tensile strength,while steel fibers tend to make more contributions to these two items than PVA fibers.展开更多
In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste （HCP） under a tensile force. A three-dimensional （3D） multiscale mechanical model is established u...In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste （HCP） under a tensile force. A three-dimensional （3D） multiscale mechanical model is established using the combined Discrete Element Method （DEM）-Molecular Dynamics （MD） method in LAMMPS （Large-scale Atomic/ Molecular Massively Parallel Simulator）. In the 3D model, HCP consists of discrete particles and atoms. Simulation results show that the combined DEM-MD model is computationally efficient with good accuracy in predicting tensile failures of HCP.展开更多
The thermal expansion mismatch between cement mortar and aggregate at high temperature is one of the main reasons causing the deterioration of concrete at high temperature.In this study,the thermal damage of concrete ...The thermal expansion mismatch between cement mortar and aggregate at high temperature is one of the main reasons causing the deterioration of concrete at high temperature.In this study,the thermal damage of concrete caused by the thermal expansion mismatch between aggregate and cement mortar was investigated using a meso-scale concrete model.The meso-scale concrete model is composed of mortar,aggregate and the interfacial transition zone(ITZ).Laboratory tests on the mechanical properties of cement mortar at high temperature were conducted to provide the necessary mechanical parameter for the meso-scale concrete model.The simulation results show that the particle size,content,distribution and mechanical properties of the aggregate have an effect on the thermal damage of concrete at high temperature.The smaller the particle size of concrete aggregate and the higher the elastic modulus of aggregate,the greater the damage of concrete under high temperature.Due to the increasing thermal expansion difference between aggregate and cement mortar,and the deterioration of the cement mortar with the increasing temperature,the damage of concrete increased sharply after 500℃.展开更多
基金supported by the National Key R&D Program of China(2017YFF0205600)the International Research Cooperation Seed Fund of Beijing University of Technology(2018A08)+1 种基金Science and Technology Project of Beijing Municipal Commission of Transport(2018-kjc-01-213)the Construction of Service Capability of Scientific and Technological Innovation-Municipal Level of Fundamental Research Funds(Scientific Research Categories)of Beijing City(PXM2019_014204_500032).
文摘In modern transportation,pavement is one of the most important civil infrastructures for the movement of vehicles and pedestrians.Pavement service quality and service life are of great importance for civil engineers as they directly affect the regular service for the users.Therefore,monitoring the health status of pavement before irreversible damage occurs is essential for timely maintenance,which in turn ensures public transportation safety.Many pavement damages can be detected and analyzed by monitoring the structure dynamic responses and evaluating road surface conditions.Advanced technologies can be employed for the collection and analysis of such data,including various intrusive sensing techniques,image processing techniques,and machine learning methods.This review summarizes the state-ofthe-art of these three technologies in pavement engineering in recent years and suggests possible developments for future pavement monitoring and analysis based on these approaches.
基金the National Natural Science Foundation of China(Grant Nos.52090083 and 52378405)Key Technology R&D Plan of Yunnan Provincial Department of Science and Technology(Grant No.202303AA080003)for their financial support.
文摘Contemporary demands necessitate the swift and accurate detection of cracks in critical infrastructures,including tunnels and pavements.This study proposed a transfer learning-based encoder-decoder method with visual explanations for infrastructure crack segmentation.Firstly,a vast dataset containing 7089 images was developed,comprising diverse conditions—simple and complex crack patterns as well as clean and rough backgrounds.Secondly,leveraging transfer learning,an encoder-decoder model with visual explanations was formulated,utilizing varied pre-trained convolutional neural network(CNN)as the encoder.Visual explanations were achieved through gradient-weighted class activation mapping(Grad-CAM)to interpret the CNN segmentation model.Thirdly,accuracy,complexity(computation and model),and memory usage assessed CNN feasibility in practical engineering.Model performance was gauged via prediction and visual explanation.The investigation encompassed hyperparameters,data augmentation,deep learning from scratch vs.transfer learning,segmentation model architectures,segmentation model encoders,and encoder pre-training strategies.Results underscored transfer learning’s potency in enhancing CNN accuracy for crack segmentation,surpassing deep learning from scratch.Notably,encoder classification accuracy bore no significant correlation with CNN segmentation accuracy.Among all tested models,UNet-EfficientNet_B7 excelled in crack segmentation,harmonizing accuracy,complexity,memory usage,prediction,and visual explanation.
基金sponsored by a grant from the Center for Integrated Asset Management for Multimodal Transportation Infrastructure Systems(CIAMTIS),a US Department of Transportation,University Transportation Center,United States,under federal grant number 69A3551847103。
文摘The increasing impact of the greenhouse effect on ecosystems is prompting transportation agencies to seek methods for reducing CO_(2)emissions during pavement construction and maintenance.Additionally,the laboratory mix design process,which involves selecting aggregate gradation and binder content,is time-consuming and labor-intensive.To accelerate the traditional mix design procedure,this study presented a mix design procedure that can automatically determine gradation and binder content based on machine learning(ML)and a meta-heuristic algorithm.Specifically,ML approaches were employed to model the relationship between volumetric properties(mixture bulk specific gravity(Gmb)and air void(VV))and both mixture component properties and mixture proportion,based on a dataset collected from literature with 660 mixture designs.Integrated with the prediction of ML models and the modified multi-objective grey wolf optimization(MOGWO)algorithm,an automatic asphalt mix design was proposed to pursue three goals,including VV,cost,and CO_(2)emission.The results indicated that least squares support vector regression(LSSVR)and e Xtreme gradient boosting(XGBoost)achieved the highest prediction accuracies(correlation coefficient:0.92 for VV and 0.96 for Gmb).The MOGWO algorithm successfully found the 26 optimal mix designs for the case of VV vs.cost vs.CO_(2)emission.Compared to the traditional laboratory design,the optimal mixture with VV of4%achieves a cost saving of 2.46%and a reduction of 4.03%in carbon emission.The volumetric properties of the mixtures output by the approach also align closely with values measured in a laboratory.
基金the financial support from the open project funds for National Major Science and Technology Infrastructure of Materials Service Safety Assessment Facilities,China(MSAF-2020-106)the National Natural Science Foundation of China(No.51808051)。
文摘Microwave heating,which is used for pre-treatment of concrete before it is comminuted,stands as a strong candidate for selective liberation of multiphase materials like concrete.This paper is concerned with the selective liberation of concrete's raw constituents(particularly aggregate)for recycling by considering the water content of concrete as a parameter of microwave heating for the first time.The deterioration law of the concrete's performance was characterized by the variation in the splitting tensile strength and relative dynamic modulus after heating by microwave at different water contents.Besides,tests were conducted to evaluate the performance of the interface transition zone(ITZ)between aggregate and mortar as well as to investigate the reasons for the stripping behavior of aggregate-mortar,which included the interface tensile strength test,temperature measurement,and porosity test.The deterioration law of splitting tensile strength and relative dynamic modulus revealed that the performance of concrete was subject to different degrees of damage depending on the water content.Furthermore,experimental results showed that interface bonding strength between aggregate and mortar was dramatically impaired,and a large temperature difference was generated between the aggregate and mortar during microwave heating.Meanwhile,the permeable pores increased considerably even when the specimens were dried.In the presence of water,the intactness of ITZ between aggregate and mortar was destroyed by microwave heating,and its performance was significantly lowered,which led to the occurrence of stripping behavior between aggregate and mortar.This was reaffirmed by the microstructure presented by scanning electron microscopy.Thus,the newly developed microwave pretreatment improved by providing appropriate water contents for concrete corresponding to different strength grades is a promising method for recycling aggregate from waste concrete.
基金supported by grant from the National Key R&D Program of China(2019YFE0117600).
文摘Damage to semi-rigid base asphalt pavement is related to improper matching of the pavement structure moduli.This study mainly focused on the modulus matching of structural layers and the development of a pavement structure optimization method.First,the modulus loss of existing pavement structures was analysed,and a three-dimensional finite element model was established based on the existing pavement.Second,the influence of the modulus of each structural layer on the mechanical response indicators and fatigue life was analysed.Based on the results,a pavement structure design method using the smoothness of the stress-strain curve as the modulus matching criterion of the structural layers was proposed.And it was found that a strain convex point was present and that the stress mutation between the structural layers was significant when the modulus matching of the pavement structure was reasonable.Further,the evaluation indicators were divided into two groups,namely,mechanical indicators and fatigue life indicators.And it was proposed an optimized pavement structure design method based on modulus matching and multi-indicator range analysis.Finally,the optimal modulus combination of pavement structure was determined by this method.The research systematically studied the influence of the modulus of each structural layer on the mechanical response and fatigue life of the pavement,and proposed the concept and specific executive criteria of modulus matching for the first time.Meanwhile,it also provided an effective optimization method for pavement structure design.
文摘Mechanical properties of rock materials are related to textural characteristics. The relationships between mechanical properties and textural characteristics have been extensively investigated for differently types of rocks through experimental tests. Based on the experimental test data, single- and multiple- variant regression analyses are conducted among mechanical properties and textural characteristics. Textural characteristics of rock materials are influenced by the following factors： mineral composition, size, shape, and spatial distribution of mineral grains, porosity, and inherent microcracks. This study focuses on the first two： mineral composition and grain size. This study comprehensively summarizes the regression equations between mechanical properties and mineral content and the regression equations between mechanical properties and grain size. Further research directions are suggested at the end of this study.
文摘The interface between asphalt binder and mineral aggregate directly affects the service life of pavement because the defects and stress concentration occur more easily there. The interaction between asphalt binder and mineral aggregate is the main cause of forming the interface. This paper presents an extensive review on the test technologies and analysis methods of interfacial interaction, including molecular dynamics simulation, phase field approach, absorption tests, rheological methods and macro mechanical tests. All of the studies conducted on this topic clearly indicated that the interfacial interaction between asphalt binder and mineral aggregate is a physical-chemical process, and can be qualitatively characterized by microscopical technique （such as SEM and AFM）, and also can be quantitatively evaluated by rheological methods and interfacial mechanical tests. Molecular dynamics simulation and phase field approach were also demonstrated to be effective methods to study the interfacial behavior and its mechanism.
基金the Hunan Department of Transportation(No.202152)in ChinaNatural Science Foundation of Heilongjiang Province of China(JJ2020ZD0015)+1 种基金the Opening Project Fund of Materials Service Safety Assessment Facilities(MSAF-2021-005,MSAF-2021-109)German Research Foundation(DFG)under Grant No.SFB/TRR 339(453596084)。
文摘The road is one of the most important civil infrastructures for serving society,where its service quality and life have direct impacts on the safety and comfort of users.Therefore,road construction,condition detection and monitoring,and timely maintenance are particularly important for engineers.Many engineering applications of industrial informatics approaches,like image processing technology,widely used computer-based algorithms,and advanced sensors,have been initially and gradually applied to roads.This state-of-the-art review first summarized the research on industrial applications of advanced information technologies in recent years,while analyzing and comparing the advantages and disadvantages of each technology.Especially,five topics were focused on road construction,road maintenance with decision strategy,road structure evaluation,smart sensing in the road,and cooperative vehicle infrastructure system.It is expected that advanced industrial informatics can help engineers promote the development of smart,safe,and sustainable roads.
基金supports from the program for New Century Excellent Talents in University,Ministry of Education of China (No.NCET -08-0748 )the Special Fund for Scientific Research of Central Colleges , Chang'an University ( No. CHD2011TD014 )Traffic Science and Technology Talents Training Plan , Ministry of Transport of China ( No . 2012-16 )
文摘The waste clay bricks from debris of buildings were evaluated through lab tests as environ- mental friendly materials for pavement sub-base in the research. Five sets of coarse aggregates which contained 0, 25%, 50%, 75% and 100% crushed bricks, respectively, were blended with sand and treated by 5 % cement. The test results indicated that cement treated aggregate which contains crushed clay brick aggregate had a lower maximum dry density （MDD） and a higher optimum moisture content （OMC）. Moreover, the unconfined compressive strength （UCS）, resilience modulus, splitting strength, and frost resistance performance of the specimens decreased with increase of the amount of crushed clay brick aggregate. On the other hand, it can be observed that the use of crushed clay brick in the mixture decreased the dry shrinkage strain of the specimens. Compared with the asphalt pave- ment design specifications of China, the results imply that the substitution rate of natural aggregate with crushed clay brick aggregate in the cement treated aggregate sub-base material should be less than 50% （5 % cement content in the mixture）. Furthermore, it needs to be noted that the cement treated aggre- gate which contains crushed clay bricks should be cautiously used in the cold region due to its insuffi- cient frost resistance performance.
基金supported by National Key Research and Development Program of China(Grant No.2017YFF0205600)。
文摘Pavement distress detection(PDD)plays a vital role in planning timely pavement maintenance that improves pavement service life.In order to promote the development of PDD technologies and find out the insufficiencies in PDD field,this paper reviews the technical development history and characteristics of various PDD technologies,which contributes to the current state of research on PDD.First,processes of PDD are briefly introduced.The PDD technologies based on radar ranging,2D image,laser ranging and 3 D structured light are illustrated.The newest 3D PDD technology based on interference fringe,which has better accuracy,is in progress.The principles and implementation processes of these methods are discussed.Finally,the shortcomings of these technologies in the field of PDD are concluded.Recommendations for future development are provided.The research results show that various PDD technologies have been continuously improved,developed,over the past decade,and have achieved a series of results.However,the measurements from existing PDD technologies can not be metrological traced to acquire the true dimensions of pavement distresses.The lack of metrological traceability technology in the PDD field needs to be further solved.In order to achieve more accurate and efficient PDD,the metrological traceability technology of PDD systems has become the future development direction in this field.
基金funded by Beijing Major Science and Technology Projects(grant number Z191100008019002)Fundamental Research Funds for the Central University(FRFTP-19-050A1,FRF-BD-19-001A,FRF-MP-19-014)Technology Innovation and Demonstration Project(2021)of the Department of Transport of Yunnan Province。
文摘Pavement is an important part of transportation infrastructure.In order to maintain pavement before the damage and improve the service quality,it is necessary to develop an intelligent and durable pavement information monitoring system.However,the pavement dynamic response monitoring is highly costly,easily obsolete and statistically redundant.The emergence of the Internet of Things(IoT)technology promises to change that.In this paper,an architecture of a distributed road IoT monitoring system is proposed,which has an acquisition layer,a preprocessing layer,a processing layer,an interaction layer,an energy layer and a network layer.Then,a prototype wireless pavement vibration monitoring system based on the IoT is developed,which consists of a number of wireless sensing nodes,a gateway,a remote server and a browser.Finally,data preprocessing,wireless communication,time synchronization,data processing and visualization,which represent the key to an effective system,are tested and discussed.The prototype wireless pavement vibration monitoring system provides a viable scheme for upgrading the IoT system and its application in the road infrastructures.In the future,any smart road will have an IoT wireless monitoring system to monitor the traffic,environment,and pavement information,which help enable traffic guidance,signal control,danger warning,scientific maintenance decision-making.
文摘According to specific bridge environment, optimal design piezoelectric cantilever beam structure by using results of theoretical calculations and simulation, verify natural frequencies of piezoelectric cantilever beam and production ability of data by experiment, thus formed a complete set of design method of piezoelectric cantilever beam. Considering natural frequency of vibration and intensity of the beam body, design a new type of piezoelectric cantilever beam structure. Paper analyzes the principle of sensor data acquisition and transmission, design a hardware integration system include signal conversion module, microcontroller module and wireless transmission module, test local read and wireless transmission for the combination structure of cantilever beam and data collection card, experimental verification of the radio piezoelectric vibrating cantilever vibration response is intact, the beam produced signal by vibration, acquisition card converts and wireless transmit data, this proved a good and intuitive linear response in simulation of bridge vibration test. Finally, the paper designed a kind of new wireless sensor of vibration cantilever beam, suitable for small bridge health monitoring based on Internet of things.
基金This paper was financially supported by Guangxi Governor Grant under approval number of 2010-169the National Natural Science Foundation of China under Grant number of 41162011+2 种基金Guangxi Grand Natural Science Foundation under contract number of 2011GXNSFD018001Guangxi Grand Natural Science Foundation under the number of 2012GXNSFCB053005the grant of the Guangxi Key Laboratory of Spatial Information and Geomatics under contract number,GuiKeNeng110-31-08-01.
文摘The fatigue damage is one of the most common distresses observed on the asphalt concrete pavement.To thoroughly understand the fatigue of asphalt concrete,the behaviors of the major components of asphalt concrete under cyclic loading are investigated respectively in this study.A new experiment method is developed to evaluate the performances of asphalt binder,mastic and fine aggregates mixture under cyclic tensile loading.The fatigue test results of asphalt binder show that the fatigue performance of asphalt binder is closely related with loading magnitude,temperature and loading rate.Mastic specimens with different filler content are tested and the results indicate that mastic specimens with 30%filler content show better fatigue resistance and higher permanent strain.The micro-structure analysis of mastic and mixture indicates that the fatigue resistance is closely related with the air void content of specimen.3D digital specimens are developed to model the fatigue of the asphalt binder,mastic and mixture specimens based on the finite element method(FEM).Fatigue damage of asphalt concrete is simplified by a damage model.With proper selection of damage parameters,the simulation results agree well with laboratory test results and can be used as a basis for future fatigue research.
基金The authors would like to acknowledge the National Natural Science Foundation of China(Grant Nos.51978515,41941018)Shanghai Sailing Program(19YF1451400)Shanghai Municipal Science and Technology Major Project(2017SHZDZX02)for their financial support.
文摘The tensile behavior of hybrid fiber reinforced concrete(HFRC)is important to the design of HFRC and HFRC structure.This study used an artificial neural network(ANN)model to describe the tensile behavior of HFRC.This ANN model can describe well the tensile stress-strain curve of HFRC with the consideration of 23 features of HFRC.In the model,three methods to process output features(no-processed,mid-processed,and processed)are discussed and the mid-processed method is recommended to achieve a better reproduction of the experimental data.This means the strain should be normalized while the stress doesn’t need normalization.To prepare the database of the model,both many direct tensile test results and the relevant literature data are collected.Moreover,a traditional equation-based model is also established and compared with the ANN model.The results show that the ANN model has a better prediction than the equation-based model in terms of the tensile stress-strain curve,tensile strength,and strain corresponding to tensile strength of HFRC.Finally,the sensitivity analysis of the ANN model is also performed to analyze the contribution of each input feature to the tensile strength and strain corresponding to tensile strength.The mechanical properties of plain concrete make the main contribution to the tensile strength and strain corresponding to tensile strength,while steel fibers tend to make more contributions to these two items than PVA fibers.
文摘In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste （HCP） under a tensile force. A three-dimensional （3D） multiscale mechanical model is established using the combined Discrete Element Method （DEM）-Molecular Dynamics （MD） method in LAMMPS （Large-scale Atomic/ Molecular Massively Parallel Simulator）. In the 3D model, HCP consists of discrete particles and atoms. Simulation results show that the combined DEM-MD model is computationally efficient with good accuracy in predicting tensile failures of HCP.
基金supported by the open Fund of State Key Laboratory of Disaster Reduction in Civil Engineering(Grant No.SLDRCE15-03)Beijing major science and technology projects(Grant No.Z191100008019002).
文摘The thermal expansion mismatch between cement mortar and aggregate at high temperature is one of the main reasons causing the deterioration of concrete at high temperature.In this study,the thermal damage of concrete caused by the thermal expansion mismatch between aggregate and cement mortar was investigated using a meso-scale concrete model.The meso-scale concrete model is composed of mortar,aggregate and the interfacial transition zone(ITZ).Laboratory tests on the mechanical properties of cement mortar at high temperature were conducted to provide the necessary mechanical parameter for the meso-scale concrete model.The simulation results show that the particle size,content,distribution and mechanical properties of the aggregate have an effect on the thermal damage of concrete at high temperature.The smaller the particle size of concrete aggregate and the higher the elastic modulus of aggregate,the greater the damage of concrete under high temperature.Due to the increasing thermal expansion difference between aggregate and cement mortar,and the deterioration of the cement mortar with the increasing temperature,the damage of concrete increased sharply after 500℃.
